slightly grindy crank

[Hackfall]

Hi

I wonder if anyone can advise what this might be. I have 105 Octalink BB (5500) with Dura Ace Octalink chainset (7700), recently put together, done about 2000 miles on them. Just now when the cranks are under pressure pushing hard lets say out of saddle in a high gear over a rise or a steep hill where out of saddle effort needed. I notice now a sensation and sound from the direction of the left crank. It's a sound that sounds like metal rubbing to metal and whatever it is I guess is due to the flex and pressure on the left crank, but whether this is the axle or the crank connection to the BB its very hard to tell. I am not sure if this is enough for anyone to give me pointers on where to start or if you would need me to try some things out and report back, its a new one for me. Thanks.

[Brucey]

is it the front mech rubbing by any chance?

cheers

[Hackfall]

no, pretty sure not as it happens in any gear not just those where the chain is very near the front mech. Pretty sure I checked that by glancing down at the time, and it sounds different to that too, a lower pitch than a front mech rub. Have found something from googling about tighting the crank bolt which i'll look at too. Some steep hills tomorrow morning so maybe an opportunity to diagnose more.

[Brucey]

Do double-check that both parts are the same version, V1 or V2.

IME if the crank is actually worn loose on the spline with an octalink, no amount of tightening will sort it out. If you are lucky the joint is still good but was simply assembled dry and is now creaky; IIRC shimano suggest that you grease the interface before assembly.

If the spline is now worn to a light push fit then sometimes a 'cure' can be had by cleaning everything and using Loctite on the joint instead.

Don't forget that the only time the right joint takes any torque load is when you are on the left pedal, too, so don't automatically assume it is the LH joint making the noise.

Another thing that might be making the noise is a dry pedal thread; disassemble, regrease, and reassemble.

cheers

[Hackfall]

thanks brucey all definitely the same version. As I recall the splines (if thats the right term) were already greased, I did not add any myself. funnily enough I never heard a thing on Sunday and then went for a half hour lunch ride today and its been creaking every pedal stroke. If I unclip from the left pedal no sound, and unclip the right its loud and clear. So I guess I will start with the pedal and bb connection to crank regreasing first. There's no play in the cranks, solid.

[Hackfall]

An update. I took the left crank and pedal off and cleaned up and regreased, reassembled. Took it out today and generally a lot better but again out of saddle especially when rocking and rolling on steep (25%) small section I was getting creaks on every pedal stroke, much much quieter now though. I am replacing my pedals anyway which was well over due, I have had the same Look Deltas on for years, and they squeak a bit too, so once they are taken out of the equation if this persists I will take the right hand side of the chainset off and re-grease here also.

[Brucey]

ah look pedals.... definitely need to 'look' at those carefully... squeaks and creaks were one of the things that caused me to give up on those about 25 years ago.

If you spray thin lube onto the pedal mechanism, the cleat, and where the cleat bears against the pedal, and the creak goes away (normally temporarily) then you have your culprit.

cheers

[Hackfall]

thanks well here's hoping its as simple as that. I have some Keo Classics on their way to me. I do like look pedals and held off changing as I only had one pair of cycling shoes so have kept the system pedal system on summer and winter bike. Now I have summer and winter shoes I can switcheroo more easily, though I think new pedals for the winter bike will be on the Christmas list too. Will report back again in a few days.

[Hackfall]

an update. I have some new bright red Look Keo Classic pedals, blinged up my bright red 631 steelie no end and silent from squeaks yay. But....

Still what sounds like creaky left crank, only under pressure, out of saddle on steeper climbs. Better than it was after regreasing where there crank arm connects to the BB. I have not done the drive side yet, might be worth a try. I have read that Octalinks creak anyway and you are kind of stuck with it. If its not a problem then ok but I wonder how you then tell when there really is a problem and the BB is knackered, which this should not be, its not done many miles yet.

[Brucey]

if it really is the BB (don't forget to check the chainring bolts again...!) then there are several distinct places where a creak can occur;

-where the cranks bolt to the BB spindle
- where the BB touches the frame
-where the sealed unit fits into LH cup (most versions have an integral RH cup)

if these parts no longer have a snug fit you can clean them and refit with Loctite; this will cause trouble when they finally come apart but this isn't usually intractable and besides which next time they may be coming off for good.

cheers

[albal1]

Interesting reading, as i have a similar problem. I run a GXP Sram BB, brand new, on Look pedals. What i am puzzled by it was fine before i did a full service on the bike.Ouch!

[pedalpower2]

Another possibility folks is the bottom bracket, that could be moving slightly in the frame.
pedalpower2