My BB is in need of servicing so it may be related, however every now and then the drivesdie crank loosens off. The crank bolt itslef is tight enough, its actually the top cap that needs tightening (the one with the 10mm allen bolt).

Has anyone else experienced this? I assume its BB bearings responsible but wondered if this was common and whether I need to fork out £6 on a new bolt

its a common thing – iirc the correct torque is **** high

Cheers, strange because ‘flippin tight’ was always ok. I assume a slight lack of the correct levle of torque and wobbly BB is the issue. Its never been a problem before.

RR – Do you have Deus Cranks? Do they look pants when the anodizing wears off? Was thinking of going silver but they’re more expensive.

If you were buying new would you stick with RF or go for Shimano? The thing that puts me off Shimano is I’m not very good at adjusting the star nut, I guess I ought to buy a torque wrench

Try a bit of loctite.

also, do it up with the crank arm off the bike otherwise it’ll tend to ‘bottom out’ on the axle rather than on the stop inside the arm and then keep loosening off.

Next time it loosens and i have time, the whole lot is coming off and I’ll service the BB and loctite the crank bolt.

I’ll provide an update to you all as I’m sure you’re all on the edge of your seats 😀

They work on an interference fit between the splines on the bb spindle and crank arm.The crank bolt only pulls the assembly together and should’nt affect the integrity of the fit.Being aluminium (and soft at that) over time the crank arm splines become enlarged/worn and the cranks arm continually works itself loose.Its usually the cheaper cast Rf cranks which go but truvative cranks suffer the same problem.Loctiting the bolt is a temporary fix,as is applying bearing fit to the splines.Ultimately they will need replacing.

Bah – Had the same issue with Shimano. Is it time to invest in Middleburns?

Had some evolves – they were fine if done up to the correct torque – which is phenomenally high. Silver is always better fro cranks imo. Their should be a “hard stop” on RF cranks tho??

Shimano are better to fit and adjust – follow the hope video principle and do the star nut up and back off 1/4 turn so the cranks spin freely.

http://www.singletrackworld.com/forum/topic/fs-lx-ht2-crank-arms

nowt to lose

I’ve never had this happen on my Evolve cranks. Surely the 10mm one is only fir removal purposes, it’s the 8mm one that secures the cranks?

Steve_b77

Thats exactly whats confusing me.

Next time it happens, if I don’t have time to strip the BB and all that gubbins I’ll remove the crank-arm and re-install.

I think the 10mm one is what the axle actually butts up against (although I can’t remember how or even if this is true)?

I had mine come loose (top-tip read the instructions)and the crank arm was flapping about until I tightened it, though.

I’ve subsequently read the instuctions, refitted everything and it’s been, fingers crossed, fine.

are you missing the elastomer behind the crank arm per chnace?

Can’t see but I’ll bear that in mind.

And just to add, when the crank is loose, the 8mm crank bolt will not tighten up at all, but the 10mm cap bolt is loose.

The 8mm tightens the crank onto the spindle and against the splines.
The 10mm is there for the 8mm to push against when you take the crank off (like the old self-extracting crank bolts) and does nothing when the crank is on, you could take it off if you wanted to. When the crank is on there is nothing to tension the 10mm bolt, only the friction of the threads (unless you tighten it up against the 8mm to put some tension in it). The 10mm plays no part in keeping the crank on or under tension.

I have some Deus cranks that had a bit of a wobble. On close inspection the axle was a bit too long and emerged a hair’s breadth past the splines on the crank, so no amount of tightening would help.

I ground a couple of mm off the axle and it’s fine now.

big john did you have the elastomer (s) on that racing ralph mentions? I have a black plastic disc behind the crank, and an orange elastomer on the none-drive side IIRC.

yes – my failure was to not read the instructions and I didn’t include not only the elastomers behind both cranks but also the 2 1mm rubber washers that go on to adjust the chainline. It was fine with those fitted 😳

perils of a 2nd hand purchase.