Crank bolts

[montage]

Crank fell off on a ride today...the crank bolt sheared in the process...anyway, if I order http://www.wiggle.co.uk/fsa-v-drive-lh-crank-bolt/ will these fit with my shimano UN54 bottom bracket?

I think these are called ISIS bolts? No idea of compatibility.....but the price is definately preferable for these ones!

Cheers

 

[montage]

if that bolt won't fit the UN54 BB then does anybody have any idea of what bolt will?

Cheers

 

[airbrake]

You need the Shimano bolts with 8mm thread suitable for a square taper BB. They usually have a hex (allen key fitting), but can sometimes be found with a 14mm head size.

http://www.sjscycles...-each-prod3455/

It's possible you now have a damaged thead on your BB axle - and very likely the taper on the crank arm has been damaged also. A damaged taper will mean that the crank arm will quickly become loose again. If by some chance you have steel cranks (unlikely perhaps - but they are out there), they are virtually indestructible.

When reassembling, don't use any lubricant on the taper. The bolt must be tightened securely, and recheck after a short ride. Tightening torque of 28 to 32 pound - feet should be sufficient when all components and taper surfaces are in good condition.

 

[montage]

thanks airbrake, a very helpful response. There doesn't seem to be much damage so I should be ok...I inspected the thread of the BB and all appeared fine, so fingers crossed!

 

[airbrake]

Just to add that although clean, dry tapers are necessary for a stable connection, it's a good idea to apply a little grease to the bolt threads. Hope it goes together ok !

 

[montage]

Cheers again. I'm just having a look at chain reaction cycles' webpage to see if they have any 8mm bolts available as I already have an account with them..... doesn't seem to be the case!...and they are all self extracting which looks like a lot of unwanted faff!

 

[MartinC]

Self-extracting ones are a good idea. They save using a crak extractor tool for removal. Especially useful if you're touring.

 

[andy_wrx]

When reassembling, don't use any lubricant on the taper.

Hmm, this is a bit like the Campag - Shimano debate, with people at both extremes and no agreement

http://www.sheldonbr...ing-cranks.html

 

[airbrake]

I've tried it both ways and seen what happens... I'll be sticking to my side of the fence

 

[montage]

sorted out for free by Edge cycles in Lancaster so a huge shout out to them

 

[PpPete]

result !


airbrake - as a matter of interest what went bad when you greased your tapers ? I've always followed Jobst Brandt's advice on Sheldon's site, but never had a problem.

 

[airbrake]

PpPete, I greased the left crank of a Raleigh that I was using regularly. The crank had been removed and refitted a couple of times previously (both times dry) and the 3rd time I decided to try greasing.

The crank moved further along the taper - in fact the nut (this was an old style BB spindle) reached the end of the spindle taper ! This meant I had to fit a washer underneath to allow further tightening. Admittedly, this crank had seen a fair bit of service - but the change in position was markedly different to when the crank had been fitted dry.

I'm going back to the mid '90s when I did this - and at that time I had no idea of the 'to grease or not to grease' debate. My motivation to grease was to prevent corrosion (I had converted this road bike into a hybrid off-roader, and it got regularly caked in mud etc).

I decided to never grease tapers again - in fact I felt a bit stupid for doing so. Of course, aluminium cranks do settle a little further down the taper each time they are refitted - but this was more than just 'a little'. Maybe I was just unlucky and after all, these parts were far from high quality, but I decided to do things 'conventionally' thereafter. I subsequently found that Shimano and Campagnolo both recommend dry tapers

I do apply a little grease to the back of the cranks after they have been fitted to prevent water entering the taper.

 

[e-rider]

Just to add that although clean, dry tapers are necessary for a stable connection, it's a good idea to apply a little grease to the bolt threads. Hope it goes together ok !

there are a huge number of people out there that don't agree with fitting them dry (although I have to confess that I still do it - but I mainly use HTII now anyway). The best technical advice out there would appear to suggest that this is the wrong way to do it, and it's a bit of an old school habit that doesn't die-off.

 

[02GF74]

one source of creaks is meant to be cured by applying a tiny amount of grease to the taper - I always to, not had problems doing that.

with the loose crank, depending on how much cycling was done when it was loose, you may get away with bolting it up a bit tighter than it was.

I had this happen on the way to mt teide (canary island) and had no means to do it up 'til I got to the hotel (I used to remove cranks for putting bike on plane but since then leave them on) - fixed by applying araldite to the crank and bolt. bolt has small red paint dot, although almost any other colour will work just as well, to indicate if the bolt is undoing - it never has done, be interesting what happens when the crank needs to be removed.

 

[montage]

Not got any grease with me at uni...so cranks will be going on dry! That's that debate sorted