I run a single 42 with double bashguards to keep things on track. Seems to work good. I rarely have lost a chain on this bike.
In the back I run either 13-26, 12-25, or 11-25. This is a campy setup but all good so far. Just got the 11 cluster this year to give me a bit more meat to grab on the flats. We'll see how that works out lol.
I tried a single ring and never could get it adjusted right and keep it there. It would work great for one race, during which the watcher got knocked out of place, so it would start dropping the chain in races (on training rides I was never delirious enough to knock it off). The 42 tooth ring was a little large for my rabbit cadence.
Last year I put the derailleur back on with a 38-46 combo for a nice tight chain. I love it.
i bet a guard, a good watcher (n-gear), and the right tension and chain length would avoid this problem...or double guards. But that doesn't mean it's better.
Two rings is certainly a lot more versatile for those of us who ride our bikes not just at 'cross races. I sometimes commute or mtb-ride on mine, and like the double rings. I personally prefer a wider range, either 36/46 or 38/48 for this reason. If am going to deal with the extra weight I want more usable gears out of it. The # of gears that overlap in something like a 38/44 is pretty big...prob for most 'cross races it's fine but for the occasional road section I like the extra range.
Going to try single this year. 42 w/ 11-26 or 11-25.
I am running a outer CX World Guard and an 'N Gear watcher on the inside (this is the best one by far!). Maybe another guard if there are chain issues, we will see.
This is only for the "race" bike. I have another cross rig with a 36/46 and H2O cages. I agree that single rings makes the bike much less usable in terms of riding, but I think it will kick butt in the races! And it looks pretty mean!
I'm running a single 42 with an outer cxworld guard and a 12-27 (no inner gaurd or third eye, etc). I dropped the chain once last weekend racing, however have ridden it pretty hard on the trails without any drops so it probably was operator error. We'll see how she holds up at this weekend's race.