I race on tubies. I've used Dugast and FMB tires for their supple casing, but you probably knew that already. BUT, I am building a new wheelset that will be my primary one for racing, and I wanted your highly educated opinion on tread patterns.
I raced this 09/10 season (two more races to go) with a FMB SSC Sprint 34mm in the rear, and a Dugast typhoon 32 in the front. I was blown away by how well that rear tire with file tread and side knobs stuck to grass and dirt, and did as good as anyone else in light mud. I race in northern California, so we race all but a couple races each year in fairly dry in grass and dirt (little sand, but nothing to dwell on), and never in snow.
Part 1 - Should I consider using a file tread up front as well? I'm mentally drawn to the tread in the front to prevent being thrown to the ground, but have no worries with a little powered spin & slide in the rear. The FMB has a fairly burly side knob, but should I trust it up front or get the "normal" pattern FMB or Typhoon for the wheelset. Anyone who uses a file tread up front please let me know your thoughts, or warnings.
Part 2 - Should I put a 34 up front to match the rear (assuming I go with 34 in back again)? In rereading the CX Magazine and other reports on rolling resistance, lower PSI is simply faster, and that's easier to do in a bigger tire. Bigger is also better except in snow, sand, or deep mud. Guess what I don't get to ride in? Bigger means softer tires, and potentially larger contact patch, though I know most manufacturers have the same tread with a slightly larger casing, so the placement of the side knobs aren't as much on the side on a 34 as they are on a 32.