Originally Posted by mack_turtle

the local Austin SingleSpeeders (ASS) group is mostly a mountain bike group. but when it's rainy and the trails are muddy, a few dozen of us gather on "gravel" type bikes for urban riding. there are always a few people on SS bikes at the local gravel races like Castell Grind. I've ridden Castell, Come and Grind It, Holey Roller, Texas Chainring Massacre, and the Hill Country Hundy on SS gravel bikes.
my previous bike was a Traitor Crusade, equipped with 35mm 700C tires, and it had swinging dropouts to tension the chain.

am now on a Twin Six Standard Rando with 47mm 650B tires. it has a PF30 bottom bracket shell, so I put a Wheels Mfg. eccentric bottom bracket adapter in it. works fantastic!
gearing choices vary depending on tire size and terrain, but I have settled on something around 60-65 gear-inches.