Isn't HR directly correlated to metabolic cost ? This is how all watches or apps do to measure the calories burnt during an activity. While the calculation is more or less accurate depending on the formula used and obviously the accuracy of your HR monitor this is your definite answer. Since your HR is higher in open shock case you can conclude that the metabolic cost is higher at the same energy output and climb time. If you think about it it makes sens really, before you can load your power meter, you first need to load your suspension to the point where it will sag to the point of support and then you will produce the power in the power meter. All the energy used in suspension preloading (bob) thus can't be measured by your powermeter at all.
Was your HR different between open and locked position in the same riding position, seated vs seated and standing vs standing and of so by how much? How did you distribute the different runs? It can have a big impacted on HR if it's measured at the end off a longer session vs at the start, especially in hot conditions and if 300 watts is about or above your threshold. Generally you will have a higher HR during standing efforts, both because the efficiency is lower and because you need a higher cardiac output and blood pressure to get the blood back to the heart from the legs.
Awesome video! Great to get your take since this is obviously more of an engineering question which I''l admit I have no background in, my degree is in exercise science. The upstream losses didn't occur to me when I was making the video but multiple people pointed it out in the comments. What this means is that when your suspension is open your power meter (for the purposes of training and pacing, not in actuality) is inaccurate. I've never heard anyone talk about this. This should be common knowledge for cross country mountain bikers at this point! That's my big takeaway from this whole experiment. Keep up the good work, love the channel.
First part of the question: Does the open suspension waste energy in terms of heat, answer no, because with a closed suspension the vertical force is then consumed by deformation of e.g. the tire deformation. All the first part explaining suspension friction etc was irrelevant. Second independent question: pedal efficiency with open suspension? Might be less efficient because you spend less time in your ideal bike fitted position.
1. We can agree that a moving suspension consumes energy (transfers energy into heat) This means: a) this energy is so small that you cannot measure it in comparison to your riding effort, or b) you go faster when you close it (which you dont) In this case, the energy must be transferred somewhere else into heat, e.g. stronger tyre deformation, stronger bending the frame etc otherwise you would go faster with a closed suspension. The 2nd unrelated question is complex, it may be harder to put out 300watt with an open suspension (less ideal riding position), your max power output might be lower. There are many other factors like surface, as you may save energy going smoother over obstacles, better traction etc etc...
You nailed where all the others fail on their analysis, by measuring output power alone and not energy consumed it is not possible to understand eficiency. Having said that, in an MTB, what matters is your efficency climbing on rough terrain (and not tarmac) where the wheel is stuck to the floor (opened) or jumping around (locked). The only way to measure that is to develop a series of sistematically reproducible experiments with different roughnes (from gravel to big stones/roots) and then see when if it is worth to climb with the switch opened or locked. To my knowledge nobody has done this publically and i believe it is not an easy one to do due to the complexity of a reproducible consistent setup.
The only off road climbs I have here that are long enough are very technical, and any times differences would be hidden by plain luck/technique on every rep. There are no fire roads, just steep rocky switchbacks. And in that case, I always leave the shock fully open for traction.
@@PeakTorque Standing is always going to have more metabolic cost than sitting since when standing you are using many more muscles to stabilize the position. While standing open vs locked out resulted in the same time, was there a difference in avg HR in standing open vs locked out? There might be a slight increase in HR in standing open if I’m reading that HR graph correctly. Would it be possible to get std dev and p value to see if significant?
Pulled out the thermo textbook, made some assumptions, and made a guess at how much thermal energy you loose to the shock. Over the hour at 300W you produce ~1080 kJ, and heating up the shock takes 16-20 kJ (worst case), so less than a 2% loss. There’s far more at play but some perspective is nice
@@profribasmat217 so do you prefer rim break or disc break, because the rim break is less wait? I am just joking, I too am also one for grammatical errors as simple as those. FYI, rim brakes babyyyyy!
TrailPOV has a whole series of videos analysing the characteristics of suspension designs with really nice diagrams. They go into things like anti-squat and all the words you might hear from bike companies that never get explained. Very fun and informative. czcams.com/channels/tThFO0v9rXvmM5nBc6CNrQ.html
Mate that was an excellent video, really well put together. I don't know where you're based but I work in the sport and exercise science department at Staffs uni and we have portable gas analysis equipment that could be used to address your point about metabolic cost independent of power output. Would love to run the experiment again in an ecologically valid environment (as you have here) and it would be even better if we got Dylan onboard. I feel a publication coming on.
As someone who has a very distant appreciation of engineering (I understand broad concepts mainly from motorsport videos etc), but have never gone deep into it or looked at the maths, you explain things so well to a relative layman and make it super interesting
Very interesting stuff. Having originally started watching the channel for the road bike design discussions, this video really highlighted something to me. There is some actual design engineering and science going into mountain bikes. By comparison, road bike engineering seem to just be [bad] design for manufacture and making some "sales engineer" claims about stiffness, very specific use case aero, weight etc. It's refreshing to see some science in bike design!
I agree. We spoke about this in the Kontra podcast. Check it out. There's not much going on in road bike design, and the value for money is so much worse.
Awesome video! Clear explanations of a lot of in depth topics and great conclusions to be made. Makes me wonder if a similar thing isn't occurring in road bikes with lower lateral stiffness. I think a video covering the effects of stiffness on drivetrain efficiency and metabolic efficiency could be great.
Spot on! When I saw Dylan Johnson video i knew right away, that it would be against law of physics, if the same amount of energy would be spent on rigid bike vs open suspension bike given same power and speed. There is no way that movement of parts in suspension system would be "for free". And he admits that during his tests he had higher average HR with open suspension, but he attributed that to the order of his test runs protocol: first locked, then open. But i knew that in HR differences lies the answer to that question. And measured power from power meter is only one in many variables in that equation, as it only measures what is happening between your foot and pedal, and does’t take into account the whole system. And BTW if it was true that open vs locked suspension doesn’t matter, the question of road bike stiffness also wouldn’t matter which, as we know, is not the case.
@Peak Torque The topic on "human energy-output COST" is a great one! It has "vaguely" been addressed I think, when bike fitters say things like "position needs to be aero as possible, while still maintaining highest possible power output within that position". Heart rate is a telling component, if we assume oxygen consumption is linked to pump cycles, and also, oxygen is the key component in "burning" calories, turning them into energy. There was a video on "veritasium" where he finds out, that we weigh about 300g less in the morning due to exhaling the "heavier" CO-2, which is the residue of our energy transformation system. I am completely going off topic, sorry. THANKS for geeking out on this high level, as you do !
Great research and results. I watched another similar programme a few months ago aith the same results. This makes choosing my next bike and fiddling with valves much less stressful.
You did a great job on breaking down anti squat and explaining the suspension work. One thing that both you and Dylan did not test, is the effect of locked and unlocked on actual off-road trails of various conditions where mountain bikes were designed to be used. What is the efficiency, power output, and metabolic expenditure on trails? Vibration, bumps, traction, and etc, one would think, would have an effect on the test results as well. Would be interesting to see the results off-road!
Great video, very well explained and we'll "exampled" discussion. I don't do any real engineering at my "engineering" job, so it's refreshing to go over this material, and even better that its regarding my favorite hobby.
