The bike industry has such an unfortunate mix of circumstances that leads to so many half baked products and concepts. - fanboys, hype - customer education about complex mechanical problems is difficult - selling features, brands and lifestyles instead of performance - many payed reviews - below average wages in the bike industry (just like ski) deter good engineers, who make more elsewhere - narrow mindedness and stereotyped thinking on the customer side. Its not all bad. There are some great people out there making fantastic products. Sadly they are often trumped by bigger players with more manufacturing capacities and networks.
I'd argue that there's no need for "customer education about complex mechanical problems." Why would a customer need to know more than, "Make sure stuff's tight and service and recommended intervals?" The automobile owner doesn't need to know about variable valve timing, low-speed versus high-speed compression damping or any other complex systems in the modern car; they just drive the things! (Yes, they must check oil and tire pressure and a few other things. Similar to what the bike consumer must do.) REQUIRING arcane knowledge isn't the solution. In fact, doing so relieves the manufacturers of responsibility, placing more on the end user. Not the best result. Designing "stupid proof" bicycle products is. In other words, make sure it can provide appropriate lifespan for its intended purpose, given a reasonable maintenance schedule. Sure, those interested in the minutia of suspension design and everything else can learn all they want and go nuts. But it shouldn't be a requirement for the end consumer.
As a frame designer, thank you!!! I work in other industries besides cycling, but this crap has been more prevalent for years in cycling specifically, Thanks making this video.
Hard to argue with what you said 👍 Part of the "problem" is probably also the fact that only a fraction of people buying bikes ride hard and often enough to wreck those poor shocks inside warranty, so it's no longer the manufacturers problem when they fail, if they had all of the shocks fail, they may have thought something was wrong, and changed the design in the next iteration for example, however the Specialized Double Barrel example seems to say otherwise, they switched vendors and keep using the same shock mount a couple of generations later still.
Great point as I ride hard but my bike is cleaned and checked over and a fresh chain is put on as I run 4 per cassette and hot grease per week. Even though the bike is very expensive lots of parts are very poor but slowly up dated as I go along. Like my shock cassette derailleur seat post wheels seat. As the Roval wheels are total rubbish and went through two freehubs and two sets of rims and two hubs so much so I had to use a second wheel from a Specialized test bike which only lasted three weeks. The only thing that has lasted are the Sram code R brakes but I have used them since they come out on other bikes but the 'rsc' are a lot better. 4 motors as I have just changed to my 4th a month ago.
@@noobsaibot9198 it's just not realistic for the common customer to know all this stuff, even people who ride bikes for a living often don't know it or don't want to acknowledge (see any review on the Sesh Enduro or Stump jumper, they often say things like "most bikes are very good these days, but but a bug brand like Specialized surely has a larger r&d budget than smaller ones, so the bikes should be more refined" which means they either have no clue (I assume they had some failures, but assumed it the shocks manufacturers fault or something), or they are paid enough to stay silent, but I'd rather believe the first one, the guys I watch are pretty genuine, even if they sometimes feel like doing pretty much advertisements.
This so unapologetically engineer and needed to be said. Kudos. I think about this kind of stuff every day - I called out our product development team (potentially career ending move) after being tasked to implement a 3rd revision of a shitty design. Recommended a statistically proven improvement based on our current mfg process (unquestionable) and it ended up being featured in their latest design - fancy that! Sometimes it takes guts and no tolerance for BS to get it done right. Keep it up Steve!
Once axially preloaded (bolted in the frame, is designed correctly), the internal clearance of the bearing will be taken up in the axial direction and the balls will be properly loaded. There won't be any give in the inner race in that case. Deep groove ball bearings actually require this for proper operation and lifetime.
Sounds like the Nicolai/Geometron G1 does things right. Spherical bearings, coil shock inside the triangle, long shock for the amount of wheel travel, stiff and symmetrical frame that does not misalign and side-load the shock, straight load paths. Besides the mechanical advantages, as a bike it works great too. In be4 people complaining that the frame has no water bottle mount - I rather have a frame that lasts and performs 100% all the time. To me it is clear, spherical bearings are the way to go. Like you find in motorsports. In my experience they are extremely durable and quite easy to replace.
The downtube mounted shock is less than ideal. I still remember Commencal claiming they saved ~200g on the downtube tube alone by moving the shock from downtube mounted to the rocker-chainstay design going from the V2 Supreme to V3. Which makes sense, basically perpendicularly mounting the shock to the longest tube is the worst thing you could do, the tube has the least strength that way. The lack of a bottle mount is just an added bonus :)
Thank you for articulating this. I had a theory in regards to vertically mounted trunnion shocks and faster wear, vs horizontal standard mounts, now it’s been expanded to these yoke designs as well.
that is one of the reasons why i love my propain spindrift.and also there are also the bearings that ohlins shocks use insted of the bushings and i think that could also help with friction and flex.
It is refreshing to have a breakdown of the effects on shocks from frame flex and side loads, thank you. Now I can send my customers to this info so I can save some time. This is why I have 2 shocks for all my trunnion mount bikes. Cheers!
After watching this and catching your aside about spherical bearings, I went to McMaster and bought a few to experiment with a trunnion shock setup I am building. Thanks for the great tip!
Thank you for this video, its been super helpful. I recently snapped a Rockshox Super Deluxe Ultimate fitted on a Cannondale Habit. The shock went through the top tube and the yoke through the seat tube, its completley written off the frame. Neither Cannondale, or Rockshox will cover any of it under warranty with Cannondale blaming the shock failing rather than their design. I cited this video and took a number of quotes from it in my argument back and demonstrated that the initial failure plane of the shock shaft was clearly lateral before ultimately failing vertically once weakened. Unfortunately they still only offered me crash replacement frame at a significant cost. The industry needs to acknowledge that there is an issue with coil shock compatibility and certain shocks just aren't fit to be used on certain frames. I'm well out of pocket and won't be going anywhere near a Cannondale in future, despite it being one of the best frames I've ever ridden.
Brilliant video. This is an issue that needs attention, and certain frame manufacturers know this, and even worse, some companies (I think we all know one big company that we see a lot of these failures happen on) chose to just kick the can down the line and let it be someone else’s problem. Thanks for speaking up.
Specialized Kenovo 2020 doesn't like coil shocks as the frame forces the top shock mount to move, and I went through 4 full factory shock body rebuilds as cracks on top eyelet oil leaks, also shock shaft on 5th bent, so much so Specialized do not fit coils on there Kenovo anymore. It cost me a couple of grand postage service calls etc. They then give me a Fox 2021 X2 air and that has been great but just sent that after 125 hrs and coat me £180. Now the teflon bush used are fit and forget but I now run needle roller bushes and it lets the shock be less fixed. Good video. I fitted the coil conversion on my Factory 36 a couple of years ago and was very good.
Thanks for the insight Steve. My trunion mount DHX2 has the said issue on my ebike, premature wear on one side of the shock shaft from sideways forces. Perhaps the original style of shock mounting would mean wearing out cheaper readily replaceable bearings at the connection point instead transferring the forces onto the shock.
Great video. Some companies are doing something about it. Cane creek for example modified their eyelet design to create their “yoke approved” db inline version. No thanks to us stumpjumper owners blowing up shocks on a monthly basis 🤦♂️
I was going top write a tale about how i had to modify my suspension linkages because of too tight bearing fit but it just got too long. So this will suffice. Basically as standard it was like riding with seized bushings. I took to it with a socket, emery paper and a steady hand and now I have bearings that turn for smooth suspension operation. Oh yeah, my shock (trunnion) is fine so far.
