Originally Posted by
JeffOYB
I'm still messing with my single ring concept. I was going to get a track ring but people tell me they are thicker and meant for a thicker chain. True? Will they work OK with regular chain? Hmmm, I'm using a 10sp cogset back there.
It seems to still fall off occasionally and I'm almost always in a middle cog. I was wondering if it might be related to my using an old Jubilee rear derailer. It certainly wasn't doing much with chain tensioning. So I've installed a newer derailer -- it's long-cage even. I re-added some chain, too. I haven't ridden enough to know if it's a fix or not. Well, it has dropped ONCE with this new setup but that was soon after I took it out of the car so who knows. It was dropping most when doing intense riding at my max output. (Argh.) But it didn't the last time. ...Just once right at the start.
Maybe there are flat non-track rings? I'm guessing that's what the Surlys are.
Chains drop when they try to "shift" off the side of the chainring. This always happens where the chain is moving onto the chainring. The RD sits after the chain has already come off the other side of the chainring, and will have nothing to do with chain drop. Even the tension it provides is mostly to keep it on the rear cogs, not the chainrings. You pedaling provides the tension for that. If it's providing no tension at all, some slack might appear between the cogs and chainring when coasting or backpedaling, but that doesn't sound like when your chain is dropping.