Very good sound reasoning there, nice work! I, like you had a 'but wait a minute?" moment watching two other videos which appeared to demonstrate that there was no difference between the efficiency of active Vs locked out suspension. I had never really thought about how power meters work, and what they don't record, (because I can't afford one, and don't care enough). I do have a medium travel mountain bike with a rear lockout though, and I don't think I can be imagining how much easier smooth fire road climbs are with the suspension locked out are. These tests haven't spent much time discussing sprints either. I would have thought that would be an even more exaggerated example of power loss through suspension movement. As you were saying, the only way you can push against something and have most of that energy returned to you is by eliminating all damping. That is not a good thing for suspension control. There is plenty of discussion about lightweight wheels, with lower rotating mass and how they improve acceleration. I bet those gains are insignificant compared to the inertia of a system that loses energy through suspension compression.
First of all: Big Thanks for the information. Despite the fact, that there is a difference in effort to produce for example 300 W, the losses in the system are to small to be measured with the equipment used. So in terms of difference within the system there is none. Dylan showed it and you confirmed it. However: I still lock since it makes me feeling less effort, what brings us back to your conclusion.
And not only do you FEEL less effort it actually IS less effort locked out! The power meter only measures how much you're putting into crank to drive the back wheel. If you're putting in the same Watts into that wheel (aerodynamics held constant) the bike will go just as fast no matter what.. HAS to go just as fast. What the power meter DOESN'T MEASURE AT ALL is all the extra energy it takes to move your arms and legs to compensate for all the bouncing and also compressing dampeners in shocks to heat etc.. and all that doesn't contribute to the bike moving forward it's just extra wasted extra energy! The power meter is ENTIRELY the wrong tool to measure which is harder.. it's incapable of measuring that in this case!
As someone making an electronic system to control lockout for my final year project this video was an awesome roller coaster of emotions haha! Awesome video as always
Nice experimental design, and clear results. An interesting analysis, if you have the data would be to look at the efficiency factor, as defined by Friel (NP/avg HR), using that as the response variable might yield a different result than using time.
Another great vid to talk and laugh about during the summer afternoons we might spend over meze in that Greek island...each 10 time zones away from it, in different directions. Btw, I flip the shock switch climbing long stretches, but it is not the end of the world if you don't. I don't bother with the fork.
As exhaust gas analysis is difficult, expensive, and not feasible while riding, doing a TT at FTP is a good way to keep a consistent effort. Power output measured at the power meter (along with speed) will be lower for the less efficient setup.
Your next venture seems clear. The metabolic costs of the suspension setting and body position must be explored! It seems like one of those large, inclinable treadmills and the necessary biometric equipment should do the trick!
Excellent test! I'm just as surprised as you are about the results. Thinking about it, I think your statement regarding the metabolic cost being the reason for the sensation of 'inefficiency' in the open position is spot on. If you think about it, the power meter strain gauge is more stable in the locked position, and thus, more accurate. In the open position, you reach a certain threshold where some of that power is lost in moving the suspension. In that instant, the position of the power meter is moving with your foot (which would reduce the strain gauge reading, and thus your displayed power), and in order to compensate for this movement, you must've been pushing more than 300w in order to average 300w. I'm not an engineer, but that explanation makes intuitive sense to me, but it might be completely off.
I watch every video both you and Dylan put out and really appreciate both of you. I have a 2018 Specialized Epic (100mm front/rear) with the Brain (rear only) and had been riding with the Brain in the second stiffest setting for 3 years. I thought it was very efficient and every time I rode it, was very impressed on how well it worked. However, after watching Dylan's original video on the topic, I decided to do a ride with it wide open (basically with the Brain off) and was surprised by the results. I have been a little faster but, more importantly, considerably more comfortable over the course of a 3-4 ride. I finish the rides less fatigued but no more physically tired than I did with the Brain engaged. My caloric burns, based on heart rate, not power, are basically identical to the same rides with the Brain engaged. So if having the suspension fully open is more metabolically taxing, I certainly don't notice it. Conditions play a big role here I believe because my local trails are very technical with nothing but roots and rocks 90% of the time. Perhaps all of this matters more on tarmac, but on even slightly technical trails, I won't be damping my compression in any way again. Thanks to both you and Dylan for such great content.
This is because you were climbing singletrack and rough terrain I presume, where more active suspension is likely to be less physically taxing for the same average speed.
Thank you for giving a clear explanation of why lockouts help. I’ve seen some videos basically saying they don’t matter, but by using a power meter as a control and your heart rate and effort as the variable, you haven’t proven the value of lockouts. Now I don’t feel like I wasted my money!🤣
Thanks for posting this, I really liked the explanation about anti-squat. Is there any chance you could extend this and tell us how the Yeti Switch Infinity system works? It's been bugging me for years!
Great video and conclusion on metabolic cost. The problem to me though is if you’re climbing on technical terrain vs. flat road then having a locked out shock will likely hinder your climbing ability and probably increase the metabolic load of the bike bouncing up and down and demanding more control and stability from the rider. Also. What about the impact of bike geometry on anti squat? I wound have thought the seat tube angle plays a role here and maybe Canyon Strive adjusting the angles on the go provided better climbing anti squat then simply altering the shock compression which the Strive doesn’t do.
This is exactly right. You would not lock out your suspension on a steep and/or technical climb. Your rear wheel would be bouncing and losing traction causing an increase in total effort. On a paved road, of course it makes sense to lock out your suspension
Great video ! Surprising results. Heart rate would be a better indicator of efficiency,as you saw with the standing efforts. This is what we feel,the energy expense with the bobbing,sag & other losses,we expect the times to be slower. My full sus,has been a frame set only for a long time. So I only have my Kona Kahuna 29er hardtail to go by,usually just locked out on the road or any smooth section. How much does tyre pressure affect the result ? I use 15-30psi.
Hey @Peak Torque, with all the fuzz trying to save a few watts in cycling, it got me wondering how much more distance is covered when standing up vs sitting? See Contador for example, he greatly exagerates when pedalling out of the saddle, going from side to side and doing an "S shape" on the ground... even if that is 2-3%, that's already a lot of time "saved" if just going in a straight line... just an idea for a future video 👍
The data is right there, but it would nice to see this run, even just a single for each one, with your heart rate as close to normalized as possible. The metabolic efficiency isn't particularly important for this, so long as the relative effect of each setting is greater than error.
I like to discuss a crude way to guesstimate the power cost of the moving damper. First, we can safely assume the damping energy loss is less than the peak stored energy in the spring and use the peak spring stored energy as the upper bound estimation. Let’s start with an ideal coil spring without a damper and assume a 75kg rider sag @ 30mm of travel. The stored energy is W_sag = 0.5 kx^2 = 0.5 (Weight/x_sag) x_sag^2 = 11J. To simplify the math, I assume the deepest travel of the pedaling bob is twice the sag, thus the peak stored energy per pedal stroke is 4 W_sag and the change is about 33J per pedal stroke. Further assuming you were pedaling at 60rpm, there are two pedal strokes per second and 66W of power is cycling through the spring when there is no damper. If we use your heart rate near the end of effort to proxy your metabolic cost using a crude linear P_output - HR relationship. 300W @ 158bpm implies additional 13W @ 165bpm. Overall, I would guess about 20% of the spring stored energy is lost to the damper with all the assumptions here.
Thanks for the insta360 recommendation, I went with a oneR with 1-inch lens, 2hr battery, and wireless mic. I can't wait to start filming with it, need to do the firmware update first... and get a groupset...
Great video - wouldn’t a better test be a max effort climb vs a constant watts. If a closed shock is more efficient- your time to the top of the hill should be quicker. Thoughts?
