Tyre Pressure Science! How to save 74watts (@40kph) of losses in road TT triathlon
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- čas přidán 30. 12. 2016
- PART2 is now out here: • Tyre Selection Science...
Save up to 74 watts of losses by paying attention to the science of bicycle tyre (aka bike tire)! If you doubt you could save 74w try putting a old worn narrow almost flat tyre on your front wheel and tell us how you get on! [most tests carried out at 40kph]
Savings are: 10+13+27+20+5+3+6=84w but I took off that first 10w and it is mutually exclusive with the 13w.
links:
Tyre Pressure Calculator goo.gl/QoMv5P (google account needed)
or APP for mobile phones is here: goo.gl/UevARb
Please check out our training plans on fft.tips/peaks (or www.cyclingapps.net/shop/shop-front/). Part 2 of this video: czcams.com/video/2Ps4dfgxGAQ/video.html Part 3: czcams.com/video/CqwFz8z7nsM/video.html
These are materials that can't be found in Romania at all !!! Bullshit ! 😡 That's why , we roumanians, we stole bikes from Europe !!! And we can't do maintenance on them cause of ridiculus corsts of them !!! On short: To Hell with stupid ecology !!!
15:35 You're so wrong on tire weight. BY ALOT !!!
If I lost 74W then i would be riding backwards
Daniel M good one.
@@carlos.5290 good one
you mean upside down
😂😂😂
🤣🤣🤣
I'm in shock. I just used 74 watts to get all the info in my head. How it's possible a human brain be able to store so much information? Jesus !!!! Thank you for sharing the video, now going to watch it a couple more times 👍👍👍
nice video. I like seeing all the supporting data. Thanks for this.
riding my old mtb on the roads here it seems to be best between 50 and 60. beyond or below and I get the issues you described. good info!
The Paris-Rubaix training wheel had me laughing out loud for 30 seconds. 🤣I nearly missed it and had to scroll back to see it. You should’ve left it on screen for longer. 👏👏
"Paris-Robaix Training Wheel" at 4:00 gave me uncontrollable laughter
Yep I know when I've pumped my tyres too high. I get this fantastic 'popping' sound. Damn it !!!
Can't thank you enough. Terrific video from a variety of sources wonderfully dissected and summarized. Would love to have had access to this data when I raced TTs many years ago. 18 mm tubulars pumped to 160 PSI -- ouch. Makes me wistful though. Reminded me of Bob Seeger's line in Against The Wind: "Wish I didn't know now what I didn't know then" (smile).
Thank you for the great feedback!
Great job! I love the way you are actually looking at this scientifically and thoroughly. I like the way you cover a lot of ground clearly at a fast pace - we can always replay if we need to go over something again. My only small criticism is that I think you should have muted the sound of the video you showed at 14:15 because it was a distracting. But overall, a top video! Thanks and I have subscribed.
Great information, You answered some many questions, Thanks for the fast pace, you kept me engaged. I will recommend you're video to friends. Now I'm off to the tire store.With knowledge.
thanks but check out some of your more recent videos! like fft.tips/vsurface
Love your channel, do I understand it all no but you break it down so that I do so thank you very much for all that you do!
SeaSky
Not accurate #6 Tyre Weight 00 watts - Heavier tyre makes you pedal harder than lighter tyre. It is the same scientific fact about heavier rim needs more energy to rotate it every time.
Am I the only one who thinks in the Fast Fourier Transform when see 'FFT' instead of the name of the channel?
Pablo Briz you might be the only one with that acronym!
@@Fastfitnesstips I did elec eng. I thought it too.
Me too!
i love scientists, you did not even try to explain the difference between tubular and clincher, jet i understood within 5 seconds, while other people failed to explain it... Scientists have just so much cleared thoughts and expressions, love it great video!
Wowzers, lots of good info, I’m glad I’ve got the contentental 5000 25’s that I run at 70 psi and yes I do feel them ride fast on my carbon Roval 35 rims
70 psi on 25mm tire, are you kidding me? you should be around 100-110 depending on weight lol
Very informative, but too fast in talking & in presenting background data. Will be better if you slow it down since audiences are not the same and native in English.
