If I'm going to build a singlespeed with horizontal dropouts, do I need a bolt-on rear axle or will a QR work? Do I need to worry about slippage or should I get some gizmo to account for that? Never used horizontal dropouts so I'm half clueless.
qr will work, but bolt on is much better. most frames dont have a "gizmo" to prevent slipage, but a few do. its not nessisary. if you really wanted something like that, you could get some bmx chain tugs.
if your using disc brake i feel it is a requirement to use a bolt on axle. other wise the disc brake and cause the wheel to slide on the dropout. i had this happen to me on a ss fr bikei had in the past