@Vorsprung Suspension... Truth be told, shock durability isn't something most bike designers design for, it is usually an after thought that gets addressed in a second or third update of frame a design. This is one reason you want to go with a full suspension bike design that been around for a while and had the bugs worked out of it.
The only bike Ive owned that didn't eat it shocks was a 2017 Commencal and it had a shock yolk. I've owned a few Specialized bikes and I they were so un- reliable just because of the constant rear shock issues. Worst of all shock issues was a 2017 Spartan that tried to kill me, burping air on the way down the trail and dangerously lowering the BB height. I actually got some great suspension advice from Steve and sold that thinking. Thanks for shedding light on these issues.
Not every bike/shock combination is guaranteed to destroy shocks in 30 seconds even if it does use less-than-ideal construction in some regards - otherwise yokes and trunnion wouldn’t still exist. Most of the time it’s fine, but most just means >50%.
I had 4 trunnion mounted shock failures in the last year. 3 shock failures on a 2020 enduro on a dhx2 and float dhx2. 1 shock failure on a transition spire with a super deluxe ultimate. Before getting a bike with trunnion mounted shock I haven't had a shock failure in years.
The other issue is that most bike designs are 100% baked before suspension manufacturers even see them. Most bike designs aren't seen outside of CAD before 1000's of them show up in the mail.
Great Rant! :D Sometimes i think frame developers are trying to increase rear end stiffness by putting load through the shock. im still riding a specialized enduro 2020 which has a yoke and a trunnion mount eventhough they would've had enough packaging space to fit for example a 216x63 instead of the 200x60
Jesus, now I understand why there are so many people complaining about this bike in perticular more than with others, and those issues are here just because they wanted the bike to look a certain way 🤔
Had this in my 'to watch' list since it came out, without realising it probably applies to the fact I was trying to get shock #5 for a 1 year old bike with trunnion mounts. Add in the supply chain issues and increased demand potentially lowering quality control reduced for the shocks getting to people, and the chances of failure get higher. One of my failures appeared to be the main piston nut coming loose and the shaft smacking into the pile of piston assembly pieces (didn't open as was warrantied), which seems just poor assembly. Other issues have started with the damper giving up, although I also suspect general poor assembly as 1 shock arrived new from the manufacturer with the LSC dial (Super Deluxe Ultimate) having unlimited clicks and no change in firmness. Have we seen shock designs accommodate this extra rigidity and leverage at the mounts? I can't imagine any way for the shaft/seals to allow much flex, but the materials/designs for connecting everything to the mount points could vary.
And on that bombshell, let's have a chat about bottom brackets. *_|- Badum tssss -|_* Bike industry: Nooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo!
You have to include the bearings on the trunnion mount to get a good representation of play. Because there will be play in the bearing just like there is in the bushing.
The trunnion mount on my 2020 Enduro is -way wider than 54mm -not centered with the yoke. Had to shim .020" all on one side to center the shock and get rid of the spacing in excess of 54mm to avoid preloading my bearings and applying side load on the shock
The issue is very simple: many frame designers do not understand the principle of "degrees of freedom". Most rear ends are overconstrained, and in such systems, compliance is achieved by deformation of the weakest link. Trouble with that is that typical tolerances can have a huge effect on the loading of that weakest link. The trunnion design is a clear example of that: we have very flexible frames (their stiffness is at least an order of magnitude less than the shock), with fairly large tolerances, being supported by the shock - which is stiff, but not designed to carry radial or bending loads. Ensuring proper alignment is not feasible in all joints of a mountain bike, so the suspension must be designed to be able to tolerate misalignment. Doing a kinematic analysis of all the joints of a typical mountainbike shows that most components are over-constrained. For example, if the axis of the two horst links aren't coaxial, they will introduce significant loads into the chain and seat stays as the frame moves through its travel. That is a big reason why many frames eat bearings.
I'm curious about design on the Evil bikes with tons of bearings on the other hand my Santa Cruz with the bottom bearing mount has been working flawlessly for nearly a year, all the bearings are solid compared to a Radon I had where the trunnion mount frame was eating through bearings and i had to replace them twice during a year
I'm a bit late to the party, but wanted to add that my Specialized Turbo Levo uses a long clevis, which results in many shock manufacturers advising against using their coil shock on the bike. Apparently the piston rod is not strong enough to withstand the bending moment. There are scary pics on the forum of broken shocks. I'm guessing the resulting crash hurt. I'm still lovin' my Smashpot, BTW. 👍
I'm currently halfway through disassembling a shock from a well known brand, noted for their use of orange, from a 2019 bike that sounds like bumphumper where the damper shaft has sheared in two, in the well of the bearing. That thing is yoke attached & it will be a bill for £££'s to put right. I'm here because I wanted to understand how this could happen.
I bought DVO Jade for my Bird Aeris Mk1 in 2020. In less than a year, I had wear mark on my stantion. It could be bad-ish frame design, it could also be bad shock design, because I talked with few people with the same problem. I was thinking about finding spherical bearing for the eyelets, but I have to get shock with bigger eyelets like canecreak. Im not buying fox, because they crack at the top of the damper. Probably wont get another DVO (I returned my shock, and got full refund).
This is a genius takedown of an increasing problem. Frame designs are pushing to have more and more shock performance in smaller and smaller spaces. You should look at the digit bikes design, I think it addresses this.
What do you think of the Norco Sight VLT's use of a bracket with bearings to get the trunion shock sideways? Seems like it solves the lateral braking forces problem by having bearings in an X pattern. Not quite as good as spherical bearings but better? My experience has been great. 2,000 hard freeride trail miles on mine with one 50 hour service on the RS Super Deluxe. It actually blows my mind I broke the alloy chainstays but the shock is still going strong.
I had a customer who kept bringing his Bomber CR coil shock to us because it was leaking. After rebuilding it 3 times we sent it to Fox. They had a guy call us and asked me if it came off a kenevo ebike - it did! He said "yeah, we see that yoke design crack the shaft on these all the time." I was left with my jaw on the floor; you can't run certain coil shocks on yoke design bikes because they can't handle the side loads! Whaaaat
Judging by my current bike with very similar suspension layout (minus the floating lower mount)it's pretty good in terms of side loading the shock, only issue being *a* *lot* of rotation in the upper eyelet, so eyelet roller bearings highly advised, both for sensitivity and bushing durability.
Good video as always. I just have an understanding question regarding the side loading issues that can occure with extending yokes that have one eyelet rotated 90 degrees: How do they create more sideloading torque than a construction without the yoke? I can get behind the idea that an extending yoke with all pivots oriented in one way (pivoting in the up-down direction) will act as a long lever for side loads. But when using a 90 degree rotated bushing in the middle (where the shock is mounted to the extending yoke) I would assume that the load is the same or even less for a given side deflection on the point where the yoke is mounted to the rear triangle. As the length is bigger the needed angle to compensate the side deflection would be smaller for either end (shock bushing to the frame and yoke bushing to the rear triangle -> The middle one can move freely as it is rotated 90 degrees). I would appreciate if you could explain that in laymans terms! :)
Exactly my thought also. With such a construction you should get " free" rotation in all directions. In the pich axis you have the upper mount, in the yaw axis you have the lower mount and in the roll axis you have the shocks ability to rotate between the eyelets.
@@mikaeljc76 not really, because it's not about rotation, but about bending forces, with a very long shock (a yoke effectively extends the shock length) it wants to bend on itself, that's part of the issue, add to that frame bending side to side, with both eyelets setup 90° to each other, the shock has to bend on itself, instead of at the mount, hope you understand what I mean.