Will be nice if you can delve into mtb too.
Fadil Aziz i believe youtube provides a setting for you to slow down a video playback speed and also subtitles. Maybe that would help you ?
Yes he does talk fast but i believe that was self explanatory due to his channel name. “Fast fitness tips”
youtube player gear icon - choose playback speed 075 and you have your slower presentation. You'er welcome.
Fadil Aziz Yeah. Maybe next time ease up on the coke before making a video.
I love this. Cuts out all the BS and myths about wheels/tyres. I completely agree that the science backs all of you major points, and I even learned a few new things. If I had watched this a couple of years ago, I could have saved a LOT of studying myself.
Thanks for the video, great detail explanations!
Josh Poertner is and has been an incredible asset to cycling. Absolute legend.
Probably the most educative video I've watched in a long time.
Thank you.
You can either have a tyre pressure too high or too low so you cannot add them. Good overview about possible power savings or losses, respectively though.
I was just thinking the same
Exactly! Very useful otherwise.
He didn't add them. He said you can only have one or the other.
He was telling that he was not doing that at the end.
it can happen, say you're running on different surfaces on the same run.
Matching tyre width to rim width will have an impact on aerodynamics as well. Putting a wider tyre on a narrow rim is actually going to increase the drag. Not sure if you touched on that. Interesting video
Quite true thanks!
Rixter i believe this whole wider rim thing is more about changing the shape from a teardrop to a more round shape to copy a tubular profile. To me Tubulars are still the gold standard, ride them they are lovely. changing the shape of the tyre will make it proform different. Remember that with clinchers you can't just put wider tyres on a smaller rim as the tyre shape changes, why the wider rims for wider tyres. With tubulars it doesn't make any difference as the tyre will always be round.
These are materials that can't be found in Romania at all !!! Bullshit ! 😡 That's why , we roumanians, we stole bikes from Europe !!! And we can't do maintenance on them cause of ridiculus corsts of them !!! On short: To Hell with stupid ecology !!!
I am so glad that I can keep my tubes forever.
Lots of good information here. But remember that safety and durability of the tire (and sidewall) is important too. I have HED Belgiums and use 25mm Continental GP5000, which works great, but they are hard to get on the wheel. How the tire mates with the rim matters, but don't get a flat unless you have a support wagon.
Great video. But what about these:
-Wheel truness lateral
-wheel truness radial
-wheel dishing
-spoke tension?
All Variables that play a part as well. Rotational weight, Hub LP vs HP, bearing efficiency,
Are we also going to include fork dynamics with the wheel ?
The same wheel in different forks with different tyre clearances, shape of the fork, angle etc
duh, moisture in the air and road surface?
Sir, You put top quality content out there! You gain another suscriber right here. Keep up the good work!
Great video but... surely you can't count tyre pressure savings twice? You will save energy if your pressures are too high, or are too low, but pressures can't be too high and too low at the same time. Ergo max savings are 61-64 watts
You are correct see 22:20; (10+)13+27+20+5+3+6=84w but I took off that first 10w
Spirit in the sky
Ha ha ha ha ha ha ha...
although unlikely, you could have different pressures at front and back, in which case you average the savings. Plus, if the weight is not evenly distributed, inflating the front less should be the case. What was not mentioned was the turbulence caused by the thread of the tire. Also, the droplet shape works when the front of the tire meets the air. It does not work when the rear of the tire meets the air. Another thing not mentioned is the turbulence of the spokes as the rotate, which like the thread work against you. Finally, do not forget the mudguards. The turbulent airflow is compressed between the tire and the mudguard, causing further resistance.
Yeah I do agree... There are 74 watts can be saved but it doesn't mean we will go 74 watts faster. Nice video though, very informative and very useful.
My feeling told my that Conti 4000 S2 is great tire. Best I ever have. And it is not just rolling resistance. It is about comfort and cornering. Maybe there are better tire for me, but I didn't found them. And Conti lie about width. My 23 are actually 25mm, and 25 are 27mm. So there are not perfectly fit on my narrow rims. But my rims are old and heavy just like me. No tire can fix all that problems.
