Bicycle Mechanics - Creaky cranks
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06-14-06, 02:32 PM
My cranks on my fixed gear creak. I can't get the chainring bolts any tighter, but they still spin when I take an allen key to them (without the chainring bolt tool in the back). I just regreased and tightened the bb threads, and reinstalled the crank on the taper. It happens when mashing, it happens less when spinning, and it happens both when I concentrate on upstrokes and when I concentrate on downstrokes. It happens out of the saddle as well. Am I correct in thinking its the chainring bolts? Would replacing them make a difference? Could it just be a sucky crank and chainring? (Stronglight Track)
06-14-06, 05:12 PM
I've found that bottom bracket creaking usually comes from crank bolts not being tight enough. Since you've just reinstalled the cranks, make sure the bolts are tightened. With tapered bb axle, you need to retighten the bolts a couple of times in the first 100 km.
If that doesn't do it, try overhauling the headset. The creaking might be coming from there. A good test is riding the bike no-hands. If it's unstable (feels like it wants to fall), you've probably got rust in the lower hs bearings. You can't tell just by lifting the front and swinging the bars back and forth.
I ride a fixed gear year-round and addressed the same problem as above.
06-14-06, 10:51 PM
Lube the inside of the bb cup and the threads. It's more than likely from the bb cup rubbing against the bb. I hope you understand what I mean.
06-14-06, 11:52 PM
When a square taper has been ridden loose, most of the time there is a wear or deformation inside the arm socket. This deformation appears as additional "edges" in between the four sides that are supposed to be there. When these edges get too pronounced, you will not be able to 'overtighten' it past to remove the creaking since it relies on full contact to seat propperly.
When you do crank work ALWAYS have a torque metering wrench. Typical square cranks are 35-45 ft lbs(I usually do 40 or so). The 35 dollar tool (it doesnt have to be fancy) will save you a fortune in damaged crankarms. No matter how many times you think you have it tight, you can never be sure unless you use a standard to check. Since using one, I have not lost a crank to undertighening, and one has never come loose. At all.
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