Yeah but humans vary too much. At best you would be testing the placebo effect, since there’s no way to test such that he can’t tell if the suspension is locked out or not
Great video, thank you very much for the explanation. Recently, I have watched a few videos about this subject. They all had the same conclusion and the same experiment set up. Basically, the issue is that an experimental setup is incorrect. I wonder whether we can think about this problem as if there would be a spring between shoes and pedals. In order to put 300 w to the crankset, a rider would have to compress the spring first which would require an additional effort.
Very interesting video and I love the MTB content! Pinkbike often does a climbing comparison when testing different dual suspension bikes and come out with significantly different times at the same output power. Does this make any sense?
I've seen some of those. And some work done by Seb Stott had different times at isopower too (very similar climb length to Dylan and myself) but his results i think were inconclusive as the times differed by under 1 percent iirc.
@@PeakTorque this is the video I was talking about, they got quite a variation on the same climb with different bikes at the same average power: czcams.com/video/Nl0fXOp4oTM/video.html
My friend pointed out Dylan’s assumption that the power meter measurement is equivalent to your actual power consumed, and I was hoping someone on here would address it. Thanks for setting the record straight! It would be very interesting to see the results of a lab metabolic efficiency measurements across different suspension designs
Good test. Next steps: You could buy, hire or get sponsored for a portable metabolic gas analyser! Or build a bicycle dyno with a static analyser as your next project! To get a full answer (because we ride at different intensities) you would also have to include a test with different levels of HR because HR is not linear with O2 consumption. So do tests below first lactate threshold turn point, then tests at lactate threshold, then one above (full anaerobic). So overall, with the HR data, could you conclude here that the metabolic cost will be pretty small? If large surely this would show in increased HR? Many thanks. Great work you're doing. DazO
@3:15 The heat added to the air spring as it's compressed isn't lost, the air decompresses almost instantly. Heat in the air can comes from the air can surrounding the damper.
Would be interesting to see what the difference is like on an off road climb, as locked out you're going to have a harsh ride and less traction, whereas open damping will use more energy but more efficiently.....
Great video. When Standing on a road bike you can put more weight on the handle bars more easily. Comparing HR when standing Road to MTB isn't just about the shock. What was the HR difference seated between locked and open? Thanks.
Wow. I was expecting to get lost again …. But this time I understood everything! Well explained. After watching Dylan’s video a while ago I was thinking “why didn’t he just put heart rate against the times?” But I guess presenting the heart rate data against the run times would show quite a low difference probably …. and it would be subject to build up of fatigue during testing. I have never thought before about the power meter reading Vs physical effort cost ….. Having had power meters for a while I guess I kind of linked physical effort with watts …. On any one bike, especially a road bike with fixed geometry and similar road surfaces all the time, then this could be true …. But actually now I understand that this is not the case, especially for MTB where position, geometry and rolling surface changes all the time!
RE; expired gas analysis: you'd need volume as well as oxygen/CO2 inspiation/expiration. One CO2 molecule generated by respiration of glucose does not release the same amount of energy as respiration of a ketone body etc. Even if you assume a "respiratory quotient" you'd still need tidal volumes too. You can already measore CO2 concentrarion quite easily: used in hospitals for 'conscious sedation' sometimes already.
Another great video, thanks to both Dylan and Peak for continuing to surface up evidence based research that validates the bike industry's assumptions and associated marketing.
Wasn't DJ's HR 4-5 beats higher on his run that didn't have his shock locked out? Either way, good job on the video and it points out that properly devised testing is just as important as doing the testing itself.
Here's a test suggestion: Build an insulated calorimeter ("foam box") around the shock to measure temperature gain of the mass of materials inside the box in order to measure the energy loss. Compare energy loss from open vs lock-out mode. Then publish a white paper. Thanks in advance😊
For me I'll lock out the rear shock on climbs that are not as bumpy and typically I feel way better and less exhausted as opposed to when I'm not locked out. So yeah, this video explains the reason why~
@Peak Torque In the case of diving deeper into the metabolic cost when climbing in a standing position ... What would you think about adding strain gauges to the handlbars? Shouldn't this allow for calculating pulling and pushing forces on the bars, which could then be related to the heart rate? They could then give us some more insight on metabolic efficiency, couldn't it?
Related to your "power meter only measures output power" comment. To take that statement one step further, the power meter only measures your output power at the crank, not the true output power of your legs. An obvious demonstration of this is if you stand on the bike and hop in place without pedaling. A power meter will read zero, but your legs are clearly putting out (significant) power to lift of your center of mass. This energy is dissipated in your muscles and suspension when your center of mass falls. I think this happens when pedaling too, particularly when standing and pedaling it's hard to keep your COM a constant height, and some of this COM-bob energy gets burned in the suspension rather than being recovered during the pedal stroke. Even sitting and pedaling, if the suspension is cycling, that means your COM must be moving up and down, and some of the energy you put into raising your COM gets dissipated by the suspension every cycle. Another example where the power meter and human effort can be dramatically different - if both feet are loaded downwards on both the up and downstroke (like in the pedaling standing example, if you don't fully unweight or pull upwards on your back foot), the leg on the upstroke is doing negative work while the leg on the downstroke is doing positive work. These numbers are extreme, but say the leg on the downstroke is doing 400 watts and the leg on the upstroke is doing -100, the metabolic cost would be much higher than +300/-0 (~1/3 higher if we assume muscle efficiency is constant, we can't regen negative work sadly) , but the power meter would measure 300W for both. I don't think people pedal like this, just illustrating the power meter point.
What you'd need to do is measure the non-tangential forces. I'd imaging that with the suspension open the pedaling action is more likely to produce higher non-tangential forces at higher metabolic cost. That's why, typically, climbing out of the saddle is less efficient - at the bottom of the stroke you're more inclined to push straight down because of body weight, rather than have your body weight supported by the saddle.
After watching GPLama's video on the Dura-Ace power meter test, do you think the discrepancy was down to the bike being in the trainer? I saw your comment about pivoting. Also, do you think the material differences between Ultegra and Dura Ace will make a difference? Still considering the Shimano PM cranks, but I'd like to see more testing and reviews. Thank you!
It would be very interesting to do the same test (standing is useless for mtb) but with 3 different bikes with different levels of AS, measuring time and HR, with powermeter constant. High AS bikes are always thought as efficient pedaing bikes that don't need the lockout but the force transmitted from the chain to extend the rear suspension has to add to the total energy used. Also considering that high AS bikes use their chain to fight off bob when the shock is open, you may see differences between open and locked while using your powermeter.
@Peak Torque this is a very valid suggestion about analysing results for different pivot kinematics, I'd love to see this test. Also when i watched both your video and Dylans Video, I cant help but think that there is a flaw in everyone in the cycling world thinking iso-power is a the "best" control method. I understand that a comfortable sub threshold power makes it repeatable and reduces fatigue for the repeat runs. but as you find, put same power out you get the same times. In my opinion Power is a more suited to measure difference, and not be the control. To me this question is about rider efficiency, and as you point out thats metabolic efficiency then riding at HR threshold or consistent HR may be more relevant? Or maybe even ignore the climb factor and just have a set 5-10 minute gravel road or tarmac loop and do all out TT?