The GP 4000 are a good tire until the sidewall blows out for which it is known for. It happened to me when I took a corner. Even though I am a Clydesdale, it should not happen.
Rak Rakovica gp4000 are great all round tyres, but are not that comfy. if you ride top level cotton or silk tyres you will see another level of comfort.
"Rolling impedance" is my wife telling me to mow the lawn instead of riding. "Rolling resistance" is belly fat.
HED do research into this, it's well worth watching what they say about pressure and how it relates to rider weight, tyre and rim width, as well as riding surface.
Very informative thankyou!
Great and simple information.thanks
very informative. thanks.
Great speech, need more people like you, not text screens after camera
Thank you!
Great infos, thx 🙏
EXCELLENT technical content !!!
I Watch This FFT Video at 0.75 speed in order to slow down the announcer's speech. Much more understandable !
Great video as always. I agree with the summary on clincher vs tubular, I run both and find little difference on road between say corsa evo open vs tubular, they are effectively the same, especially if you use a latex tube in the clincher. However, tubular does help with one of the other goals /savings, that is low pressure - I find it easier to run low pressure on tubulars as you do not get pinch flats, which for me is most of my flats. And if you are racing cyclocross, tubulars are even more important with very low pressures
One of your links says there is no disadvantage to tyres as big as 32 - So i will find out soon when my 32 gatorskins arrive!
Interesting thanks. Good luck with the 32s but careful though because gatorskins have not done well in most tests.
Fastfitnesstips - yes, the gatorskins are just for touring on a crossbike, just hoping they would be too slow in the largest size, they should be fine. Racing is on vit. corsa evo
Hi JB, you should try 4 seasons, they come as 32mm too but much better /higher quality.
These are materials that can't be found in Romania at all !!! Bullshit ! 😡 That's why , we roumanians, we stole bikes from Europe !!! And we can't do maintenance on them cause of ridiculus corsts of them !!! On short: To Hell with stupid ecology !!!
5:30 "Wow! That's amazing." *awkwardly point at air* I died of laughter. So cute. Good video, pardon my amusement.
Great video, bookmarked! I do have a problem with the prevailing idea that wheel weight doesn't matter though (the maths and the explanations don't make intuitive sense to me at least!).
1. driving a car in town you get hideous mileage, I get maybe 2/3 to 3/4 of what i get bombing along UK A-roads. If you watch your litre/100km dial you see the massive amount more energy required to pull away. Remeber this is in town never going more than 30mph (kinda!), even when you have to brake down to 20 then gently raise back to cruising speed it drinks a lot of fuel. Bike speeds and accelerations are really not that different in town, in fact, bicycles usually pull away for the first 10 to 20 yards. When you compare the power to weight ratio of my car for example; 151kW/1650kg compared to me on my bike @ 300W/85kg, makes me wonder how energy sapping those fractions of a second (don't believe that) are and how they affect the overall ride time.
2. The explanation of the racer who used the heavy rims (a) he's racing not riding around town stopping and starting and (b) if your wheel contains enough energy from the weight of it's rotational force to roll you up a hill, then that has to be quite a lot of energy in that wheel there!? The argument that once the wheel is going then that energy is always returned is bunkum, it disappears as heat in your brakes every time you hit a junction or set of lights, and it's fighting gravity every second you have that energy built up in your wheel.
3. I don't have much faith in that Alex Simmons comparison with the different weighted rims either, (a) the heavier wheel was more aero than the lighter wheel so you have two variables there (b) the test is short doesn't expose how much of a difference these increased efforts to overcome inertia may have on an overall ride (c) the difference of 250g is quite negligable where it is easy for some people to save 1000g by upgrading wheelsets if they're currently on beasts like mine (d) the numbers were generated by a theoretical formula, I have just been reading a piece about a solar-powered water-purifying device which (bear with me) the efficiency exceeded the theoretical yield, it's a rare thing but there are plenty of unrefined formulas out there.
If this is all confused bs could somebody pls put me straight, before I go and spend dollar on some lightweight wheels!
A good explanation from another cycling scientist (czcams.com/video/0QDnUkUaQfk/video.html). But you are right. The moment you break you loose the flywheel effect accumulated on the wheels.
so much time, so little riding ? Thanx for all the info and data !
