Shimano MTB Crank Failure || Don't Let This Happen To You!
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- čas přidán 10. 09. 2024
- A short video showing a potential defect with Shimano 12-speed mountain bike cranks. At the end of the day, make sure your cranks are installed properly or have them inspected, this seems to be a more widespread problem that I initially thought.
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The key is to tension the bolts evenly, tighten a little one one side then the other. Keep alternating bolt tightening until both are up to the correct torque. I know you said this, but this is the most crucial step.
For SRAM DUB cranks, tie a strap between the crank and the chainstay. The cranks come off everytime. Learned that trick from the bike shop.
That's a good one. I like to use a step stool to get mine off. I have another video showing how I do it. Works well for me!
I set the pre load finger tight, 15nm for the pinch bolts, never had an issue with SLX cranks.
I can see people with 6100/7100 series trying to run 55mm chain line just by adding spacers when they should be using 6120/7120 with longer spindle
This is definitely user error.
XTR cranks use a different way of installation. It is similar to SRAM’s DUB crank install with self extract bolt. However I found it not as good as SRAM.
Ah didn't know that! I definitely prefer the SRAM system, although it can be hard to remove.
They don’t if the mechanic has got skills to read Shimano user manual. It’s written on den crank: 12-14Nm …(for e.g.)
Don’t lookin left and right crossing a street is also dangerous. Not tighten bolts correctly also.
I agree, but most people buy bikes from a bike shop or direct from the factory assuming everything has been installed correctly.
Your theory about tightening one cinch bolt all the way then doing the other sounds plausible. Another issue could be people tightening the cinch bolts on the crank arm (correctly or incorrectly) before tightening the crank bolt that holds the arm on. This would put the spline interface off a bit and encourage loosening. I build all my own bikes and have used this style Shimano crank since maybe 2007?? and have never had an issue.
I think this is the most plausible one because Shimano has been using this design forever and it seems to happen more on certain frames, so there is a chance that those specific factories are installing them incorrectly.
The cinch bolt before the pre-load theory you mentioned makes a lot of sense to me, as some people might think that the pre-load bolt is just a dust cap or something.
I've run the same style Shimano cranks on other bikes with no issue, but it does seem like either certain cranks or cranks installed by certain companies seem to have a higher prevalence of this problem.
Thanks for commenting!
After watching I went and checked my Salsa and they were both loose. Glad I came across your video and probably need to go over the entire bike more often than I do.
You should check your bolts
You should indeed
Fc-8100 cranks have only 11mm of spline. Fc-m8000 and older. Hollowtech II have 16mm. Engineering error, not operator.
I did not know this. I wonder why they reduced it so drastically.
Cranks are fine, super robust, just tighten them properly.
12 to 14 nm sounds about right. Dead simple to install though. And use a torque wrench to ensure the bolts are tight enough. It’s quite possible that the initial assembly at the factory was done wrong. A good shop build should check all these things. I think also that many people over tighten the preload and prematurely wear out the bearings. Same with SRAM or Race Face style of preload collar. Those things should be called play adjusters because I think people believe those devices need to be tighter than they need to be.
It happens to me also, I realized Ididn't torqued the bolts in an alternate way. Anyways, I check the bolts from time to time.
Grease on your bolt threads is critical for achieving proper torque. Not against lock tight though.
I have replaced the preload nut with a aluminum one instead of the default plastic.
I have been using it for 2 years it mine came from china.
Been riding Shimano parts for 30 years. Never had an arm fall off but ive had them crack in half a few times. I still prefer them over anything else.
I have had this happen on my old bike whithin the first quater of ownership. I got the bike, the bike was to service 1 month after I bought it at the shop, to get a bolt check etc. and then whithin 2 months the crank arm fell off. Luckily while i was climbing.
An entire video on user error.
Not everyone works on their own bikes - many people assume that their bike shop or the factory they bought it from installed everything correctly, but that isn't always the case as evidenced by the number of people mentioning that this has happened to them. The only two people who touched my crank before it fell off the first time on my bike were whoever installed it at the factory and whoever built it at the bike shop I bought it from. The end user is always ultimately responsible for keeping up with maintenance, but a crank falling off less than 7 months after the bike was purchased is not user error.
Regardless of who the user is, a crank falling off mid-ride is almost certainly going to cause a crash.
@UmunhumCycleworks I put my bike together and I don't know how to put bikes together. I hadn't riden in years so I ordered an Ibis Ripley a couple years ago. The bike came partially put together. I did my best, but I better check over things. Good vid.
I just replaced my safety tab on my Polygon Xtrada.... cuz, my left crank fell off too. I think the fixing spacer also, is slightly stripped. The crank arm is fragile for the it's purpose.
Yeah, loc-tite, not grease! It could be the plastic pre-load screw as well. I would loc-tite the new one.
14 nm evenly tightened and hope.
Even thoe old 10 hollowtechs do the same thing.
Chech every ride or two for proper torque.
A paint marker on the bolts would not be a bad idea to see if they have loosened.
@@UmunhumCycleworks I agree
Seems like fake news because mtbers don’t pedal.
😂
happened to me 3 times
Loctite the crank 2 bolt
Blablabla 11 minutes blablabla put loctite on you bolts blablabla 11 minutes blablablabla ..... it was a content ...
as soon as you have ridden these cranks loose once you absolutely need to replace it because once the splines wear it'll come loose alot more. best solution is to just not run shimano cranks.
Shimano's HTII crank interface is arguably the best engineered interface out there. This is why so many other companies (FSA, Samox, etc.) copy it. But somehow, somewhere, there's always THAT GUY who manages to screw it up, usually by reefing down on the NDS preload end cap, or what we see here. No, the best solution isn't to not run Shimano cranks. The best solution is to just ride your bike and leave the assembling and fixing to people who have a clue.
@@jcvd1826 I’ve had multiple sets of shimano cranks come loose only the one set I fitted didn’t come loose for the exact reason that I over torqued them. They suck it’s not really up for debate. You crying about fitting them wrong isn’t going to change any minds. Every non shimano standard I have run have never come loose on me so I’ll continue to use my Hope cranks that don’t come loose.
@@torturedtyresdepartment34 years on Shimano cranks with 0 problems. Maybe your bike shop sucks.
@@johndef5075 there’s always people who never have issues with known faulty or poorly designed/engineered parts. Doesn’t change the thousands of people with correctly fitted shitmano cranks that have come loose on them. They aren’t fit for anything past gravel riding.
Over 30 years running Shimano cranks and never a problem. My mom raced for years and never had problems with Xtr I always ran xt and never had problems. I have slx now on a Ripley without problems. Hope I don't have problems later on.