Here's a brief explanation. Start with adding a yoke to extend the shock. Then you have 3 rotation points: the front shock eyelet, the rear shock eyelet, and the yoke mounting points. When those three are aligned, they all rotate in the same direction, so if one rotates, the others can as well, taking up movement without loading anything. Rotate the middle eyelet so it's turned perpendicular to the rest, as is done in the clevis design. When that middle eyelet rotates, the other eyelet and yoke mount no longer rotate with it, because it's direction of rotation is perpendicular to them. That movement has to be taken up somewhere, so it goes into the shock shaft. Bam, side load and increased wear.
@@MrSatchelpack Yes, some are; however, the latest Pivot bikes 2019+ seem to be designed & manufactured well. I would prefer a Trail 429 over a more flexible Ripley frame, with a yoke coming from behind the seat tube. Santa Cruz bikes are some of the sturdiest I've seen in terms of design for the long-term. They're not my style and a bit heavy, but their lower shock-mount is good. The previous design also allowed for both points mentioned here, the upper counter-rotating link is not acting as an extension like in the Ripley.
@@midMTB I think they've vastly improved things but I remember reading somewhere that some of pivot's older frames were incompatible with coils simply because pivot was using the shock as a stress point as a way to reduce frame material/weight, and since coil shocks are less rigid than air shocks due to the smaller stanchion, they were wearing/breaking shocks at absurdly high rates. The newer bikes should be better like you said, but people need to watch out for the older ones.
so im wondering what the difference is between linair and progressive coil springs..all the data is based on a linair spring and not a progressive spring..is there a topic on this issue. i have the option to go with a 60mm rocker but i like the feel of the 65mm rocker, so is my option a progressive spring to make it ride more on top more mid-stroke support?
Hey I'm more than a little late here, but I'll ask anyway: In a yoke mount the eye is turned 90 degrees so the axis is vertical - wouldn't this accommodate MORE misalignment, given the additional axis of rotation? Lateral flex from the rear triangle and yoke itself is taken up in the vertical rotational axis, while the "normal" rotation around the horizontal axis is accommodated at the other ends of the yoke?
Hey Steve. Thanks for your videos, always very informative! I’ve had many DU bushings that were so tight that the axle is completely stuck. Stuck so bad that I need a vice to extract it. This has 3 problems: increase wear in the shock (anodisation inside that is wearing), wear at the frame interface because the axle rotates with respect to the frame, not with respect to the shock! And also the tightening screw that keeps getting lose. I tried IGUS bushing but couldn’t get the axle in without damaging the material. In one old frame I was able to install a roller bearing. On another frame it wouldn’t work so I asked a friend to machine a bronze bushing. Had the problems on 4 separate frames, and with 3 different brands if shocks. What’s your take on that?
You could pick up a 15mm reamer as it sounds like the hole in the shock is to tight? FWIW, Cane Creek used slightly smaller holes in their shocks with their own hardware and standard 15mm bushings don't work in them. I was able to use a reamer and open it up to 15mm by hand.
DU bushings should be quite tight - they do have significant enough friction that roller/ball bearings are noticeably better, but it can be hard to find a high enough load rating for small bearings like that, plus sealing needle bearings is tricky. The Igus ones are usually pretty good though, sounds like your reducer hardware was not properly chamfered.
I've had a new bike where the bushings were so tight that the shock had wear marks after a few hours of riding (from torsion of the shock due to suspension travel). Warrantied the shock through the bike manufacturer, and installed IGUS bushings on the new one. Shock lasted for years until I replaced it by a different model - for an upgrade, not a failure.
Hey Steve, I was wondering if you came across any spherical bearings that would work with a 12.7 eyelet or plastic fox bushing (and 8mm bolt)? I've got a '22 Process 153 with trunnion mount. Misumi probably wouldn't mind taking a custom order... but at what cost, you know. I just wish there were some out there like the DT Swiss Spherical bearings (DCWDXXXXN08079S). but those are 16 OD and 10 ID. EDIT: I drew this up in CAD and using a cane creek kitsuma eyelet (14.7 bushing OD) you could get nominal 1.85mm of plastic bushing material around an 11mm microball w/ 8mm thru hole. Hmmm...
Something you'll see on a lot of bikes is linkages in single sheer which creates uneven loading. If you did this within most engineering industries you'd get laughed out of the office but it seems to be almost standard practice within the bike industry.
Sorry did you say Levo/Kenevo? Specialized frames are killing shocks and the big S is just putting it down to the shocks. Good job they're pitching them at the cheap end of the market eh 🙄 but thanks for making this video and hope the industry listens. I've just put a Jade X coil on my Levo SL which is supposed to be beefed up but we'll see if it can handle it and lasts longer than the last coil shock....
My rear shock is just fine on my hardtail. As for the bike industry, I believe they will never stop pushing tech in the wrong way just because parts don't break enough to justify a drastic change.
Taking an example, is YT’s move to go to a Capra with a linkage-driven shock good or bad? Will it ease the shock’s bottom mounting hardware from rotational forces? (Assuming the linkage uses bearings) It does make it easier to change coil spring on the shock as the shock mounting hardware is not in the way and has to be removed and replaced every time. But does this linkage design at all void use of certain coil shocks such a as the Fox DHX2? (Ibis Ripmo is to me known to not work well with the DHX2. Does it have a similar linkage-driven shock interface?)
@@diamondsink2000 Thanks for the clue. I didn’t know there was a problem. Haven’t heard of it. What problems did it give? Not much rotation there, if at all. Other frame mounting designs have considerable rotation, for example the 90° rocker links. Or am I misunderstanding what you mean?
@@diamondsink2000 Ah ok, I misunderstood you there first. I now get you mean the a bit long 40 mm long lower shock hardware bent. I can see that happen, even if I don’t know of it having happened. Thanks for the info.
Generally speaking no, coil shocks are actually usually worse at handling side loads because the body/shaft interface is less stiff relative to the stiffness of the eyelet.
Can’t you put bearings which are not so rigid in the bearing mounts of the trunnion? Wouldn’t that make the flex go to the bearings ? Might be a dumb question but I’m really curious
Is there any way to soften the impact of these sideway forces? E.g. with some sort of special bushings/bearings? My Specialized seems to be affected by it, it has a yoke and regular bushings (no Trunnion mount), and it appears to have eaten my DVO Topaz T3 in around 5 months. The shock is now losing air, and Im not sure this will fall under the warranty.
@@robertg4249 A Kenevo. It seems to have a very similar yoke system as the older Specialized Enduros, although a slightly different layout (not the "Specialized X" anymore). The new Enduros seem to have an updated linkage design, where the yoke doesn't extend the shock length anymore, so they could be better in this regard? I don't know.
@@piciu256 Do you have any recommendations? Fox now offers a ball bearing kit for shocks, although it seems to be 8x30mm only, and I'd need something for 8x20mm. Real World Cycling has needle bearings in 8x19mm, with some additional 0.5mm spacers, so theoretically it would fit. As far as I know needle bearings are not great for axial forces, so not sure if these would actually help? Also the shipping from US to Germany is a whooping $35. Enduro Bearings themselves, whose bearings are used by RCW, also offer a needle bearing for shocks, however without the spacers, so only in 19mm or 20.85mm, which might or might not fit (and interestingly according to Chris from RWC the development of this product was a breach of an agreement of not offering a competing product). At least this would be available in Europe (once it's back in stock sometime next year). Are there any other options?
@@sp00n I was talking about needle roller bearings, should have been more specific. They do not take axial forces at all, as in they allow the shock to move side to side, I think they could help a little, plus they are way smoother in frames with high eyelet rotation.
How do dirt bike manufacturers go about their single shock rear suspensions? Dirt bikes might not have water bottles to consider, but they do have engines and transmissions which occupy space. Do they just build everything stronger (thus heavier) because dirt bikes are not pedal powered?