Great video. The power savings, are we talking about them at the same speed so theyre comparible? If so, what speed?
Most tests carried out at 40kph but Knight industries tested at 30mph and Tom Arnalt 35kph
Great video
If its good enough for Fabian Cancellara, its good enough for me!
Thank you! Swapped the tires, and adjusted the pressure according the sheet. The bike was flying after the update 😎
IOS 13 update 😆
You can't have a too high and a too low pressure at the same time. So why would they be added up?
Because clickbait.
My bike has two wheels so you could.
You didn't watch until the end or added it up did you?
Thanks for the video, great summary.
Any idea how significant the interaction of the wheel with the front fork Is? Ie. Cervelo states the P2 was optimized around 23mm tyres, so could an 808NSW mated with 23mm tyres be faster to an enve 7.8 with 25mm?
I don't have any data on forks but the effect of forks alone is likely to be very small esp at 0yaw. You'll notice some manufacturers have gone very wide and some very narrow with forks trying to get aero advantage. If anyone has any data on this, maybe they will comment
Maybe one day you could cover tire width relative to wheel depth in terms of "power savings" assuming the tire width and rim width are equal.
Haha, I was going to write you that you made a mistake by thinking that it's possible to commit the too high and too low tyre pressure mistake at the same time, but at the very end of the video you noted it that it's either one or the other. :D
Seems like mavic know a thing or two when they desiged their cosmic pro wheel/tire combo.
Nice,. I pump up pressure on climbs, and lose tire pressure on descent around 80 psi
sweet video
considering getting latex tubes for my race wheels then. Train on wide-boxy 32 spokes with gatorskins and race on 303's with véloflex corsa.
I'm all for wider tires but on a wide rim isn't a 23 better shaped than a 25 because at some point the tire gets wider than the wheel (maybe at 28-30)
cheers
I was amazed how much Gatorskins slowed me down. I switched to GP 5000 and it was like putting a turbo on my bike. I picked up 2 mph on my average mph and have not rode one ride below 19 mph average since I bought them. I ride recreationally 2 to 3 times a week with no road hazards. I do not commute with my bike but understand why people run Gatorskins for their puncture resistant qualities.
Did some work on trying to create a tyre pressure spreadsheet myself a few years ago. Using bike weight + rider weight + weight distribution. Wanted to use tyre volume rather than width though to get it to work across road and mtb. At that point my rusty physics and maths started letting me down. Would be interested in your view to this approach.
Have a look at both XLS spreadsheets for tyre pressure. The volume one is a bit complicated. Do you think it is useful to have the exact tyre volume?
Ceramic and hybrid ceramic bearings definitely save a considerable amount of energy, but how much depends on the OEM bearing seal type, ball grade, ABEC precision level, ceramic ball type, race material, and type of lubricant. I even have data that shows a tungsten disulfide coating applied to bearing races will save up to 5w. I sell hybrid ceramic bearings for ebikes that improve the range up to 20-25% with the full kit and a *lot* of data to back it up 🙂
Regarding tire compounds to wattage on a TT course. It's not the time on the course that gives a better result for a lower power rider, it's that the saving in watts is higher as a percentage of the riders wattage output.
Excellent video, thanks!
After more than fifty years of riding bikes, I had worked out that the lowest rolling resistance for a 63 kg person on 700c by 25 tyres is to be found between 90 and 95 psi.
I never believed the highest tyre pressures helped beyond 100psi. Not much science involved, but simply years of trial and error.
Currently using Michelin Power Competition tyres on a 35 year old Carlton on modern Ambrosio [ally] rims on Super Record hubs from the 1980s. A very free-rolling combination ... Tyres inflated once a week to 95 psi.
I don't have any science or math to back it up it also seems like running slightly higher pressure on the rear wheel is also optimal, e.g. 90 PSI front 100 rear, because there is typically more weight and force exerted on the rear tire, so the front will lose energy "bouncing" slightly more at the same psi... in my experience, on 700x25c and smooth roads, the ideal seems to be 90 front / 100 rear.
@@timeslowingdown is this the same with tubless?