There have been lots of tests in the past proving that open suspension does not lead to power loss. It seems the industry forgot for a while, and then all these XC bikes started coming with lockouts again. The suspension movement does dictate the rhythm of the pedaling. If it's counter to how you would like to be pedaling, increasing compression damping or fully locking it out can be beneficial, not for efficiency, but for the ability to hit the highest power numbers. This is most often felt in a smooth pavement sprint to the finish.
nice testing, thanks. How about a bike with front suspension only? I have a Canyon Pahtlite 6 and it has a 75mm front suspension fork. I use it for road and light paths, but mostly road (of variable quality). Should I lock the front suspension when on tarmac? I like to keep it open but my brother tells me I should lock it when on tarmac. However, there is the video of Dylan Johnson you mentioning, indicating there are studies where locking/unlocking your front fork makes no difference in your performance at all. I mean FRONT fork only of course, no rear suspension or anything like that
Love this type of detail and very much appreciate the time investment to pull this off but, the bigger use case that racers are looking for a major advantage is the full gas sprint for race starts and full gas sprint finishes where the watts are much higher and the new technology in shocks and forks might not filter out like the lower watt stuff of a seated or standing climb. When you are trying to get a great single track drop in position from a mass start with a long open start sprint would you see an advantage with a rear shock lockout?
It would be interesting to compare ftp test results on both locked and unlocked suspensions. The difference between the two would give an idea of the decrease in metabolic (upstream) efficiency.
@@stevemurray710 When doing an ftp test you are limited by your metabolic threshold, which can be considered as the "energy input" into this system. Applied to the unlocked suspension bike, this same threshold limitation will result in a lower power outpout at the powermeter because the lesser efficiency of that system, as opposed to the locked suspension. How much of an effiency decrease is the big question.
One way to think about this is if you replaced a the cranks with a 300W motor, the bike would go the same speed no matter how much you bounced up and down on the suspension. The energy you waste bouncing the suspension is separate from the 300W going into the chain. Was there any difference in heart rate between locked and open runs? That might give some insight into the higher metabolic cost.
I could tell that it had something to do with how power is measured between the cranks and rear wheel but I was still surprised because I thought that all this motion in the frame would impede the bike movement somehow. Like a spring that oscillated back and forth while moving in a direction parallel to the oscillation, I thought maybe it would add rolling resistance or something. I figured that in one half of the oscillation the back wheel would be "pushed" back thus impeding its movement. Then again I guess the other half would pull the back wheel forward canceling out the effect?
Fun & interesting experiment, would be very interested in being able to truly quantify the open v locked question, personally I tune my suspension to work for me (at least I think that) on climbs. On dirt say a 50km ride with 2000m climbing, I feel less drained and put in faster times with my suspension open the whole time, if it’s locked out for climbs I find myself very fatigued from the harsh stiff ride, and can get caught out by a technical feature, in the end do I actually burn more fuel open or closed 🧐🤔 🤷♂️
Thanks for the video. I have two (probably dumb) questions. 1- Many mountain bike climbs are 15% to 30%, would the outcome be the same,? 2- According to your test results, would this mean that road bike rigidity is overrated?
well in order to compare road and mountain bike in climbing efficiency they should be the same weight. There are also stuff like tyre width and body position, which influences bike efficiency on tarmac climbs.
I think you could make a reasonable approximation of metabolic cost by measuring expiratory volume (spirometry) or respiratory rate (heart rate monitor).
Sooooo we need hub based power meters on mountain bikes to compensate for the suspension losses and get accurate power output readings? Like crank vs wheel HP in cars?
Smart! Same power into that chain/crank HAS to result in same speed (aerodynamics held constant)… basically comes down to wrong test! Test used is incapable of getting the answer we want!
Can't heart rate be the a rough measurable metric to decide how efficient each suspension setup is? In theory if some activity is harder for your body, your heartrate goes up, if you maintain said load. You can also base your load on certain heartrate.
Road bike idustry - proud to present next year model rigid frameset, that get 4.7% stiffer MTB idustry - there is no time loss between locked and unlocked suspension
If the maximum amount of human power output is fixed and is assumed to occur at maximum heart rate, then you should be able to see power lost as velocity delta of the bike over the distance traveled during a maximum sprint (Power = Force x Velocity). Measure bike acceleration with an accelerometer at maximum heart rate and integrate to calculate max velocity along with directly measuing bike velocity and you'll have your answer. Conduct the test over a few days alternating which variable is tested first.
I´m not a scientist nor engineer but when I think about it. Does it matter if it is locked or not when power is measured on the bike (spindle, pedals or cranks)? Power applied is going to be transfered via chain on the rear wheel anyway. If you could measure power from legs (hip- knee-ankle linkage) and testing terrain is very rough so suspension is actively changing biomechanics of your stroke then this would be the place where power loss/gain could be found. Just an idea.
It could have been interesting if have added your heart rate numbers to the power spreadsheet. It could show some of the differences. The conclusion must be that powermeters doesn’t work for mountainbikes, your have to use a heartrate monitor.
Try a test of peddling up a bumpy gravel road or single track. I’d wager the metabolic cost is less with the suspension open because the suspension is absorbing the trail chatter instead of your body.
Did you do all this on-road? I'm surprised locked-out didn't give you a bit of an advantage there, but watching the seated shock movement you can see anti-squat is essentially dealing with it fine. I think if you repeated this over more rugged terrain you'd see an advantage to climbing "open", because you don't lose as much energy getting the bike over terrain features.
Did you do a HR comparison of seated effort open vs closed? I'm not surprised standing felt inefficient, you're fighting both the shock and the fork then.
Is it generally true, then, to say that the same wattage will always be metabolically more taxing (calories/watt) when standing vs sitting, even on rigid frames like road bikes?
What if you're not adapted to climb suspension open so your metabolic efficiency was lower? Maybe it's more efficient for a rider who always rides unlocked?
1/2 way through I was wondering about how your HR was behaving in the different tests. As well as wondering when the baggy vs lycra police would start a debate in the comments...
For those who commented about HR, it is discussed at 16:11. HR is slightly higher for the open efforts, and much higher for the standing efforts.
Isn't HR directly correlated to metabolic cost ? This is how all watches or apps do to measure the calories burnt during an activity. While the calculation is more or less accurate depending on the formula used and obviously the accuracy of your HR monitor this is your definite answer. Since your HR is higher in open shock case you can conclude that the metabolic cost is higher at the same energy output and climb time. If you think about it it makes sens really, before you can load your power meter, you first need to load your suspension to the point where it will sag to the point of support and then you will produce the power in the power meter. All the energy used in suspension preloading (bob) thus can't be measured by your powermeter at all.
@@eg4760 yep that's the conclusion of the video
Was your HR different between open and locked position in the same riding position, seated vs seated and standing vs standing and of so by how much?
How did you distribute the different runs? It can have a big impacted on HR if it's measured at the end off a longer session vs at the start, especially in hot conditions and if 300 watts is about or above your threshold.
Generally you will have a higher HR during standing efforts, both because the efficiency is lower and because you need a higher cardiac output and blood pressure to get the blood back to the heart from the legs.
Wow. You actually took a logical and well thought out approach to investigating something for once. Congrats my dude. You are improving yourself.
This was definitely a good data point to include to push your point home
Awesome video! Great to get your take since this is obviously more of an engineering question which I''l admit I have no background in, my degree is in exercise science. The upstream losses didn't occur to me when I was making the video but multiple people pointed it out in the comments. What this means is that when your suspension is open your power meter (for the purposes of training and pacing, not in actuality) is inaccurate. I've never heard anyone talk about this. This should be common knowledge for cross country mountain bikers at this point! That's my big takeaway from this whole experiment. Keep up the good work, love the channel.
First part of the question: Does the open suspension waste energy in terms of heat, answer no, because with a closed suspension the vertical force is then consumed by deformation of e.g. the tire deformation.
All the first part explaining suspension friction etc was irrelevant.