Well, there's a few things at play there: 1. dirt bikes are far less concerned with weight - the shocks are very heavy compared to MTB shocks, typically about 3-5x the weight (the MX Tech National shock is renowned for its light weight - usually it's about 7lbs/3.2kg vs MTB shocks ranging from 0.4-1.0kg incl spring) but only having to deal with a vehicle 2-2.5x the weight. As a result, they can do things like use bigger shafts, and make them out of steel instead of aluminium 2. Dirt bike shocks may not be quite as reliable as people often think. Their recommended service intervals are about the same as MTB shocks (actually less in many cases - KTM PDS shocks have a 30hr service interval), and they do often blow if not serviced at the recommended intervals.
I totally agree with everything said! But there is more... The current trend of extremely low and sloping top tubes (for no logical reason, standover height is not an issue that far back) makes it even harder to fit a decent size shock in the frame. AND it makes the frame less stiff of course. And it's ugly. ;-) A funny thing is that it's quite often the large frame manufacturers that produce bikes with yokes. Shouldn't they be the ones that have the knowledge? I mean, a small manufacturer might not have engineers and designers with sufficient experience to avoid flawed designs, and that would be easier to excuse.
It's about the looks mostly, a frame that sweeps low looks good imo, plus you get more standover at once, since the tube goes mostly in a straight direction.
@@piciu256 yeah silly me, a high horizontal top tube straight from the top of the head tube would really enable me to have a 200mm dropper. If i was 7ft tall maybe.
@@lewistaylor1489 first of all we were taking about top tubes, not seat tubes, they are somewhat independent, secondly I'm running a 180mm Oneup post (I could have fitted 190 since the frame has a lot of insert depth) on a frame which many reviewers dubbed as having a "high seat tube" (440mm in Medium) and I'm only 170cm tall, so no, a low seat tube doesn't necessarily all of for a longer post, it does however allow for up sizing, which I'm not sure is applicable anymore, with most bikes being really long already. Great example being the newest Commencal Meta, all the low seat tube does is make it so a lot of seatpost is sticking out of the frame, since the tube bends so close that you would be be able to fit a longer dropper than before anyway (assuming the dropper is slammed, which is unrealistic with how low the seat tube ends)
Your comparison between the trunion mount and DU bushing side flex was misleading. The bearings on the trunion mount will have side play, similar to what you showed with the Santa Cruz specific shock.
It's probably not as misleading as you are thinking though. Say your pivot can allow 0.001" of misalignment through clearances. With an eyelet, that misalignment happens across ~12mm of width. On a trunnion mount, it happens over 54mm. The angular movement allowed by clearances in the trunion mount is significantly less. The same thing also applies to deflection in the materials, any deflection in the 12mm eyelet will allow significantly more angular deflection then the trunnion.
@@dsm156 I understand, just saying that bolting it in a vice was not a very good representation. Next time I remove my shock it will be interesting to leave the trunion side attached and see how much side-play there is.
@@enkie22 once bolted up, the play in the bearings is taken up and it is very rigid. Check it out if you have a bike with trunnion mount - you can easily compare the trunnion end to the non trunnion end and see which end is more rigid.
Why not put a plain spherical bearing at each end of the shock? Plain spherical bearings avoid side load by design, so this seems to be a durable solution for the side load problem. Plain spherical bearing: en.wikipedia.org/wiki/Spherical_bearing.
A few shocks do (Curnutt back as far as about 1999, Cane Creek from about 2004-2009, Ohlins for a couple of years although unsure if they still do, currently Push and EXT), it's generally a good solution, though there are some tradeoffs with weight, wear (which leads to knocking) and cost. However, for sure it prolongs the life of the shocks.
Rear suspension on a bike goes something like "I'll just check how the bearings are, oh look they're all fucked." It's the same problem with those damn chain-wear indicators, when you do go to use them you leave your wallet open on the workbench with your credit card details in perfect view.
Why isn't this more common knowledge? I wonder when people will learn that the more they know about their hobby, the less they will ultimately need to spend?
lol if you have been following hambini's bb roasts you know the frame manus dont want to give a crap about tolerances. #closeenoughisgoodenough there is no way they will put in effort for shocks given what they can be bothered to do for bottom brackets...
"Dear Bike Industry..." could totally be a new series
A very long one!
Excellent idea! Hambini could collaborate with, "DEAR BIKE INDUSTRY 😡😡!!!!!!"
@@dudeonbike800 Hambini is excellent, it's just that road bikes are too boring.
MY COMPLIMENTS! The super thruth about shocks/frames-mounts !!! well said Steve
Thanks for this Steve! Probably like yelling at the void, but it's still good to hear.
The bike industry has such an unfortunate mix of circumstances that leads to so many half baked products and concepts.
- fanboys, hype
- customer education about complex mechanical problems is difficult
- selling features, brands and lifestyles instead of performance
- many payed reviews
- below average wages in the bike industry (just like ski) deter good engineers, who make more elsewhere
- narrow mindedness and stereotyped thinking on the customer side.
Its not all bad. There are some great people out there making fantastic products. Sadly they are often trumped by bigger players with more manufacturing capacities and networks.
I'd argue that there's no need for "customer education about complex mechanical problems." Why would a customer need to know more than, "Make sure stuff's tight and service and recommended intervals?"
The automobile owner doesn't need to know about variable valve timing, low-speed versus high-speed compression damping or any other complex systems in the modern car; they just drive the things! (Yes, they must check oil and tire pressure and a few other things. Similar to what the bike consumer must do.)
REQUIRING arcane knowledge isn't the solution. In fact, doing so relieves the manufacturers of responsibility, placing more on the end user. Not the best result. Designing "stupid proof" bicycle products is. In other words, make sure it can provide appropriate lifespan for its intended purpose, given a reasonable maintenance schedule.
Sure, those interested in the minutia of suspension design and everything else can learn all they want and go nuts. But it shouldn't be a requirement for the end consumer.
Can you give examples of those "great people" out there and their fantastic bicycle products?
Specialized left the chat... (Stumpjumper's blowing shocks - lol).
THANK YOU! Finally someone with a bit of influence talks about this!
Hope this makes it to Pinkbike front page
As a frame designer, thank you!!! I work in other industries besides cycling, but this crap has been more prevalent for years in cycling specifically, Thanks making this video.
Hard to argue with what you said 👍
Part of the "problem" is probably also the fact that only a fraction of people buying bikes ride hard and often enough to wreck those poor shocks inside warranty, so it's no longer the manufacturers problem when they fail, if they had all of the shocks fail, they may have thought something was wrong, and changed the design in the next iteration for example, however the Specialized Double Barrel example seems to say otherwise, they switched vendors and keep using the same shock mount a couple of generations later still.
Yep. That's why regulations on planned obsolescence need to become stricter.
Great point as I ride hard but my bike is cleaned and checked over and a fresh chain is put on as I run 4 per cassette and hot grease per week. Even though the bike is very expensive lots of parts are very poor but slowly up dated as I go along. Like my shock cassette derailleur seat post wheels seat. As the Roval wheels are total rubbish and went through two freehubs and two sets of rims and two hubs so much so I had to use a second wheel from a Specialized test bike which only lasted three weeks. The only thing that has lasted are the Sram code R brakes but I have used them since they come out on other bikes but the 'rsc' are a lot better. 4 motors as I have just changed to my 4th a month ago.
@@Ahaggah No way, shitty products are always gonna be a reality, lets face them ourselves instead of leaving it to the bureaucrats.
