powitte

I'm having some trouble maintaining adequate chain tension on my IGH bike. I can get it where I want it and very firmly tighten the axle nuts down with the closed end of a 17mm box wrench. Over the next several rides though it goes progressively more slack. I am a bit obsessive about this now since last year I took a bad spill from my chain falling off over a rough patch of road when I had been sloppy with the chain tension.

My only thoughts are that the "serrated" washers are more just like shallow grooves rather than teeth. Might this be part of the problem? Any other thoughts?

If it matters, it's a SRAM S7 with stock cog in the back, Sugino alloy ring up front, 1/8" Izumi chain.

FastJake

So you've determined that the axle is slipping in the dropouts? Sounds like you need some tracknuts. Or just crank those nuts down more. I've run quick release rear wheels in horizontal dropouts and with a fixed gear drivetrain, I've never had a problem.

Sci-Fi

If you have horizontal dropouts, you could consider going old school and buy "chain tug(s)". That should keep your adustment w/o having to over tighten the axle nuts or if track nuts didn't work.

powitte

Sorry, should have mentioned this is a coaster brake set up.

BCRider

I'd start by determining for sure if or not the axle is shifting. Set the chain tension and put a bit of nail polish, paint or even a felt marker across the axle nut and dropout joint for a witness mark. Then ride it for a while and when you notice the chain is loose look at the mark to see if the axle has shifted or if the slack is due to chain wear.

Nail polish or latex house paint is easily removed later on but will stick well enough to use for this test.