@@smallnuts2 Not sure, I've never used tubeless before
I like it, thx
i ride lower PSI with larger tires which absrbs vibration which was shown to speed you up a lot. Its not about watt savings its about vibration dampening.
Wow great content! Did you study aerospace/aeronautical engineering at Uni? I do physics A'level and am seriously impressed with your understanding and knowledge (way more advanced than my course)! Also the language you used was very good not just those buzzwords that GCN or bike radar just throw in whever they talk about tech
Thanks I did physics and maths A level and medicine at Uni! I agree its good to avoid jargon as much as possible and keep it practical or applied to the actual riding/event
Not sure if sarcasm or not.
Awesome Information, I pumped my tyres before today's ride since I leave them super low all the time haha. However, 100-110 psi sounds a bit high for the recommendations that I have received before. Is this for a 23c clincher tyre? I would assume that a 25c or 28c would allow much lower pressures. I run 25c at 75 psi at 64 kg at the moment
It depends on road surface so tricky to be too prescriptive for you, but if its regular tarmac road I'd give 85psi a go and see what you find!
71 kg rider on a corima disc wheel with a 25 mm vittoria corsa speed G plus tub, what would be the option tyre pressure? love the info, brilliant videos top man!!!!!!
Thanks! Front 78.9psi Rear 87.4psi typical ( or try 82.8 / 91.7 smooth tarmac 71 /78.6 rough concrete)
Good video - lots of great information. Would have liked the data to be presented longer instead of flashing it on the screen. More time is needed to see and digest the numbers - had to pause often to look at data. Thanks for your summary and presentation!
Thanks. we do this intentionally to reduce the total length of video. Get ready for the pause button again this weekend. New video coming! ;)
massive case of theory not adding up in reality. You cannot make a 74 watt saving just with subtle changes to road wheels. If you add up all the potential gains from a skin suit, aero helmet, shoe covers, optimal body position and aero frame, I would save 150w. That means I can go from being a hobby rider to dropping chris froome. Not happening. This just doesn't add up like that in the real world, maybe I can save 15w at 40kmh.
I think if he laid down the facts with a nasty beat, wore a Zoro mask, and flip flopped on supporting and opposing con artists like Durianrider... then you might have liked the video more.
Beyond that, VegtableFootsoldier, you are an idiot that makes clown videos, filled with hyperbole. Good on you.
The assumption is that (with the right training) you can put out 80% or 90% of the power that "Froome" can put out. Which isn't that hard. The hard part is doing it during the Tour at 98%+ when your rivals attack you.
These numbers are very speed sensitive, many of them depend on you cruising at ironman speeds.
This is why grams of force are a better unit for comparison, but only when the wind tunnel air speed is quoted, or total rider/bike weight respectively.
you are 100% correct, if we did this video again, would put in a speed/watt saving converter
Optimal tyre pressure is calculated for a given rider + bicycle weight and It depends on the air volume (i.e. tyre width). Optima pressure for 23 mm wide tyre isn't the same as optimal pressure for a 25, or 28 mm wide tyre.
So a 100 kg rider with 23 mm wide tyre will have a different optimal pressure than a 60 kg rider with 23 mm wide tyre, or a 100 kg rider with 25 mm wide tyre.
How to calculate optimal pressure:
www.bike.bikegremlin.com/2015/12/23/pressure-i-inflate-bicycle-tyres/
Terrific thanks. Is there a profile that gets you up these dratted hills here faster when you're grey haired & 23 pounds of fat overweight. What if I remove every 2nd spoke & ride bald tyres to cut weight & save money. Please review in technical video.
Very interesting. I would like to see a similar video for my main interest, mountain biking. Thanks.
Hi, great video, very well explained. I'm just wondering why some of the biggest tyre brands didn't make it to the test/comparison (Vittoria, Michelin)?
Most likely because they haven't put their data from aero or CRR in the public domain (unless I missed it)....but didn't I give I shout out to Vittoria at 3:20 for their awesome graphene additive?
Radim Vavrecka Veloflex
Wayne Proud: Veloflex and Vittoria is actually same shit. Vittoria moved their production to Thailand, then some of the old Vittoria-staff re-opened production in the old facilities in Italy and branded it Veloflex. Said to be good tires, though.
