Non-driveside crank falling off (not running enough thread to lock)-Question
Abit of a waffle:
Ok, my Saint cranks are only two years old. Cosmetically they are battered but structurally great. I’ve been running a Superstar chain guide in addition to two spacers on the driveside which has left (admittably **** stupid..) a gap that only allowed a small part of the crank end cap thread to enable grip/preload.
Ergo- the end cap worked itself loose and fell off during my ride- crank arm wiggled abit BUT I was able to descend and pedal without the pedal rotating against the pedals thread.
My thinking is – if there is enough spline(?) left on the inside of the non-driveside pedal and on the axle then I should be ok to refit a new end cap AND fit the cranks on properly this time?
Has anyone experienced a non-driveside cranks working itself loose like this? What was the outcome? Could you save/reuse the cranks?
My thinking is If I lock it up tight/properly (bought a narrow wide ring) I should ‘save’ my cranks for longer?
Posted 3 years agowwaswasSubscriber
My experience with anything splined is that once they’re worn/damaged they come loose whatever you do.
Having said that the end cap is only there to preload the bearings it’s the bolts in the crank arm that hold it on (think headset top cap and stem – it’s the stem bolts that stop the headset coming loose once you’ve finished fitting it) – so I’m surprised the crank arm came off if the bolts were still tight.Posted 3 years agobuck53Subscriber
I’ve had this recently on Deore cranks on the commuter I built up.
It’s fine now, I removed a spacer from the drive side to show a bit more crank, cleaned everything to make sure it was all pushing up correctly and paid a lot of attention to correct tightness of preload cap and crank arm bolts.
As long as you didn’t put too much force through the cranks and do a proper job it should be fine, I’d have thought.
EDIT: Pics didn’t come up for me the first time I posted. Those look a bit far gone imo, don’t think you’ll stop them working loose, but you might be able to mitigate it to a certain extent with proper setup.Posted 3 years agosillyoldmanSubscriber
1st thing to do is correct the spacer set up on your BB. If a 68mm shell, then 1 spacer on either side plus your chain guide on drive side, or if 73mm then only the chain guide used as spacer.
That’ll cure your spline overlap issue, and correct your chain line too.
The reduced spline overlap may have contributed to the crank working loose, but generally this is caused by the pinch bolts not being evenly torqued.
Get a new preload cap, and a torque wrench, sooty out your shonky BB spacing, and it should be fine.
Edit – just read how fooked your splines are. Add a non-drive arm to the above shopping list and follow the same instructions….Posted 3 years agotops 5Member
I had 2 SLX cranks fail like this – it was terminal. Had something similar with XTs (dont think I tightened them up enough) and they have been fine.
I was wondering whether to replace the plastic pre-load spacer with an alloy one and loctite it in place. I know its not designed to hold them on but may prevent the initial movement.
I believe there is a coke can bodge alsoPosted 3 years agofozzybearMember
We followed a guy down the final decent at Blade.
He had XT cranks with the same issue (and he lost a bolt too somehow!)
He was bloody lucky he didn’t come a cropper, he dropped the crank arm mid roll of on a stone drop and just saved it.
Had it been 2 seconds later he would have been in A&E.Posted 3 years ago
Fozzy I was riding down screaming mile here in the Peaks at a fair pace and I thought the pins on my left pedal must be time to be replaced/renewed…didn’t realise that the crank was showing 1 inch of axle…
On the final cheeky and steep descent I had to kink my left foot ‘in’ to ensure the crank stayed on. just pedalling along wound it off.
I reckon if it had come off on screaming mile I’d have gone straight down onto the bars/to the left and a broken arm/leg etc. Still. It didn’t happen 😀Posted 3 years ago
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