Paging velo geeks

Any of you freaks ride single-speeds or fixies, or otherwise spin wrenches on bikes?

I'm having some chainline issues on my Surly ghetto 'crosser. The chain keeps snaking off when I least expect it, leaving me to either nut myself or unclip in a hurry and drag my feet to a skittering, spark-flying halt.

I swear I've got everything lined up right, but at least once per ride the chain will pop off. The setup has been bombproof until now.

Chainring looks straight, chain looks OK...anything I'm missing, besides maybe the concept of taking this to a bike forum?

How old is the chain? You know that you're suppose to set the wheel farther back the longer you have the chain on to compensate for chain-stretch? That's why single speeds use those long horizontal dropouts. If you haven't already, try setting the rear wheel just a little farther back. Good luck and please keep me posted, I have two single speeds, including the Surly RatRide 1X1.

http://us.news2.yimg.com/us.yimg.com...ds_cpth102.jpg

Yeah, Viva's probably right. You just need a little more tension (but not too much) on the chain.

Yep, new chain ought fix the sitchuation. My wheelbase has increased about a centimeter over the last year - chain's probably had it.

Thanks.

And Mudsy, nah, my preferred style is more along the lines of this:

http://www.snibbor.net/pmag/cycle.jpg