@@noobsaibot9198 it's just not realistic for the common customer to know all this stuff, even people who ride bikes for a living often don't know it or don't want to acknowledge (see any review on the Sesh Enduro or Stump jumper, they often say things like "most bikes are very good these days, but but a bug brand like Specialized surely has a larger r&d budget than smaller ones, so the bikes should be more refined" which means they either have no clue (I assume they had some failures, but assumed it the shocks manufacturers fault or something), or they are paid enough to stay silent, but I'd rather believe the first one, the guys I watch are pretty genuine, even if they sometimes feel like doing pretty much advertisements.
This so unapologetically engineer and needed to be said. Kudos.
I think about this kind of stuff every day - I called out our product development team (potentially career ending move) after being tasked to implement a 3rd revision of a shitty design. Recommended a statistically proven improvement based on our current mfg process (unquestionable) and it ended up being featured in their latest design - fancy that! Sometimes it takes guts and no tolerance for BS to get it done right. Keep it up Steve!
Once axially preloaded (bolted in the frame, is designed correctly), the internal clearance of the bearing will be taken up in the axial direction and the balls will be properly loaded. There won't be any give in the inner race in that case. Deep groove ball bearings actually require this for proper operation and lifetime.
Steve, great to see new Tuesday Tunes showing up. Keep'm coming. Love the content.
Sounds like the Nicolai/Geometron G1 does things right. Spherical bearings, coil shock inside the triangle, long shock for the amount of wheel travel, stiff and symmetrical frame that does not misalign and side-load the shock, straight load paths. Besides the mechanical advantages, as a bike it works great too.
In be4 people complaining that the frame has no water bottle mount - I rather have a frame that lasts and performs 100% all the time.
To me it is clear, spherical bearings are the way to go. Like you find in motorsports. In my experience they are extremely durable and quite easy to replace.
The downtube mounted shock is less than ideal. I still remember Commencal claiming they saved ~200g on the downtube tube alone by moving the shock from downtube mounted to the rocker-chainstay design going from the V2 Supreme to V3. Which makes sense, basically perpendicularly mounting the shock to the longest tube is the worst thing you could do, the tube has the least strength that way.
The lack of a bottle mount is just an added bonus :)
Thank you for articulating this. I had a theory in regards to vertically mounted trunnion shocks and faster wear, vs horizontal standard mounts, now it’s been expanded to these yoke designs as well.
I love engineering common sense! Killer job explaining all the variables!
Love this. Preach Steve! Let's talk about leverage ratios and people lack of knowledge about them next. Heavy dudes need to know more about this.
that is one of the reasons why i love my propain spindrift.and also there are also the bearings that ohlins shocks use insted of the bushings and i think that could also help with friction and flex.
Best vid so far, this is so needed! (and in many more ways that just shock mounts)
It is refreshing to have a breakdown of the effects on shocks from frame flex and side loads, thank you. Now I can send my customers to this info so I can save some time. This is why I have 2 shocks for all my trunnion mount bikes. Cheers!
After watching this and catching your aside about spherical bearings, I went to McMaster and bought a few to experiment with a trunnion shock setup I am building.
Thanks for the great tip!
Steve saying what most won't. More of this please
Once again, a top-notch video!
Many thanks for these great infos 🙏🏼😎🤙🏼
Thank you for this video, its been super helpful. I recently snapped a Rockshox Super Deluxe Ultimate fitted on a Cannondale Habit. The shock went through the top tube and the yoke through the seat tube, its completley written off the frame. Neither Cannondale, or Rockshox will cover any of it under warranty with Cannondale blaming the shock failing rather than their design. I cited this video and took a number of quotes from it in my argument back and demonstrated that the initial failure plane of the shock shaft was clearly lateral before ultimately failing vertically once weakened. Unfortunately they still only offered me crash replacement frame at a significant cost. The industry needs to acknowledge that there is an issue with coil shock compatibility and certain shocks just aren't fit to be used on certain frames. I'm well out of pocket and won't be going anywhere near a Cannondale in future, despite it being one of the best frames I've ever ridden.
Brilliant video. This is an issue that needs attention, and certain frame manufacturers know this, and even worse, some companies (I think we all know one big company that we see a lot of these failures happen on) chose to just kick the can down the line and let it be someone else’s problem. Thanks for speaking up.
Specialized Kenovo 2020 doesn't like coil shocks as the frame forces the top shock mount to move, and I went through 4 full factory shock body rebuilds as cracks on top eyelet oil leaks, also shock shaft on 5th bent, so much so Specialized do not fit coils on there Kenovo anymore. It cost me a couple of grand postage service calls etc. They then give me a Fox 2021 X2 air and that has been great but just sent that after 125 hrs and coat me £180. Now the teflon bush used are fit and forget but I now run needle roller bushes and it lets the shock be less fixed. Good video. I fitted the coil conversion on my Factory 36 a couple of years ago and was very good.
Good spot that roller bearings do not hold the shock rigidly in place
Thanks for the insight Steve. My trunion mount DHX2 has the said issue on my ebike, premature wear on one side of the shock shaft from sideways forces. Perhaps the original style of shock mounting would mean wearing out cheaper readily replaceable bearings at the connection point instead transferring the forces onto the shock.
Verry insightful, thank you!
Great video. Some companies are doing something about it. Cane creek for example modified their eyelet design to create their “yoke approved” db inline version. No thanks to us stumpjumper owners blowing up shocks on a monthly basis 🤦♂️
Never thought about that, thanks a Lot for informing me :)
Thanks for educating.
Welcome back Steve, we missed you
Brilliant, Well said!
Very well said & explained sir. 🙌
I was going top write a tale about how i had to modify my suspension linkages because of too tight bearing fit but it just got too long. So this will suffice. Basically as standard it was like riding with seized bushings. I took to it with a socket, emery paper and a steady hand and now I have bearings that turn for smooth suspension operation.
Oh yeah, my shock (trunnion) is fine so far.
good article, I blown Fox trunion shock on my Giant Trance X after a year of riding (got the bike new from Giant store).
@Vorsprung Suspension... Truth be told, shock durability isn't something most bike designers design for, it is usually an after thought that gets addressed in a second or third update of frame a design. This is one reason you want to go with a full suspension bike design that been around for a while and had the bugs worked out of it.
6:06 I guess the guys at Vorspsrung Suspension really like their eggs.
I… have a chicken farm
@@VorsprungSuspension hahahahahah!
The only bike Ive owned that didn't eat it shocks was a 2017 Commencal and it had a shock yolk. I've owned a few Specialized bikes and I they were so un- reliable just because of the constant rear shock issues. Worst of all shock issues was a 2017 Spartan that tried to kill me, burping air on the way down the trail and dangerously lowering the BB height. I actually got some great suspension advice from Steve and sold that thinking. Thanks for shedding light on these issues.
Not every bike/shock combination is guaranteed to destroy shocks in 30 seconds even if it does use less-than-ideal construction in some regards - otherwise yokes and trunnion wouldn’t still exist. Most of the time it’s fine, but most just means >50%.
I've had 3 Commencal bikes, never had a shock issue.
@@mtbohanaI never had a shock issue on my Commencal either, but I did snap the rear axle and go OTB. The next year they used a different axle...
@@ryanautomator5760 Do you know what brand that axle was? I need to stay away from them. I already go OTB with two good axles LOL.
I had 4 trunnion mounted shock failures in the last year. 3 shock failures on a 2020 enduro on a dhx2 and float dhx2. 1 shock failure on a transition spire with a super deluxe ultimate. Before getting a bike with trunnion mounted shock I haven't had a shock failure in years.
"If you're a frame designer, can you please stop doing that?" looooool
The other issue is that most bike designs are 100% baked before suspension manufacturers even see them. Most bike designs aren't seen outside of CAD before 1000's of them show up in the mail.