They are much better than good. They are brilliant and if you are patient, can be got in bulk during sales. So instead of £58-65, I got 5 of them for £44 each .
So, I've done most of the things you mentioned plus extra. So I guess it's more hardcore intervals.
Wait we have a few more tricks up our sleeve coming over the next few weeks! ...but yes training is key.
Yes sir, I just learned from your other video about saving 30watts from chain. Time to clean it up.
Hi, i've looked your videos and i'd like to do my compliments to you because the argoments are very interesting and well described. I was cycling road bikes for several years and i agree with you about pressure tire( too many people run to high ant others too low) . After injury i switch to e-bike and after 1 year i'm still struggling choosing which could be the best tire and pressure for a rider about 70 Kg. Actually i run 29x2,60 Schwalbe knobby nic which is a good compromise in rolling resistance considering i'm able to go low when i'm on dirt track and go up when i'm commuting to work. I would know which could be the ideal pressure for tarmac, on the side of the tires tell me i can go from 1,5 bar to 3 bar. In your opinion could be ok run 2.6 post and 2.4 ant? In the next season i'd like also to switch to new Wicked Will tires because the pattern seems to me more compact and could give me more advantage, they produce this tires also in 29x2,40 sizes but from what i understood from your video i'll stick with 2.60 so i could keep assorbion effect from big volume tire. What do you think? Sorry for long message and best regards!
Try https: fft.tips/surface
Another subscriber here.
Subscribed
For U17's in my neck of the woods, alloy rims can only be used for racing. With this in mind, should my U17 son be using sprint rims and tubulars on the track, or say Conti Supersonics with latex tubes, for best performance?
thanks for adjusting the psi with the weight but just to be sure that I understand the formula correctly, +2 psi for each 10 kg = +1 psi for each 5 kg right?
best to just follow the formula as not all the calculations are simple linear addition. thanks.
Great video, incredible math show that some things like tyre weight has minimal effect in performance. I'd like to ask you for the power difference between a road bike (700x25 tyres for example) and mountain bike (hardtail 29x2.1)... How much could the speed difference at a given power on a paved road? Anyone has any idea about it? Thanks for your thoughts
Not accurate #6 Tyre Weight 00 watts - Heavier tyre makes you pedal harder than lighter tyre. It is the same scientific fact about heavier rim needs more energy to rotate it every time.
What about the effects of using sealant? Extra weight vs. savings from no flats? I switched (back) to tubulars last year + sealant. So far, zero flats - even though I have a hole in the rear tire which doesn't loose air because of sealant.
Very good question. I don't think anyone has tested the watt loss of the sealant. Its not really about the weight its likely about the intertia of the sealant and maybe rotational weight. I'd love someone to do a spin-down test with and without sealant. Apparently they add about 100g (see www.slowtwitch.com/Products/Things_that_Roll/Tires/Sealant_Test_-_Part_2_4155.html)
I wonder if I were to use "baby powder" between the tire and butyl tube to reduce the friction?
I like the data collections but the rational could be tweeked much more.
1) you can’t have too high and too low tyre pressure. It’s either one. So add just one.
2) Tyre weight differences is truly insignificant but if tyres were significantly heavier, the effects would speak in long steep climbs.
I would still give a thumbs up.
Just like you can't add saving #1 and #2 at once, you can't really do that for #4, 7 and 8. Because 4 and 7 are a direct result of 8. Or you can't really separate the results of wind resistance from rolling resistance because of shape, unless you do the rolling test in the vacuum.
Was going to say the same. Savings #1 and #2 are a bit more obvious though. You tyre pressure can’t be too high and too low at the same time, it’s either too high or too low so your watt saving is one of them, not both.
Too bad I can only give one thumbs up - awesome summary!
Are these all recent developments in engineering? And would this information be published or kept a secret for professional teams?
Difference in tire width on energy loss to smoothing your ride on rough terrain? I suppose muddy would be best to ask off road riders though. Wider resists better sinking into and being grabbed by loose or somewhat fluid materials. Narrower is probably better for handling on pavement.
