chiproth99

I suspect I will need to replace the crankset and bottom bracket, but I'm looking for a less expensive option.

The free crank arm backs off the spindle of the bottom bracket. The result being that the crank and pedal would fall off, if I let it.

I retighten everything and am good for 5 miles before the crank starts to work itself loose.

Loc-tite on the crank screw has not worked.

Suggestions appreciated.

Thanks

Chip Roth

Dan Burkhart 

If this is a square taper crank, and it was run loose for any time at all, it's highly likely that the square hole in the crank arm is distorted and will never stay tight. The crank spindle is probably OK as it is hardened steel. A new crank arm is the solution.

Eggman84

More information is needed. Manufacture and model of bike and of crankset. What is the crank/BB interface? Is the crankarm or spindle visibly worn? How many miles on the bike, is it getting worse, did it just happen suddenly and since then every 5 miles?

dabac

Usually, once a crank arm starts to wiggle, it quickly destroys the fit between BB axle and arm. Getting it to stay on after that often turns out impossible. As luck would have it, manufacturers have realized this and it’s often possible to purchase only the left arm.
The BB axle - being steel - will usually not be damaged.

andrewclaus

If there's a bike co-op near you, they'll have a bin full of crank arms, maybe even sorted by length, for a few bucks each.

dsbrantjr

Good advice. The crank arm does not need to match exactly, just the length (should be stamped on the inside of the arm, likely 170mm+/-) and orientation of the taper, "square" or "diamond." Might get a used or takeoff one cheap at a bike shop. Don't forget to torque the attaching bolt/nut sufficiently, and the pedal too, so they don't come loose again.,

Miele Man

I've managed to get quite a few extra miles/kilometres from a worn square taper crankarm by using a gel cyanoacrylic glue to glue a shim to each of the flats on the bottom bracket spindle. That works until I can find the matching crankarm.

Cheers

veganbikes

Just for those stumbling in the thread was started on 10/25/2020 at 11:50am and the final post was that same day at 1:47pm. Not saying that CA glue might or might not help just for folks thinking this was an active new thread.

SurferRosa

He started three threads about three different problems. All together, it sounds like a complete cluster ****.

bwilli88 

I have used a triangle file to flatten the taper. It has worked on 2 different NDS crank arms. You need to get any and all burrs out of the taper with an eye to preserve the taper. I had to do this on all 4 flats.

oldbobcat

Or you can buy a new one at your local bike shop for $15.

JohnDThompson 

Taking off too much material can prevent the arm from seating properly on the axle.