Great Rant! :D
Sometimes i think frame developers are trying to increase rear end stiffness by putting load through the shock.
im still riding a specialized enduro 2020 which has a yoke and a trunnion mount eventhough they would've had enough packaging space to fit for example a 216x63 instead of the 200x60
Jesus, now I understand why there are so many people complaining about this bike in perticular more than with others, and those issues are here just because they wanted the bike to look a certain way 🤔
Had this in my 'to watch' list since it came out, without realising it probably applies to the fact I was trying to get shock #5 for a 1 year old bike with trunnion mounts.
Add in the supply chain issues and increased demand potentially lowering quality control reduced for the shocks getting to people, and the chances of failure get higher. One of my failures appeared to be the main piston nut coming loose and the shaft smacking into the pile of piston assembly pieces (didn't open as was warrantied), which seems just poor assembly.
Other issues have started with the damper giving up, although I also suspect general poor assembly as 1 shock arrived new from the manufacturer with the LSC dial (Super Deluxe Ultimate) having unlimited clicks and no change in firmness.
Have we seen shock designs accommodate this extra rigidity and leverage at the mounts? I can't imagine any way for the shaft/seals to allow much flex, but the materials/designs for connecting everything to the mount points could vary.
And on that bombshell, let's have a chat about bottom brackets. *_|- Badum tssss -|_*
Bike industry: Nooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo!
You have to include the bearings on the trunnion mount to get a good representation of play. Because there will be play in the bearing just like there is in the bushing.
No, it’s far lower because the bearings are spaced so far apart. Try it in a frame, it is extremely rigid.
The trunnion mount on my 2020 Enduro is
-way wider than 54mm
-not centered with the yoke.
Had to shim .020" all on one side to center the shock and get rid of the spacing in excess of 54mm to avoid preloading my bearings and applying side load on the shock
54mm is the shock width, the bearings themselves can be at 65mm or more - there should be a spacer between the bearing and the shock on each side.
The issue is very simple: many frame designers do not understand the principle of "degrees of freedom". Most rear ends are overconstrained, and in such systems, compliance is achieved by deformation of the weakest link. Trouble with that is that typical tolerances can have a huge effect on the loading of that weakest link.
The trunnion design is a clear example of that: we have very flexible frames (their stiffness is at least an order of magnitude less than the shock), with fairly large tolerances, being supported by the shock - which is stiff, but not designed to carry radial or bending loads.
Ensuring proper alignment is not feasible in all joints of a mountain bike, so the suspension must be designed to be able to tolerate misalignment. Doing a kinematic analysis of all the joints of a typical mountainbike shows that most components are over-constrained. For example, if the axis of the two horst links aren't coaxial, they will introduce significant loads into the chain and seat stays as the frame moves through its travel. That is a big reason why many frames eat bearings.
I'm curious about design on the Evil bikes with tons of bearings
on the other hand my Santa Cruz with the bottom bearing mount has been working flawlessly for nearly a year, all the bearings are solid compared to a Radon I had where the trunnion mount frame was eating through bearings and i had to replace them twice during a year
I'm a bit late to the party, but wanted to add that my Specialized Turbo Levo uses a long clevis, which results in many shock manufacturers advising against using their coil shock on the bike. Apparently the piston rod is not strong enough to withstand the bending moment. There are scary pics on the forum of broken shocks. I'm guessing the resulting crash hurt. I'm still lovin' my Smashpot, BTW. 👍
No wonder my shock has snapped twice....specialized enduro....
Great food for thought
I'm currently halfway through disassembling a shock from a well known brand, noted for their use of orange, from a 2019 bike that sounds like bumphumper where the damper shaft has sheared in two, in the well of the bearing. That thing is yoke attached & it will be a bill for £££'s to put right. I'm here because I wanted to understand how this could happen.
Ha, ha! Why even conceal the name when you go to such lengths to reveal it? Funny though!
Amazing and true!!!
I bought DVO Jade for my Bird Aeris Mk1 in 2020. In less than a year, I had wear mark on my stantion. It could be bad-ish frame design, it could also be bad shock design, because I talked with few people with the same problem.
I was thinking about finding spherical bearing for the eyelets, but I have to get shock with bigger eyelets like canecreak.
Im not buying fox, because they crack at the top of the damper. Probably wont get another DVO (I returned my shock, and got full refund).
This is a genius takedown of an increasing problem. Frame designs are pushing to have more and more shock performance in smaller and smaller spaces. You should look at the digit bikes design, I think it addresses this.
Slightly bitter Steve is the best Steve 😄
What do you think of the Norco Sight VLT's use of a bracket with bearings to get the trunion shock sideways? Seems like it solves the lateral braking forces problem by having bearings in an X pattern. Not quite as good as spherical bearings but better? My experience has been great. 2,000 hard freeride trail miles on mine with one 50 hour service on the RS Super Deluxe. It actually blows my mind I broke the alloy chainstays but the shock is still going strong.
I had a customer who kept bringing his Bomber CR coil shock to us because it was leaking. After rebuilding it 3 times we sent it to Fox. They had a guy call us and asked me if it came off a kenevo ebike - it did! He said "yeah, we see that yoke design crack the shaft on these all the time." I was left with my jaw on the floor; you can't run certain coil shocks on yoke design bikes because they can't handle the side loads! Whaaaat
Stumpjumper Evo, IYKYK :)
Cough Specialized cough... Heard of a lot of blown dhx2s with the Enduros and the stumpies 🙄
Yeah, I hear the DHX2 doesn’t play with these linkage frame interfaces.
My question is then, are these shocks a waste having been run as such just for a short amount of time?
@@niklasdr I wouldn’t run them at all on the enduro. I’ve heard of people blowing them after one ride
Would love to hear your thoughts on ProPain’s suspension design. No trunnion and no yoke. Ad spherical mounts and it would be a winner…
Judging by my current bike with very similar suspension layout (minus the floating lower mount)it's pretty good in terms of side loading the shock, only issue being *a* *lot* of rotation in the upper eyelet, so eyelet roller bearings highly advised, both for sensitivity and bushing durability.
Overall, pretty good. I like most of what I’ve seen from Propain, not just the shock mounts but the bikes as a whole are nicely done.
Dynamic comments Steve 👍🏻
Good video as always.
I just have an understanding question regarding the side loading issues that can occure with extending yokes that have one eyelet rotated 90 degrees:
How do they create more sideloading torque than a construction without the yoke?
I can get behind the idea that an extending yoke with all pivots oriented in one way (pivoting in the up-down direction) will act as a long lever for side loads. But when using a 90 degree rotated bushing in the middle (where the shock is mounted to the extending yoke) I would assume that the load is the same or even less for a given side deflection on the point where the yoke is mounted to the rear triangle. As the length is bigger the needed angle to compensate the side deflection would be smaller for either end (shock bushing to the frame and yoke bushing to the rear triangle -> The middle one can move freely as it is rotated 90 degrees).
I would appreciate if you could explain that in laymans terms! :)
Exactly my thought also. With such a construction you should get " free" rotation in all directions. In the pich axis you have the upper mount, in the yaw axis you have the lower mount and in the roll axis you have the shocks ability to rotate between the eyelets.
@@mikaeljc76 not really, because it's not about rotation, but about bending forces, with a very long shock (a yoke effectively extends the shock length) it wants to bend on itself, that's part of the issue, add to that frame bending side to side, with both eyelets setup 90° to each other, the shock has to bend on itself, instead of at the mount, hope you understand what I mean.
Here's a brief explanation.
