clunky crank uphills..

A

anferne85

Banned
Hey there..

I am using a deore xt crank m770, with a m770 shaimano bottom bracket.

when going up hill or pedaling hard underload the crank makes a ticking, clunking noise on each revolution. Does anyone know what this might be im hoping i can replace the bottom bracket and it might go away. could it be more than just the bottom bracket? the bike has had a hard life...
 
Make sure the crank arm is not hitting the cable end from the front derailler.

Happened to me once and was driving me crazy till I looked and found it.
 
Do you actually mean that you are getting the clunking every half revolution? I have had this several times on bikes but always just replaced the BB. I've just recently bought the BB tool to remove it and give it a good service as this apparently helps a lot. We shall see I suppose. It might be worth giving it a go. Or if you couldn't be F'd just go ahead and spend the money on a new BB.
 
i went hrough a few sets of bb's and crank arms with a similar noise, the left crank arm actually rounded the shafts corners and could slip (if you have a square lock one you might wnat to check that out)
 
castlo said:
i went hrough a few sets of bb's and crank arms with a similar noise, the left crank arm actually rounded the shafts corners and could slip (if you have a square lock one you might wnat to check that out)
Click to expand...

Hollowtech cranksets are a little different......no squared axles or anything.

c32-4.jpg


To the OP, the bottom bracket probably needs to be greased up. Also, tighten the chainring bolts.
 
Could be anything. We need to know what bike it is.
My seat was the cause of those sort of noises last ride.
Is it a GT? The iDrive will do it (no it is not an Apple product).
 
anferne85 said:
Hey there..

I am using a deore xt crank m770, with a m770 shaimano bottom bracket.

when going up hill or pedaling hard underload the crank makes a ticking, clunking noise on each revolution. Does anyone know what this might be im hoping i can replace the bottom bracket and it might go away. could it be more than just the bottom bracket? the bike has had a hard life...
Click to expand...

If you bought a Giant with better spec u would not have these worries!
 
indica said:
Could be anything. We need to know what bike it is.
My seat was the cause of those sort of noises last ride.
Click to expand...
Bingo, lots of potential causes, pedals are another pretty common one, slightly loose bearings can cause them to knock around the top of the stroke.
 
Yer it would be bottom bracket or pedals for sure, Pull them all apart clean with petrol grease seal and put back in should fix it unless the bearings have a mountain of play in them like mine do. Im just to lazy / cheap to buy a new bb.
 
Take note of, if the noise only happens on the down stroke of the left crank and if so take the left crank arm off and check to see if the outside of the bottom bracket bearing case has any marks from hitting the inside of the left crank. This is caused by to much preload on the bottom bracket bearing and will make a ticking sound as the left side goes down especially under load, like when climbing. If this is the case the plastic preload screw is only supposed to be 1.5 nm which is 2 finger tight and is often over tightened.
 
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