Second independent question: pedal efficiency with open suspension? Might be less efficient because you spend less time in your ideal bike fitted position.
I was expecting Backhat Dylan to comment 👍
@@romanmathaes8451 no the tyre is different to the suspension unit because the damping is different, you cannot assimilate the two systems.
Do you have HR data from your tests? It's lower tech, but that may be the better metric for testing.
1. We can agree that a moving suspension consumes energy (transfers energy into heat)
This means: a) this energy is so small that you cannot measure it in comparison to your riding effort, or b) you go faster when you close it (which you dont)
In this case, the energy must be transferred somewhere else into heat, e.g. stronger tyre deformation, stronger bending the frame etc otherwise you would go faster with a closed suspension.
The 2nd unrelated question is complex, it may be harder to put out 300watt with an open suspension (less ideal riding position), your max power output might be lower.
There are many other factors like surface, as you may save energy going smoother over obstacles, better traction etc etc...
You nailed where all the others fail on their analysis, by measuring output power alone and not energy consumed it is not possible to understand eficiency. Having said that, in an MTB, what matters is your efficency climbing on rough terrain (and not tarmac) where the wheel is stuck to the floor (opened) or jumping around (locked). The only way to measure that is to develop a series of sistematically reproducible experiments with different roughnes (from gravel to big stones/roots) and then see when if it is worth to climb with the switch opened or locked. To my knowledge nobody has done this publically and i believe it is not an easy one to do due to the complexity of a reproducible consistent setup.
The only off road climbs I have here that are long enough are very technical, and any times differences would be hidden by plain luck/technique on every rep. There are no fire roads, just steep rocky switchbacks. And in that case, I always leave the shock fully open for traction.
@@PeakTorque Standing is always going to have more metabolic cost than sitting since when standing you are using many more muscles to stabilize the position. While standing open vs locked out resulted in the same time, was there a difference in avg HR in standing open vs locked out? There might be a slight increase in HR in standing open if I’m reading that HR graph correctly. Would it be possible to get std dev and p value to see if significant?
I had never thought about the 'upstream' energy before you even look at the cranks, that's a new perspective for me.
The big part of the puzzle that no one really looks at.
Pulled out the thermo textbook, made some assumptions, and made a guess at how much thermal energy you loose to the shock. Over the hour at 300W you produce ~1080 kJ, and heating up the shock takes 16-20 kJ (worst case), so less than a 2% loss. There’s far more at play but some perspective is nice
Anyone who doesn’t know what loose and lose mean, can’t do physics.
@@profribasmat217 so do you prefer rim break or disc break, because the rim break is less wait?
I am just joking, I too am also one for grammatical errors as simple as those. FYI, rim brakes babyyyyy!
@@profribasmat217 try harder, kid
what about saved energy due to not carrying the lockout cables, levers etc...
The best explanation of anti-squat I have ever heard. Great video!
Great to hear!
TrailPOV has a whole series of videos analysing the characteristics of suspension designs with really nice diagrams. They go into things like anti-squat and all the words you might hear from bike companies that never get explained. Very fun and informative. czcams.com/channels/tThFO0v9rXvmM5nBc6CNrQ.html
Mate that was an excellent video, really well put together. I don't know where you're based but I work in the sport and exercise science department at Staffs uni and we have portable gas analysis equipment that could be used to address your point about metabolic cost independent of power output. Would love to run the experiment again in an ecologically valid environment (as you have here) and it would be even better if we got Dylan onboard. I feel a publication coming on.
As someone who has a very distant appreciation of engineering (I understand broad concepts mainly from motorsport videos etc), but have never gone deep into it or looked at the maths, you explain things so well to a relative layman and make it super interesting
Very interesting stuff. Having originally started watching the channel for the road bike design discussions, this video really highlighted something to me. There is some actual design engineering and science going into mountain bikes. By comparison, road bike engineering seem to just be [bad] design for manufacture and making some "sales engineer" claims about stiffness, very specific use case aero, weight etc. It's refreshing to see some science in bike design!
100%! Even looking at components, there's so much more complexity seen in similarly priced groupsets such as Deore in comparison to 105!
I agree. We spoke about this in the Kontra podcast. Check it out. There's not much going on in road bike design, and the value for money is so much worse.
Awesome video! Clear explanations of a lot of in depth topics and great conclusions to be made. Makes me wonder if a similar thing isn't occurring in road bikes with lower lateral stiffness. I think a video covering the effects of stiffness on drivetrain efficiency and metabolic efficiency could be great.
Spot on! When I saw Dylan Johnson video i knew right away, that it would be against law of physics, if the same amount of energy would be spent on rigid bike vs open suspension bike given same power and speed. There is no way that movement of parts in suspension system would be "for free". And he admits that during his tests he had higher average HR with open suspension, but he attributed that to the order of his test runs protocol: first locked, then open. But i knew that in HR differences lies the answer to that question. And measured power from power meter is only one in many variables in that equation, as it only measures what is happening between your foot and pedal, and does’t take into account the whole system. And BTW if it was true that open vs locked suspension doesn’t matter, the question of road bike stiffness also wouldn’t matter which, as we know, is not the case.
@Peak Torque
The topic on "human energy-output COST" is a great one!
It has "vaguely" been addressed I think, when bike fitters say things like "position needs to be aero as possible, while still maintaining highest possible power output within that position".
Heart rate is a telling component, if we assume oxygen consumption is linked to pump cycles, and also, oxygen is the key component in "burning" calories, turning them into energy.
There was a video on "veritasium" where he finds out, that we weigh about 300g less in the morning due to exhaling the "heavier" CO-2, which is the residue of our energy transformation system.
I am completely going off topic, sorry.
THANKS for geeking out on this high level, as you do !
Great research and results. I watched another similar programme a few months ago aith the same results. This makes choosing my next bike and fiddling with valves much less stressful.
Never seen any tests so detailed on any other bike channels… huge thumbs up
Terrific stuff, man. The answer seems obvious in retrospect, but only because you explained it so well.
Thanks!
You did a great job on breaking down anti squat and explaining the suspension work. One thing that both you and Dylan did not test, is the effect of locked and unlocked on actual off-road trails of various conditions where mountain bikes were designed to be used. What is the efficiency, power output, and metabolic expenditure on trails? Vibration, bumps, traction, and etc, one would think, would have an effect on the test results as well.
Would be interesting to see the results off-road!
This has been a very interesting watch, thank you
Great video, very well explained and we'll "exampled" discussion. I don't do any real engineering at my "engineering" job, so it's refreshing to go over this material, and even better that its regarding my favorite hobby.
Very good sound reasoning there, nice work!
I, like you had a 'but wait a minute?" moment watching two other videos which appeared to demonstrate that there was no difference between the efficiency of active Vs locked out suspension. I had never really thought about how power meters work, and what they don't record, (because I can't afford one, and don't care enough). I do have a medium travel mountain bike with a rear lockout though, and I don't think I can be imagining how much easier smooth fire road climbs are with the suspension locked out are.
These tests haven't spent much time discussing sprints either. I would have thought that would be an even more exaggerated example of power loss through suspension movement. As you were saying, the only way you can push against something and have most of that energy returned to you is by eliminating all damping. That is not a good thing for suspension control. There is plenty of discussion about lightweight wheels, with lower rotating mass and how they improve acceleration. I bet those gains are insignificant compared to the inertia of a system that loses energy through suspension compression.
First of all: Big Thanks for the information. Despite the fact, that there is a difference in effort to produce for example 300 W, the losses in the system are to small to be measured with the equipment used. So in terms of difference within the system there is none. Dylan showed it and you confirmed it. However: I still lock since it makes me feeling less effort, what brings us back to your conclusion.
