What part do i need to repair this?

[bws2158]

i was riding down the road, and all the sudden i was pedaling funny. next thing i know, my left crank falls off the bike. the crank will go back on, but won't stay in place. i was hoping someone here could tell me what i would need to ensure the crank stays put? i searched the side of the road for a washer, or something like that, but couldn't find anything. it could have slipped off a mile or two back.

thanks ahead of time for any help. it's starting to get warmer up here and id really like to have my bike up and running again.

[GeorgeET]

Look in the hole it should have threads. What you need is a bolt with a large flat head or a bolt with a large washer. Measure the depth and get one a bit shorter but long enough to engage all the threads.

Go to a bike dealer or take it to a hardware store and get a bolt that fits. and a large washer to hold arm in place.

Unusual to me crank.

[Painkiller]

and oil your chain on a regular basis

[bws2158]

right, i'm embarrassed by the chain. i left it outside all winter, which is also dumb and negligent. i'll be getting a new one of those too i'm sure.

thanks george. i live in the upper peninsula of michigan and there aren't any bike shops around, but i'll try the hardware store down the road. if that doesn't work i'll have to make a bit of a road trip.

[RobAR]

I hate to argue with my old buddy George but, you're not going to find that at any hardware store. You have lost your "Crankarm Fixing Bolt"; a fairly specific bolt.
You have a Truvative crankset, made by SRAM (also RockShox and Avid stuff) and it looks to be a BB30 with ISIS splines. If you can find a model # on the crankset, go here -

http://cdn.sram.com/cdn/farfuture/pucm0oR7cfZUJ_jrKLWr20Zu_NvZOvZVhUF3D3HdD4M/mtime:1310410943/sites/default/files/techdocs/2012_truvativ_spc_rev_a.pdf

You will want the part number in order to call bike shops in advance of wasting time and gas. It is a fairly common part, though, and any decent sized shop probably has a few in stock. My bet is on it being QBP part # CR2195 but I can't say without seeing.

A reminder to Everyone - check these bolts every time you check tire pressure! It's just routine maintenance, not a design flaw.

[GeorgeET]

Ye Robar , it does not surprise me. I was in a bike store looking at two boxes of axle nuts and could not find any to fit my bike.

Could not see a photo of the part in question.

Hey I did suggest a LBS first.

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BTW , good eye PK.