Start with adding a yoke to extend the shock. Then you have 3 rotation points: the front shock eyelet, the rear shock eyelet, and the yoke mounting points. When those three are aligned, they all rotate in the same direction, so if one rotates, the others can as well, taking up movement without loading anything.
Rotate the middle eyelet so it's turned perpendicular to the rest, as is done in the clevis design. When that middle eyelet rotates, the other eyelet and yoke mount no longer rotate with it, because it's direction of rotation is perpendicular to them. That movement has to be taken up somewhere, so it goes into the shock shaft. Bam, side load and increased wear.
I love tuesday tune! How could the shock be isolated from unwanted forces of the frame? Spherical eyelets on both sides?
That’s the ideal way, but sphericals are heavier and more expensive too, so it’s not entirely without trade off.
So what bikes do you recommend that have well designed frames for the shock/suspension?
FWIW as a MechE outside the bike industry, I've been impressed with Pivot's latest vertical shock designs.
@@midMTB Isn't it trunion mounted though?
@@MrSatchelpack Yes, some are; however, the latest Pivot bikes 2019+ seem to be designed & manufactured well. I would prefer a Trail 429 over a more flexible Ripley frame, with a yoke coming from behind the seat tube.
Santa Cruz bikes are some of the sturdiest I've seen in terms of design for the long-term. They're not my style and a bit heavy, but their lower shock-mount is good. The previous design also allowed for both points mentioned here, the upper counter-rotating link is not acting as an extension like in the Ripley.
@@midMTB I think they've vastly improved things but I remember reading somewhere that some of pivot's older frames were incompatible with coils simply because pivot was using the shock as a stress point as a way to reduce frame material/weight, and since coil shocks are less rigid than air shocks due to the smaller stanchion, they were wearing/breaking shocks at absurdly high rates. The newer bikes should be better like you said, but people need to watch out for the older ones.
so im wondering what the difference is between linair and progressive coil springs..all the data is based on a linair spring and not a progressive spring..is there a topic on this issue.
i have the option to go with a 60mm rocker but i like the feel of the 65mm rocker, so is my option a progressive spring to make it ride more on top more mid-stroke support?
Hey I'm more than a little late here, but I'll ask anyway:
In a yoke mount the eye is turned 90 degrees so the axis is vertical - wouldn't this accommodate MORE misalignment, given the additional axis of rotation? Lateral flex from the rear triangle and yoke itself is taken up in the vertical rotational axis, while the "normal" rotation around the horizontal axis is accommodated at the other ends of the yoke?
What could a shock manufacture do to increase the side load capacity of a shock? More overlap internally. Bigger shaft bushing. Stronger shafts.
Hey Steve. Thanks for your videos, always very informative!
I’ve had many DU bushings that were so tight that the axle is completely stuck. Stuck so bad that I need a vice to extract it. This has 3 problems: increase wear in the shock (anodisation inside that is wearing), wear at the frame interface because the axle rotates with respect to the frame, not with respect to the shock! And also the tightening screw that keeps getting lose.
I tried IGUS bushing but couldn’t get the axle in without damaging the material.
In one old frame I was able to install a roller bearing. On another frame it wouldn’t work so I asked a friend to machine a bronze bushing.
Had the problems on 4 separate frames, and with 3 different brands if shocks.
What’s your take on that?
You could pick up a 15mm reamer as it sounds like the hole in the shock is to tight? FWIW, Cane Creek used slightly smaller holes in their shocks with their own hardware and standard 15mm bushings don't work in them. I was able to use a reamer and open it up to 15mm by hand.
DU bushings should be quite tight - they do have significant enough friction that roller/ball bearings are noticeably better, but it can be hard to find a high enough load rating for small bearings like that, plus sealing needle bearings is tricky. The Igus ones are usually pretty good though, sounds like your reducer hardware was not properly chamfered.
I've had a new bike where the bushings were so tight that the shock had wear marks after a few hours of riding (from torsion of the shock due to suspension travel). Warrantied the shock through the bike manufacturer, and installed IGUS bushings on the new one. Shock lasted for years until I replaced it by a different model - for an upgrade, not a failure.
Hey Steve, I was wondering if you came across any spherical bearings that would work with a 12.7 eyelet or plastic fox bushing (and 8mm bolt)? I've got a '22 Process 153 with trunnion mount. Misumi probably wouldn't mind taking a custom order... but at what cost, you know.
I just wish there were some out there like the DT Swiss Spherical bearings (DCWDXXXXN08079S). but those are 16 OD and 10 ID.
EDIT: I drew this up in CAD and using a cane creek kitsuma eyelet (14.7 bushing OD) you could get nominal 1.85mm of plastic bushing material around an 11mm microball w/ 8mm thru hole. Hmmm...
Well , this is a message for YETI, specialized, ibis, pivot, canyon, commencal, etc...
How about a short list of manufacturers who are “doing it right”?
Santa Cruz?
Something you'll see on a lot of bikes is linkages in single sheer which creates uneven loading. If you did this within most engineering industries you'd get laughed out of the office but it seems to be almost standard practice within the bike industry.
I´d say this is primarily due to bikes being very limited in width
want to buy a coil shock for my 21 commencal meta, scared to snap with my weight 115KG. most of the meta TR comes with airshock
My 205x65 trunnion shock failed prematurely by scoring the axle. Can you give me a quality shock recommendation for my Scott salvage?
Comparing to motorbikes - bicycles have no business costing what they currently do. The industry needs a price reset.
I've already seen some Fox X2 Trunion with cracked bodies near the eyelet
Sadly, so have we. It is not isolated to that shock or brand either.
What would happen if we would switch back to pull shocks? Or make the upper shock joint with two degrees of freedom?
Pull shocks are a bit tricky to use with compression springs, but other than that there's no specific reason not to use one.
Sorry did you say Levo/Kenevo? Specialized frames are killing shocks and the big S is just putting it down to the shocks. Good job they're pitching them at the cheap end of the market eh 🙄 but thanks for making this video and hope the industry listens. I've just put a Jade X coil on my Levo SL which is supposed to be beefed up but we'll see if it can handle it and lasts longer than the last coil shock....
Like the 2021 fox x2, looks like it's happening on certain bikes
What, in particular, are you talking about?
Why not start adding spherical bearings to bike shocks? Seems like that should be the first step.
My last 2 specialized bikes blew out their shocks , my stumpjumper in 1 year, my enduro 2 years.
Given that the service intervals are typically 1 year (100hrs), I don't think you can actually blame the frames specifically for that. Seals wear out.
My rear shock is just fine on my hardtail.
As for the bike industry, I believe they will never stop pushing tech in the wrong way just because parts don't break enough to justify a drastic change.
Whats your sag setting on it?
@@yetti423 My back wheel is set at 26 psi.
@@onilovni1234 My sag is set to in a tree, ditch, or over bars :)
Taking an example, is YT’s move to go to a Capra with a linkage-driven shock good or bad?
Will it ease the shock’s bottom mounting hardware from rotational forces? (Assuming the linkage uses bearings)
It does make it easier to change coil spring on the shock as the shock mounting hardware is not in the way and has to be removed and replaced every time.
But does this linkage design at all void use of certain coil shocks such a as the Fox DHX2?
(Ibis Ripmo is to me known to not work well with the DHX2. Does it have a similar linkage-driven shock interface?)
The old design bent the lower hardware and pulling the frame in. So i guess the new design fixes that
@@diamondsink2000 Thanks for the clue. I didn’t know there was a problem. Haven’t heard of it. What problems did it give? Not much rotation there, if at all.
Other frame mounting designs have considerable rotation, for example the 90° rocker links.
Or am I misunderstanding what you mean?
