Singlespeed & Fixed Gear - crank arm loosening...

My drive side crank arm loosens periodically at the BB bolt. There's no back & forth play, it just shakes a little from side-to-side. I'll stop, re-tighten the crankbolt, and continue on my way. I've read up on other posts about how it could be my crank or the BB spindle deforming, necessitating a new crank arm or set as well as possibly a new BB. But this thing is almost brand new, maybe 30-40 miles on it. I haven't taken the cranks apart yet, thought I'd throw this out there first. I've been practicing skid stops a bit, is that the culprit? I wouldn't be surprised if it was except for the fact that the cranks and BB are pretty fresh and not old and beat up. I've torqued everything down to just short of stripping the threads (I think :rolleyes:.

"I've torqued everything down to just short of stripping the threads"

by 'torqued' you dont mean to an exact measurement of torque right? just checking.

No, sorry. Just meant to say that I've screwed everything down to the point of total resistance. I've never had any problems with this in terms of threading, so I don't think I've stripped anything (knock on wood).

Well, I guess I'll take this up with my lbs, probably the best thing to do anywyas.

Take that crank arm off and make sure you haven't damaged the taper. Honestly, I bet you have.

If the taper is even a little bit ovalized, it will almost always work itself loose.

My drive side crank arm loosens periodically at the BB bolt. There's no back & forth play, it just shakes a little from side-to-side. I'll stop, re-tighten the crankbolt, and continue on my way. I've read up on other posts about how it could be my crank or the BB spindle deforming, necessitating a new crank arm or set as well as possibly a new BB. But this thing is almost brand new, maybe 30-40 miles on it. I haven't taken the cranks apart yet, thought I'd throw this out there first. I've been practicing skid stops a bit, is that the culprit? I wouldn't be surprised if it was except for the fact that the cranks and BB are pretty fresh and not old and beat up. I've torqued everything down to just short of stripping the threads (I think :rolleyes:.

Buy a new crank, your old one is shot. Chances of it being the actual BB are slim to none as they are both new....er. Steel BB VS aluminum crank? Hmmmmmm.... ; )

Even though it's almost new? I mean, it's not like I've got thousands, or even hundreds of miles on this thing. Maybe 30, 40 tops. I figured stuff like that happened when your cranks are well ridden, and accumulated pedaling/climbing/skid-stopping puts enough force upon the taper for it to deform. I hope that's not the case. :(

When stuff is improperly installed, it has a tendency to wear out/break quickly.

But yeah. Take a look to make sure it's actually ****ed before you go out and buy something else.

Cranks don't wear out the BB, ever. Your crank is always ****ed.

If you can't afford a new crank arm, try a new bolt. Some bolts are slipperier than others. I found a titanium bolt - which are grippier (in fact, they can seize, so be careful) and my cranks have never loosened since. Also, the old Campagnolo bolts with the 15mm bolt head grip well.

I went home, took off the crank arms and took a look at it. There doesn't seem to be any rounding inside the taper that I can see, although if it's very slight I suppose that's something that would need more a more detailed approach towards diagnosing. But there was no play in any direction after my ride home. Guess I'll cross my fingers & chalk it up to skid practicing, until it happens again :\. Much thanks for the advice, I'll take it all into account if his does become a repeated problem. Oldsprinter, can you clue me into where you found your titanium bolt? I'd probably try your way first.

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Sweet! Thanks Soil Sampler.

erichsia, i'm having the same problem now with my non-drive side. frustrating as hell because of the creak. i've taken off the crank arm from the bb spindle, cleaned it, then re-greased the spindle and put it back, making sure to tighten the bolt properly. it's now a week later, and it's creaking again. probably later this week, the arm is going to come loose again. i just hope i don't have to replace the arm entirely.

From my experience, if a crank arm comes loose, it is pretty much hosed.

My trials bike has a hosed ISIS crank, along with my Pista.

The trials crank keeps coming loose, the pista stays on, but will never go on straight again (tried every possible way to get it back on straight).

The one exception I've seen is with self-extracting bolts - I have a set of cranks that had the non-drive arm loosen up, twice (luckily both times I had enough foresight to get off and walk it rather than trying to keep pedaling. I was sure I had wrecked the arm, but it seemed to be fine. After the second time I unscrewed the bolt and replaced it with the standard 14mm one, and blam, never happened again. Eff those things.

erichsia, i'm having the same problem now with my non-drive side. frustrating as hell because of the creak. i've taken off the crank arm from the bb spindle, cleaned it, then re-greased the spindle and put it back, making sure to tighten the bolt properly. it's now a week later, and it's creaking again. probably later this week, the arm is going to come loose again. i just hope i don't have to replace the arm entirely.

That sucks man. what kind of cranks are they? I have Sugino RD's, which are already throwing my chainline off as it is. This could just be a blessing in disguise to go out and get some cheap Andels/Aliens/Soma/whatever, or spring the money for 75's. Anyone have good expericnes with the Miche cranks, ones with 135 bcd? I've heard the downsides to them, but they're cheap as hell on bikeisland.