pretty scary actually, since it tends to only happen when i am speeding down a hill towards a yellow light.

i've read that chain tension and chainline are the two big things that can cause this, and I was just wondering if people have strong feelings about which is more important, or if it is both in combination. My chainline isn't perfect, but it's pretty close. i had a lot of trouble finding a spindle which would fit weird swiss bottom bracket cup sizes, i ended up pretty close but not perfect. i have horizontal dropouts but in order to get the chain pretty tight i have it all the way back. i am going to try taking a link out to get it shorter and tighter, but if anyone has other advice or ideas about what could be causing this I'd sure love to hear it before i smash into the back of a stopped bus.

btw i am using the SRAM (Sachs/Sedis) PC58 chain pretty new shouldn't be stretched out