@@diamondsink2000 Ah ok, I misunderstood you there first. I now get you mean the a bit long 40 mm long lower shock hardware bent. I can see that happen, even if I don’t know of it having happened. Thanks for the info.
Would a coil spring shock reduce the shock’s exposure to these problems?
How would it?
Generally speaking no, coil shocks are actually usually worse at handling side loads because the body/shaft interface is less stiff relative to the stiffness of the eyelet.
Can’t you put bearings which are not so rigid in the bearing mounts of the trunnion? Wouldn’t that make the flex go to the bearings ? Might be a dumb question but I’m really curious
Don't think it would help one bit, the spacing is too wide.
@@piciu256 is correct - the spacing is very wide and rigid, and axial preload on the bearings takes up the play.
Is there any way to soften the impact of these sideway forces? E.g. with some sort of special bushings/bearings? My Specialized seems to be affected by it, it has a yoke and regular bushings (no Trunnion mount), and it appears to have eaten my DVO Topaz T3 in around 5 months.
The shock is now losing air, and Im not sure this will fall under the warranty.
Roller bearings help a little, they aren't rigidly held, so the shock can find it's comfortable spot to some extent
Which model
@@robertg4249 A Kenevo. It seems to have a very similar yoke system as the older Specialized Enduros, although a slightly different layout (not the "Specialized X" anymore). The new Enduros seem to have an updated linkage design, where the yoke doesn't extend the shock length anymore, so they could be better in this regard? I don't know.
@@piciu256 Do you have any recommendations? Fox now offers a ball bearing kit for shocks, although it seems to be 8x30mm only, and I'd need something for 8x20mm.
Real World Cycling has needle bearings in 8x19mm, with some additional 0.5mm spacers, so theoretically it would fit. As far as I know needle bearings are not great for axial forces, so not sure if these would actually help? Also the shipping from US to Germany is a whooping $35.
Enduro Bearings themselves, whose bearings are used by RCW, also offer a needle bearing for shocks, however without the spacers, so only in 19mm or 20.85mm, which might or might not fit (and interestingly according to Chris from RWC the development of this product was a breach of an agreement of not offering a competing product). At least this would be available in Europe (once it's back in stock sometime next year).
Are there any other options?
@@sp00n I was talking about needle roller bearings, should have been more specific. They do not take axial forces at all, as in they allow the shock to move side to side, I think they could help a little, plus they are way smoother in frames with high eyelet rotation.
How do dirt bike manufacturers go about their single shock rear suspensions? Dirt bikes might not have water bottles to consider, but they do have engines and transmissions which occupy space. Do they just build everything stronger (thus heavier) because dirt bikes are not pedal powered?
spherical mounted top, yoke mounted to linkage at the bottom. and a massive shaft and with tons of overlap.
Well, there's a few things at play there:
1. dirt bikes are far less concerned with weight - the shocks are very heavy compared to MTB shocks, typically about 3-5x the weight (the MX Tech National shock is renowned for its light weight - usually it's about 7lbs/3.2kg vs MTB shocks ranging from 0.4-1.0kg incl spring) but only having to deal with a vehicle 2-2.5x the weight. As a result, they can do things like use bigger shafts, and make them out of steel instead of aluminium
2. Dirt bike shocks may not be quite as reliable as people often think. Their recommended service intervals are about the same as MTB shocks (actually less in many cases - KTM PDS shocks have a 30hr service interval), and they do often blow if not serviced at the recommended intervals.
Every bike should have a pull shock bro!
🤣 lemme go find you a K2 Razorback...
Don't see how that would fix the side loading issue though 🙃
@@ButterSuspensionAncillotti Scarab for me, please! Thank you! :D
I totally agree with everything said! But there is more... The current trend of extremely low and sloping top tubes (for no logical reason, standover height is not an issue that far back) makes it even harder to fit a decent size shock in the frame. AND it makes the frame less stiff of course. And it's ugly. ;-)
A funny thing is that it's quite often the large frame manufacturers that produce bikes with yokes. Shouldn't they be the ones that have the knowledge? I mean, a small manufacturer might not have engineers and designers with sufficient experience to avoid flawed designs, and that would be easier to excuse.
It's about the looks mostly, a frame that sweeps low looks good imo, plus you get more standover at once, since the tube goes mostly in a straight direction.
Its to fit decent length dropper post
@@lewistaylor1489 nah, aspecially on frames that don't have more depth anyway.
@@piciu256 yeah silly me, a high horizontal top tube straight from the top of the head tube would really enable me to have a 200mm dropper. If i was 7ft tall maybe.
@@lewistaylor1489 first of all we were taking about top tubes, not seat tubes, they are somewhat independent, secondly I'm running a 180mm Oneup post (I could have fitted 190 since the frame has a lot of insert depth) on a frame which many reviewers dubbed as having a "high seat tube" (440mm in Medium)
and I'm only 170cm tall, so no, a low seat tube doesn't necessarily all of for a longer post, it does however allow for up sizing, which I'm not sure is applicable anymore, with most bikes being really long already.
Great example being the newest Commencal Meta, all the low seat tube does is make it so a lot of seatpost is sticking out of the frame, since the tube bends so close that you would be be able to fit a longer dropper than before anyway (assuming the dropper is slammed, which is unrealistic with how low the seat tube ends)
Please don't throw a rock through my windscreen :(
This had to be said!!!
now, you haven't seen RB-bikes IQ with something like 50cm yoke.
Your comparison between the trunion mount and DU bushing side flex was misleading. The bearings on the trunion mount will have side play, similar to what you showed with the Santa Cruz specific shock.
It's probably not as misleading as you are thinking though. Say your pivot can allow 0.001" of misalignment through clearances. With an eyelet, that misalignment happens across ~12mm of width. On a trunnion mount, it happens over 54mm. The angular movement allowed by clearances in the trunion mount is significantly less. The same thing also applies to deflection in the materials, any deflection in the 12mm eyelet will allow significantly more angular deflection then the trunnion.
@@dsm156 I understand, just saying that bolting it in a vice was not a very good representation. Next time I remove my shock it will be interesting to leave the trunion side attached and see how much side-play there is.
@@enkie22 once bolted up, the play in the bearings is taken up and it is very rigid. Check it out if you have a bike with trunnion mount - you can easily compare the trunnion end to the non trunnion end and see which end is more rigid.
Why not put a plain spherical bearing at each end of the shock? Plain spherical bearings avoid side load by design, so this seems to be a durable solution for the side load problem. Plain spherical bearing: en.wikipedia.org/wiki/Spherical_bearing.
A few shocks do (Curnutt back as far as about 1999, Cane Creek from about 2004-2009, Ohlins for a couple of years although unsure if they still do, currently Push and EXT), it's generally a good solution, though there are some tradeoffs with weight, wear (which leads to knocking) and cost. However, for sure it prolongs the life of the shocks.
Can you solve the mystery of why all shock manufacturers will not warranty or approve of a coil on Specialized Kenevo and Levo
Because the forces of the frame will break the damper shaft.
On an air shock there is more meat to handle those forces.
Rear suspension on a bike goes something like "I'll just check how the bearings are, oh look they're all fucked." It's the same problem with those damn chain-wear indicators, when you do go to use them you leave your wallet open on the workbench with your credit card details in perfect view.
do you also sell eggs?
Maybe Steve is into Omlette or on some kind of weird egg-diet?
Why isn't this more common knowledge? I wonder when people will learn that the more they know about their hobby, the less they will ultimately need to spend?
lol if you have been following hambini's bb roasts you know the frame manus dont want to give a crap about tolerances. #closeenoughisgoodenough there is no way they will put in effort for shocks given what they can be bothered to do for bottom brackets...