I weight around 48kg, I usually go for 60-80psi, the group i'm with used around 130psi! But yeah, still got to drop them lol
hallo Oz cycle.. what about motorcycles? Does it work there or does it fling of site to the high suited of the motorcycle chain?!? thanks for your answer!
Very interesting I'm on 27m wide rims, with 25m tyres, if I switch to 28m I'll loose 2.5 watts as the tyre will be wider than the rim and potentially another couple in tyre aerodynamics. However won't I gain in that I can run the tyre at a lower PSI for the same rolling resistance, enabling less vibrations as I go over rougher surfaces? Essentially ruling out the 4 or so watts loss?
I off road a Land Rover , the advice on tyre pressure was always "as low as necessary as high as possible"
"depending on your weight"... so should i have less or more air if i am on the heavier side? what are the basic guide lines for a 700X25c @ 240#'s?
Holy shit , if I implemented all of these savings I can ride a perpetual motion machine that moves forward by itself . . . Amazing math
very funny!!
in 1997 year i made bike for mtb uphill champ, i reduced weight of bike from 12kg to 8 kg, most from wheels, frame did not tuch, i flew uphill, 2 minutes faster than last year, 700m elevation, 7km trip, 26:31 was time, bike was as wild bull, when i pushed pedal it would accelerate asexploded
Great video, thanks!
Could not find the link to the weight/tire pressure
site. I weight 215 lbs on 25 clinchers and would like to know what the
ideal pressure would be
assuming 20lb bike then typically 97psi front 118 rear on good roads, on rough roads/gravel reduce to 87psi F and 107R; and if you went for cobbles 73F 89 R (see czcams.com/users/edit?o=U&video_id=Clk_LLBYFzA)
thanks! look forward to more videos from you.
Is that 13 watts savings per tire for too high pressure or for the two tires all together.
The only problem with tubeless tires is that the sealant used is only good for 3 months, after which you have to add more sealant which will increase the weight of the tire which supposedly hurts rolling resistance, but you say weight doesn't affect it.
On my touring bike, I had tires that weighed 1000 grams each, I switched to a 550 gram for each tire and there was a noticeable improvement in the speed of the bike.
What's the Mavic tape called that fills the tyre/rim interface that you mentioned? Google isn't helping me
They are called Mavic Blades....www.bikerumor.com/2012/06/26/close-up-look-at-new-mavic-cosmic-cxr-80-aerodynamic-road-wheels/
To your credit. The hidden motor still stands. Pretty obvious
Interesting video as usual, but a question; your 1st graph shows improvements in Crr up to 9 bar (130psi), but later you say 130 is too high and also gives losses?
+Cyclespeed Tours thanks this is not a mistake. This is due to differences in the surface. If the road surface is smooth then tyre pressure can be up to 200psi (the pressure used by Bradley Wiggins in the hour record!) but on rough surfaces rolling impedance is greater than rolling resistance....and power is lost. On some surfaces 60-70psi is the optimum for speed despite what many cyclists say!
OK. I'm looking forward to going from 300W (4.8w/kg) to 410W (6.5w/kg) next season with a clean chain and a set of Zipp 303's with top tyres!! :)
haha, I get the feeling you're already optimized in most areas! 2017 may be your year for marginal gains!
Is the test for the new vs worn tire available anywhere? I can't seem to find it, was it a wind tunnel test or how was it calculated?
on the roller in the lab.
I only have 74 watts.
What happens with efficiency if you put oil between tyre and tube. Not much only so that they don't contact each other directly? In theory frictional losses disappear and there are only fluid losses.
This is a really informative and clear video about a topic that's hard to find accurate info about so thanks! Although I don't think tire pressure too high AND too low should be counted separately as saving watts... because you can never lose watts for both reasons at the same time. The worst case scenario for a typical ride would be tires inflated far too high and you would lose 13 watts, but you aren't saving 23 watts overall, you are saving either 10 or 13 watts depending on which scenario you compare to. This is pedantic nit picking though, nice video.
Thanks fro feedback; yes I didn't add up both high and low together (see comments below).
Oh I see! I should have added it up myself and then I would have noticed that. My mistake.
thanks