And not only do you FEEL less effort it actually IS less effort locked out! The power meter only measures how much you're putting into crank to drive the back wheel. If you're putting in the same Watts into that wheel (aerodynamics held constant) the bike will go just as fast no matter what.. HAS to go just as fast. What the power meter DOESN'T MEASURE AT ALL is all the extra energy it takes to move your arms and legs to compensate for all the bouncing and also compressing dampeners in shocks to heat etc.. and all that doesn't contribute to the bike moving forward it's just extra wasted extra energy!
The power meter is ENTIRELY the wrong tool to measure which is harder.. it's incapable of measuring that in this case!
If it was harder it would have been be slower, but it wasn’t.
As someone making an electronic system to control lockout for my final year project this video was an awesome roller coaster of emotions haha! Awesome video as always
Arduino, altimeter, buzzer. Buzz at the top. Job done.
Nice experimental design, and clear results. An interesting analysis, if you have the data would be to look at the efficiency factor, as defined by Friel (NP/avg HR), using that as the response variable might yield a different result than using time.
Another great vid to talk and laugh about during the summer afternoons we might spend over meze in that Greek island...each 10 time zones away from it, in different directions. Btw, I flip the shock switch climbing long stretches, but it is not the end of the world if you don't. I don't bother with the fork.
As exhaust gas analysis is difficult, expensive, and not feasible while riding, doing a TT at FTP is a good way to keep a consistent effort. Power output measured at the power meter (along with speed) will be lower for the less efficient setup.
Your next venture seems clear. The metabolic costs of the suspension setting and body position must be explored! It seems like one of those large, inclinable treadmills and the necessary biometric equipment should do the trick!
Excellent test! I'm just as surprised as you are about the results. Thinking about it, I think your statement regarding the metabolic cost being the reason for the sensation of 'inefficiency' in the open position is spot on. If you think about it, the power meter strain gauge is more stable in the locked position, and thus, more accurate. In the open position, you reach a certain threshold where some of that power is lost in moving the suspension. In that instant, the position of the power meter is moving with your foot (which would reduce the strain gauge reading, and thus your displayed power), and in order to compensate for this movement, you must've been pushing more than 300w in order to average 300w.
I'm not an engineer, but that explanation makes intuitive sense to me, but it might be completely off.
Great bit of analysis.
I watch every video both you and Dylan put out and really appreciate both of you. I have a 2018 Specialized Epic (100mm front/rear) with the Brain (rear only) and had been riding with the Brain in the second stiffest setting for 3 years. I thought it was very efficient and every time I rode it, was very impressed on how well it worked. However, after watching Dylan's original video on the topic, I decided to do a ride with it wide open (basically with the Brain off) and was surprised by the results. I have been a little faster but, more importantly, considerably more comfortable over the course of a 3-4 ride. I finish the rides less fatigued but no more physically tired than I did with the Brain engaged. My caloric burns, based on heart rate, not power, are basically identical to the same rides with the Brain engaged. So if having the suspension fully open is more metabolically taxing, I certainly don't notice it. Conditions play a big role here I believe because my local trails are very technical with nothing but roots and rocks 90% of the time. Perhaps all of this matters more on tarmac, but on even slightly technical trails, I won't be damping my compression in any way again. Thanks to both you and Dylan for such great content.
This is because you were climbing singletrack and rough terrain I presume, where more active suspension is likely to be less physically taxing for the same average speed.
@@SunsPSD1 You are correct. And that makes sense.
Thank you for giving a clear explanation of why lockouts help. I’ve seen some videos basically saying they don’t matter, but by using a power meter as a control and your heart rate and effort as the variable, you haven’t proven the value of lockouts. Now I don’t feel like I wasted my money!🤣
Great video and great point!
Great analysis. Your car engine analogy makes perfect sense. In my mind I'm an efficient GR Yaris engine, but reality is more BMC A series.
Haha, low capacity AND low power 😀
Thanks for posting this, I really liked the explanation about anti-squat. Is there any chance you could extend this and tell us how the Yeti Switch Infinity system works? It's been bugging me for years!
Love to see a youtuber build off of another's video and nice job crediting Dylan!
Great video and conclusion on metabolic cost. The problem to me though is if you’re climbing on technical terrain vs. flat road then having a locked out shock will likely hinder your climbing ability and probably increase the metabolic load of the bike bouncing up and down and demanding more control and stability from the rider.
Also. What about the impact of bike geometry on anti squat? I wound have thought the seat tube angle plays a role here and maybe Canyon Strive adjusting the angles on the go provided better climbing anti squat then simply altering the shock compression which the Strive doesn’t do.
This is exactly right. You would not lock out your suspension on a steep and/or technical climb. Your rear wheel would be bouncing and losing traction causing an increase in total effort. On a paved road, of course it makes sense to lock out your suspension
@@tmunk123 correct
Thanks for that, that makes complete sense. But i needed you to tell me before i could realise that.
Excellent video dismissing an old chestnut! Thank you!
Great content as always. My most pressing question is what was that Le col jersey you were wearing? I’ve never seen it
Very thorough analysis, PT. Would a variance/change in cadence between the different testing scenarios affect the outcome ?
Great video ! Surprising results. Heart rate would be a better indicator of efficiency,as you saw with the standing efforts. This is what we feel,the energy expense with the bobbing,sag & other losses,we expect the times to be slower. My full sus,has been a frame set only for a long time. So I only have my Kona Kahuna 29er hardtail to go by,usually just locked out on the road or any smooth section. How much does tyre pressure affect the result ? I use 15-30psi.
Hey @Peak Torque, with all the fuzz trying to save a few watts in cycling, it got me wondering how much more distance is covered when standing up vs sitting? See Contador for example, he greatly exagerates when pedalling out of the saddle, going from side to side and doing an "S shape" on the ground... even if that is 2-3%, that's already a lot of time "saved" if just going in a straight line... just an idea for a future video 👍
The data is right there, but it would nice to see this run, even just a single for each one, with your heart rate as close to normalized as possible. The metabolic efficiency isn't particularly important for this, so long as the relative effect of each setting is greater than error.
I like to discuss a crude way to guesstimate the power cost of the moving damper. First, we can safely assume the damping energy loss is less than the peak stored energy in the spring and use the peak spring stored energy as the upper bound estimation. Let’s start with an ideal coil spring without a damper and assume a 75kg rider sag @ 30mm of travel. The stored energy is W_sag = 0.5 kx^2 = 0.5 (Weight/x_sag) x_sag^2 = 11J. To simplify the math, I assume the deepest travel of the pedaling bob is twice the sag, thus the peak stored energy per pedal stroke is 4 W_sag and the change is about 33J per pedal stroke. Further assuming you were pedaling at 60rpm, there are two pedal strokes per second and 66W of power is cycling through the spring when there is no damper. If we use your heart rate near the end of effort to proxy your metabolic cost using a crude linear P_output - HR relationship. 300W @ 158bpm implies additional 13W @ 165bpm. Overall, I would guess about 20% of the spring stored energy is lost to the damper with all the assumptions here.
Good estimations. It could be possible to measure some of that 13W heat output by measuring the temperature of the damper itself.
Thanks for the insta360 recommendation, I went with a oneR with 1-inch lens, 2hr battery, and wireless mic. I can't wait to start filming with it, need to do the firmware update first... and get a groupset...
