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Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

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Old 08-16-06, 08:29 AM   #1
dawes99
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Creaking cranks

Hi, please could anyone offer advice on a problem with new shimano cranks that won't stopping creaking . Everytime I tighten them they are sound for a while and then after a good climb the creaking starts. The bottom bracket cassette is sound. The design is a four flats taper and the old cranks were also shimano and did not make any noise or come loose. Could there be a slight change in the manufacture of the taper over the years? Many thanks
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Old 08-16-06, 10:29 AM   #2
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Check that the crank bolts are tight AND that the bolts that hold the chainrings to the crank are tight. You say that the bottom bracket is sound... have you removed it or done anything to it recently?

Basically all square taper cranks ever made have a standard taper EXCEPT for Campagnolo cranks and old Ofmega cranks I believe. So there's no difference between the taper design of old and new Shimano cranks. It is possible, however, for the tapered part of the cranks to become bent and worn, because the cranks are softer aluminum while the bottom bracket spindle is hard steel. Were you running the cranks for a while without tightening them sufficiently? If so, you may have damaged the taper...
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Old 08-16-06, 11:00 AM   #3
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Also, did you lightly apply a thin film of grease on the taper before tightening? It helps the cranks to go onto the taper better. Did you use a torque wrench to tighten? Not sure offhand what torque they take, but it is on Park Tool's website.
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Old 08-16-06, 11:30 AM   #4
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Quote:
Originally Posted by moxfyre
Were you running the cranks for a while without tightening them sufficiently? If so, you may have damaged the taper...
so, would running the cranks without tightening them sufficiently eventually cause catostrophic damage to them (increasing the damage to severe), or simply cause a perpetualy annoying ride? I assume that on a fixed gear this would be more severe than freewheel?
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Old 08-16-06, 11:36 AM   #5
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so, would running the cranks without tightening them sufficiently eventually cause catostrophic damage to them (increasing the damage to severe), or simply cause a perpetualy annoying ride? I assume that on a fixed gear this would be more severe than freewheel?
Dunno about fixed vs. free... I'd guess it's more or less based on how much stress there is on the cranks, so probably a bit more for fixed.

If you ran the cranks like that perpetually, you might eventually round them off so bad that they flopped around and would stay securely on the BB spindle. Kind of like a bolt rounded off by using the wrong size wrench. I wouldn't hazard a guess on how long that would take.

Don't do that Make sure your cranks are sufficiently tightened! If there is play (you can wiggle them around) no matter how much you tighten them, then they are ruined.
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Old 08-16-06, 11:49 AM   #6
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Quote:
Originally Posted by slim_77
so, would running the cranks without tightening them sufficiently eventually cause catostrophic damage to them (increasing the damage to severe), or simply cause a perpetualy annoying ride? I assume that on a fixed gear this would be more severe than freewheel?
I did that for about 4-6months, basically the wiggle and wobble got so bad I took a look and noticed it was totally loose and so I tightened the crank but I kept over tightening the wrong nut and it worked itself loose after 1-2 day ride so I kinda gave up for 4months and after awhile I couldn't get any speed since the wobble was so great it was messing with the chain and the gear. Finally got it right after figuring out which nut need to be perfectly tightened (not too tight or loose) and so far haven't noticed any problems, did noticed some rounding off of the square taper though.
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Old 08-16-06, 12:15 PM   #7
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Quote:
Originally Posted by moxfyre
Dunno about fixed vs. free... I'd guess it's more or less based on how much stress there is on the cranks, so probably a bit more for fixed.

If you ran the cranks like that perpetually, you might eventually round them off so bad that they flopped around and would stay securely on the BB spindle. Kind of like a bolt rounded off by using the wrong size wrench. I wouldn't hazard a guess on how long that would take.

Don't do that Make sure your cranks are sufficiently tightened! If there is play (you can wiggle them around) no matter how much you tighten them, then they are ruined.
Right , thanks guys.
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Old 08-16-06, 12:52 PM   #8
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PS: I was using adjustable wrench and a pipe wrench, it really was frustrating not working with the correct tools. So by all means get some correct tools.
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