Salvage cranks with damaged splines

[freeflow]

I was merrily cycling along the other day when the right hand crank of my Pinion drivetrain came off. Since then the cranks have been prone to creaking which is most likely due to fretting and other damage to the splines in the crank. I have a new pair of cranks on order but they will take a few weeks to arrive.

In the meantime, any suggestions as to how to minimise the creaking. Pinions manual recommends carbon assembly paste at the crank is used which hasn't really helped. Neither has liberal applicaation of ptfe grease. Or should I just tighten the cranks bolts to silly torque. The recommended toque for the M5 bolts is 10 nm.

The cranks only creak when applying some pressure to the pedals, such as when cycling up hills.

Or is it just earplug?

[rjb]

I've recovered a worn square taper crank by wrapping several turns of cooking foil around the axle before reinstallng the crank.

[colin54]

Rohloff silencing grease ?
https://www.sjscycles.co.uk/lubricants/ ... kets-8517/
No personal experience.

[Brucey]

your cranks can be stopped from creaking if a little adhesive is used. This will, of course, also have an effect on how easily the cranks come off again too. It is probably best if you only use the high-strength stuff if you have to. Some cranksets used the first version of the HT1 spline when perhaps they should not have; One of my friends happily used such an XTR crankset for some years, and it was only loctite red that was making it go at all.

[freeflow]

I have some 221 loctite or do I need something stronger.

[freeflow]

New cranks fitted but the creak is still present.

Loctite 222 didn't work with old cranks
Carbon assembly paste didn't work with old cranks
PTFE grease didn't work with old cranks.

The crank Axle interface is like (but not the same as) octalink/Hollowtech 2

With the new cranks (using the assembly paste/grease preapplied to the cranks by Pinion) I've tried

Different pedals
Different seatpost/saddle combinations

I have some high pressure moly grease on order which I'll try next.
They to try the ptfe tape/alu foil suggestions.
if the creak is still there then I'll remove the gearbox and clean up/regrease the attachment points

In the meantime I'll be doing frame inspection/ cleaning /regreasing the inside of the seatpost tube.



The ultimate solution is to send the gearbox back to Pinion for an early service and ask them to replace the crank axle.

In the meantime, any other suggestions would be welcome.

[alexnharvey]

your cranks can be stopped from creaking if a little adhesive is used. This will, of course, also have an effect on how easily the cranks come off again too. It is probably best if you only use the high-strength stuff if you have to. Some cranksets used the first version of the HT1 spline when perhaps they should not have; One of my friends happily used such an XTR crankset for some years, and it was only loctite red that was making it go at all.

Further to Brucey's adhesive suggestion, I would carefully apply a thin layer of car body wax to the crank faces, then add metal thickened epoxy (e.g. JB-weld) to the old crank spline area, fit and tighten. Hopefully this should resolve the creak and the wax will act a mould release allowing you to get the crank off if you ever need to. If it resolves the creak I would leave it in place and not try and remove it to check if you can!

If it works you can give up hunting for other possible creak sources.

[Cyclothesist]

Are you sure it's the cranks that are creaking?
There are other potential sources including cleats in their clamps, your cycle shoes, your saddle, stem, bars and more. See this site for further suggestions:
https://www.jimlangley.net/wrench/keepitquiet.html

Bicycle frames are excellent at transmitting sounds to locations far from the source. Their favourite trick is to make every sound appear to come from around the bottom bracket area.

[freeflow]

Are you sure it's the cranks that are creaking?

Well it started after the crank came off whilst cycling, as stated in my original post. As a cyclist for the past 50+ ish years I'm also aware of the indeterminacy issue for creaks on bicycles, which is why I've been swapping things out as in my post a few posts ago.

[Cyclothesist]

Are you sure it's the cranks that are creaking?

Well it started after the crank came off whilst cycling, as stated in my original post. As a cyclist for the past 50+ ish years I'm also aware of the indeterminacy issue for creaks on bicycles, which is why I've been swapping things out as in my post a few posts ago.

Yeah, it can be a frustrating job chasing the cause of a noisy bike. Good luck!

[Brucey]

....New cranks fitted but the creak is still present.

I am rather suspicious of the bolts that attach the gearbox to the bike. I think these might be a bit like chainring bolts in that if there is a small amount of black crud in the joint, it can still creak, no matter how tightly the bolt is done up. Careful use of a mechanic's stethoscope might help to pin down the source of the noise.

[freeflow]

Hopefully the problem is solved. This morning I removed the new cranks cleaned up the interfaces and applied SBX2 grease.

Having replaced and tightened up the cranks I noticed a small bolt lying on the floor. This prompted me to check the tightness of the bolts for the rack and rear hub mounts. I was very surprised to find that the two bolts fixing the right hand hub mounts had come loose, and that the left hand side bolts could also take a quarter turn. On the right hand side the rearmost bolt was almost a quarter inch undone.

Given that these bolts were tightened with extreme vengeance the last time I adjusted the spacing for new chains I am very surprised the looseness I found.

A short 100m tootle did not reveal any creaking after tightening the bolts so Its time for a longer ride this pm. Fingers crossed.

[Cyclothesist]

Sounds good! But where did the bolt on the floor come from?

[Brucey]

I'll wager that those bolts have the 'standard' metric coarse thread pitch, rather than a more cycle-friendly 24tpi or 26tpi; nothing wrong with that per se, but there is very little doubt that for same tightening torque on a coarser pitch, there will usually be less tension in the fastener. In this case it is very likely that the joint settled too; these bolts, being very short, don't have very much 'stretch' in them so they will tend to 'let go' in the event of settlement, unless steps are taken. It is for just these circumstances that the Belleville washer was developed; by using one of these correctly, a short bolt can be given a similar 'stretch' (and resistance to joint settlement) as much longer bolts. Probably your bike was designed by some kind of numptie that didn't know this, or perhaps even care.

[freeflow]

Thanks for the recommendation Brucey. Funnily enough I just bought a pack of Schnorr washers for the crank bolts. Amazon order on its way.

Cyclothesist, the bolt I found was an ex crank bolt that went awol when I dropped it after removing it from the cranks a couple of days ago Unfortunately, the parking area in my rear garden is very aged tarmac (i.e. loose gravel) so anything small like that that gets dropped is a pig to find again straight after dropping, but is in plainly in view a couple of days later when you are not specifically looking for such an item