Great video - wouldn’t a better test be a max effort climb vs a constant watts. If a closed shock is more efficient- your time to the top of the hill should be quicker. Thoughts?
Yeah but humans vary too much. At best you would be testing the placebo effect, since there’s no way to test such that he can’t tell if the suspension is locked out or not
Yes! Scientific sense prevails! Perfect video!
Great video, thank you very much for the explanation. Recently, I have watched a few videos about this subject. They all had the same conclusion and the same experiment set up. Basically, the issue is that an experimental setup is incorrect. I wonder whether we can think about this problem as if there would be a spring between shoes and pedals. In order to put 300 w to the crankset, a rider would have to compress the spring first which would require an additional effort.
Very interesting video and I love the MTB content! Pinkbike often does a climbing comparison when testing different dual suspension bikes and come out with significantly different times at the same output power. Does this make any sense?
I've seen some of those. And some work done by Seb Stott had different times at isopower too (very similar climb length to Dylan and myself) but his results i think were inconclusive as the times differed by under 1 percent iirc.
@@PeakTorque this is the video I was talking about, they got quite a variation on the same climb with different bikes at the same average power: czcams.com/video/Nl0fXOp4oTM/video.html
My friend pointed out Dylan’s assumption that the power meter measurement is equivalent to your actual power consumed, and I was hoping someone on here would address it. Thanks for setting the record straight! It would be very interesting to see the results of a lab metabolic efficiency measurements across different suspension designs
He did not make that assumption. He specifically said that he saw some hr differences.
Good test. Next steps: You could buy, hire or get sponsored for a portable metabolic gas analyser! Or build a bicycle dyno with a static analyser as your next project! To get a full answer (because we ride at different intensities) you would also have to include a test with different levels of HR because HR is not linear with O2 consumption. So do tests below first lactate threshold turn point, then tests at lactate threshold, then one above (full anaerobic).
So overall, with the HR data, could you conclude here that the metabolic cost will be pretty small? If large surely this would show in increased HR?
Many thanks. Great work you're doing.
DazO
Great video. Not a mtb’r but a lot to be considered for the road bike
excellent video and insight.
@3:15 The heat added to the air spring as it's compressed isn't lost, the air decompresses almost instantly. Heat in the air can comes from the air can surrounding the damper.
True! But the air can loses a lot of heat to the atmosphere. Ride in mud on a cold day...that mud on the can gets baked to clay pot!
Would be interesting to see what the difference is like on an off road climb, as locked out you're going to have a harsh ride and less traction, whereas open damping will use more energy but more efficiently.....
Great video. When Standing on a road bike you can put more weight on the handle bars more easily. Comparing HR when standing Road to MTB isn't just about the shock. What was the HR difference seated between locked and open? Thanks.
What an impressive research guys. Is there anyone else did further research on your job?
Wow. I was expecting to get lost again …. But this time I understood everything! Well explained. After watching Dylan’s video a while ago I was thinking “why didn’t he just put heart rate against the times?” But I guess presenting the heart rate data against the run times would show quite a low difference probably …. and it would be subject to build up of fatigue during testing. I have never thought before about the power meter reading Vs physical effort cost ….. Having had power meters for a while I guess I kind of linked physical effort with watts …. On any one bike, especially a road bike with fixed geometry and similar road surfaces all the time, then this could be true …. But actually now I understand that this is not the case, especially for MTB where position, geometry and rolling surface changes all the time!
RE; expired gas analysis: you'd need volume as well as oxygen/CO2 inspiation/expiration. One CO2 molecule generated by respiration of glucose does not release the same amount of energy as respiration of a ketone body etc. Even if you assume a "respiratory quotient" you'd still need tidal volumes too. You can already measore CO2 concentrarion quite easily: used in hospitals for 'conscious sedation' sometimes already.
super interesting, and the conclusion makes sense. also feels right. #teamlockout
Another great video, thanks to both Dylan and Peak for continuing to surface up evidence based research that validates the bike industry's assumptions and associated marketing.
Wasn't DJ's HR 4-5 beats higher on his run that didn't have his shock locked out? Either way, good job on the video and it points out that properly devised testing is just as important as doing the testing itself.
Here's a test suggestion: Build an insulated calorimeter ("foam box") around the shock to measure temperature gain of the mass of materials inside the box in order to measure the energy loss. Compare energy loss from open vs lock-out mode. Then publish a white paper. Thanks in advance😊
For me I'll lock out the rear shock on climbs that are not as bumpy and typically I feel way better and less exhausted as opposed to when I'm not locked out. So yeah, this video explains the reason why~
@Peak Torque In the case of diving deeper into the metabolic cost when climbing in a standing position ... What would you think about adding strain gauges to the handlbars? Shouldn't this allow for calculating pulling and pushing forces on the bars, which could then be related to the heart rate? They could then give us some more insight on metabolic efficiency, couldn't it?
Related to your "power meter only measures output power" comment. To take that statement one step further, the power meter only measures your output power at the crank, not the true output power of your legs. An obvious demonstration of this is if you stand on the bike and hop in place without pedaling. A power meter will read zero, but your legs are clearly putting out (significant) power to lift of your center of mass. This energy is dissipated in your muscles and suspension when your center of mass falls. I think this happens when pedaling too, particularly when standing and pedaling it's hard to keep your COM a constant height, and some of this COM-bob energy gets burned in the suspension rather than being recovered during the pedal stroke. Even sitting and pedaling, if the suspension is cycling, that means your COM must be moving up and down, and some of the energy you put into raising your COM gets dissipated by the suspension every cycle.
Another example where the power meter and human effort can be dramatically different - if both feet are loaded downwards on both the up and downstroke (like in the pedaling standing example, if you don't fully unweight or pull upwards on your back foot), the leg on the upstroke is doing negative work while the leg on the downstroke is doing positive work. These numbers are extreme, but say the leg on the downstroke is doing 400 watts and the leg on the upstroke is doing -100, the metabolic cost would be much higher than +300/-0 (~1/3 higher if we assume muscle efficiency is constant, we can't regen negative work sadly) , but the power meter would measure 300W for both. I don't think people pedal like this, just illustrating the power meter point.
Very good point
What you'd need to do is measure the non-tangential forces. I'd imaging that with the suspension open the pedaling action is more likely to produce higher non-tangential forces at higher metabolic cost. That's why, typically, climbing out of the saddle is less efficient - at the bottom of the stroke you're more inclined to push straight down because of body weight, rather than have your body weight supported by the saddle.
After watching GPLama's video on the Dura-Ace power meter test, do you think the discrepancy was down to the bike being in the trainer? I saw your comment about pivoting. Also, do you think the material differences between Ultegra and Dura Ace will make a difference? Still considering the Shimano PM cranks, but I'd like to see more testing and reviews. Thank you!
It would be very interesting to do the same test (standing is useless for mtb) but with 3 different bikes with different levels of AS, measuring time and HR, with powermeter constant. High AS bikes are always thought as efficient pedaing bikes that don't need the lockout but the force transmitted from the chain to extend the rear suspension has to add to the total energy used. Also considering that high AS bikes use their chain to fight off bob when the shock is open, you may see differences between open and locked while using your powermeter.
@Peak Torque this is a very valid suggestion about analysing results for different pivot kinematics, I'd love to see this test.
Also when i watched both your video and Dylans Video, I cant help but think that there is a flaw in everyone in the cycling world thinking iso-power is a the "best" control method. I understand that a comfortable sub threshold power makes it repeatable and reduces fatigue for the repeat runs. but as you find, put same power out you get the same times.
In my opinion Power is a more suited to measure difference, and not be the control.
To me this question is about rider efficiency, and as you point out thats metabolic efficiency then riding at HR threshold or consistent HR may be more relevant? Or maybe even ignore the climb factor and just have a set 5-10 minute gravel road or tarmac loop and do all out TT?
If you put force sensors in the saddle and stem, you can probably calculate power used without gas analysis.
There have been lots of tests in the past proving that open suspension does not lead to power loss. It seems the industry forgot for a while, and then all these XC bikes started coming with lockouts again.
The suspension movement does dictate the rhythm of the pedaling. If it's counter to how you would like to be pedaling, increasing compression damping or fully locking it out can be beneficial, not for efficiency, but for the ability to hit the highest power numbers. This is most often felt in a smooth pavement sprint to the finish.
nice testing, thanks. How about a bike with front suspension only? I have a Canyon Pahtlite 6 and it has a 75mm front suspension fork. I use it for road and light paths, but mostly road (of variable quality). Should I lock the front suspension when on tarmac? I like to keep it open but my brother tells me I should lock it when on tarmac. However, there is the video of Dylan Johnson you mentioning, indicating there are studies where locking/unlocking your front fork makes no difference in your performance at all. I mean FRONT fork only of course, no rear suspension or anything like that
Love this type of detail and very much appreciate the time investment to pull this off but, the bigger use case that racers are looking for a major advantage is the full gas sprint for race starts and full gas sprint finishes where the watts are much higher and the new technology in shocks and forks might not filter out like the lower watt stuff of a seated or standing climb. When you are trying to get a great single track drop in position from a mass start with a long open start sprint would you see an advantage with a rear shock lockout?
It would be interesting to compare ftp test results on both locked and unlocked suspensions. The difference between the two would give an idea of the decrease in metabolic (upstream) efficiency.
You're back to measuring at the pedal. It's like taking an ftp test with the bike in a different gear.
@@stevemurray710 When doing an ftp test you are limited by your metabolic threshold, which can be considered as the "energy input" into this system. Applied to the unlocked suspension bike, this same threshold limitation will result in a lower power outpout at the powermeter because the lesser efficiency of that system, as opposed to the locked suspension. How much of an effiency decrease is the big question.
@@Tricombined Correct
One way to think about this is if you replaced a the cranks with a 300W motor, the bike would go the same speed no matter how much you bounced up and down on the suspension. The energy you waste bouncing the suspension is separate from the 300W going into the chain. Was there any difference in heart rate between locked and open runs? That might give some insight into the higher metabolic cost.
Great point!
I could tell that it had something to do with how power is measured between the cranks and rear wheel but I was still surprised because I thought that all this motion in the frame would impede the bike movement somehow. Like a spring that oscillated back and forth while moving in a direction parallel to the oscillation, I thought maybe it would add rolling resistance or something. I figured that in one half of the oscillation the back wheel would be "pushed" back thus impeding its movement. Then again I guess the other half would pull the back wheel forward canceling out the effect?
Fun & interesting experiment, would be very interested in being able to truly quantify the open v locked question, personally I tune my suspension to work for me (at least I think that) on climbs. On dirt say a 50km ride with 2000m climbing, I feel less drained and put in faster times with my suspension open the whole time, if it’s locked out for climbs I find myself very fatigued from the harsh stiff ride, and can get caught out by a technical feature, in the end do I actually burn more fuel open or closed 🧐🤔 🤷♂️
Thanks for the video. I have two (probably dumb) questions. 1- Many mountain bike climbs are 15% to 30%, would the outcome be the same,? 2- According to your test results, would this mean that road bike rigidity is overrated?
Yes, the value of road bike rigidity has been debated for decades.
well in order to compare road and mountain bike in climbing efficiency they should be the same weight. There are also stuff like tyre width and body position, which influences bike efficiency on tarmac climbs.
Very interesting. Would using a power meter at chainset and hub to compare mechanical losses be useful?
I suppose if there was a way to replace the human with an engine where you can control/measure the power output you could then measure the loss.
I think you could make a reasonable approximation of metabolic cost by measuring expiratory volume (spirometry) or respiratory rate (heart rate monitor).
Sooooo we need hub based power meters on mountain bikes to compensate for the suspension losses and get accurate power output readings? Like crank vs wheel HP in cars?
Smart! Same power into that chain/crank HAS to result in same speed (aerodynamics held constant)… basically comes down to wrong test! Test used is incapable of getting the answer we want!
Best video on CZcams
Can't heart rate be the a rough measurable metric to decide how efficient each suspension setup is? In theory if some activity is harder for your body, your heartrate goes up, if you maintain said load. You can also base your load on certain heartrate.
Road bike idustry - proud to present next year model rigid frameset, that get 4.7% stiffer
MTB idustry - there is no time loss between locked and unlocked suspension
If the maximum amount of human power output is fixed and is assumed to occur at maximum heart rate, then you should be able to see power lost as velocity delta of the bike over the distance traveled during a maximum sprint (Power = Force x Velocity). Measure bike acceleration with an accelerometer at maximum heart rate and integrate to calculate max velocity along with directly measuing bike velocity and you'll have your answer. Conduct the test over a few days alternating which variable is tested first.
I´m not a scientist nor engineer but when I think about it. Does it matter if it is locked or not when power is measured on the bike (spindle, pedals or cranks)? Power applied is going to be transfered via chain on the rear wheel anyway. If you could measure power from legs (hip- knee-ankle linkage) and testing terrain is very rough so suspension is actively changing biomechanics of your stroke then this would be the place where power loss/gain could be found. Just an idea.
It could have been interesting if have added your heart rate numbers to the power spreadsheet. It could show some of the differences.
The conclusion must be that powermeters doesn’t work for mountainbikes, your have to use a heartrate monitor.
Try a test of peddling up a bumpy gravel road or single track. I’d wager the metabolic cost is less with the suspension open because the suspension is absorbing the trail chatter instead of your body.
Maybe the downstream power efficiency is higher with the suspension open? The rear wheel is transferring the crank power better with a suspension.
Did you do all this on-road? I'm surprised locked-out didn't give you a bit of an advantage there, but watching the seated shock movement you can see anti-squat is essentially dealing with it fine. I think if you repeated this over more rugged terrain you'd see an advantage to climbing "open", because you don't lose as much energy getting the bike over terrain features.
Did you do a HR comparison of seated effort open vs closed? I'm not surprised standing felt inefficient, you're fighting both the shock and the fork then.
Yes HR is toward the end at 16:11. Yep always open for technical climbs, closed for smooth fire roads. Lockout fork when standing (if possible)
Peak Torque: Riding on enduro bike in lycra.
GMBN: Wait, that's illegal!
I am wondering if the results would be different on an uneven surface.
Ooooooh we're just missing hambini's PowerPoint's pen and we're in CZcams's cycling dream.
Would love to see a test of climbing efficiency on a “brain” shock like specialized has vs a hard tail
Quick someone take shots for how many times he says “peak torque”
Is it generally true, then, to say that the same wattage will always be metabolically more taxing (calories/watt) when standing vs sitting, even on rigid frames like road bikes?
What if you're not adapted to climb suspension open so your metabolic efficiency was lower? Maybe it's more efficient for a rider who always rides unlocked?
Great jersey! Where it can be bought?
I think the only way to settle this is to hit the hill climb every day for about a year and time how long it takes to see which you can do faster.
1/2 way through I was wondering about how your HR was behaving in the different tests. As well as wondering when the baggy vs lycra police would start a debate in the comments...