Originally Posted by
flargle
Standard road gearing with a 25 cog in back actually works fine for cross racing. You'll spend the majority of your time in the little ring. You might wish for a gear somewhat lower than 39/25 once in a while, which is why a lot of people (like me) use a 12-27 cluster, tho I actually use a single 42 ring for racing.
One strategy that seems to make sense is to have two rings, but very closely geared, like say a 36 and a 44, and basically use one or the other depending on the course. Fast, "grass-crit" style course, stay in the 44, a really muddy sandy mess of a course, stay in the 36.
I also use a 42 x 12-27. that gives me a speed range of something like 4.5 to 28+ mph until I spin out.
it's not that 53/39 can't work- but the large chainring size jump is slower to shift and most riders wouldn't use or need the large ring.
according to this page:
http://www.cyclocrossworld.com/BOSS.cfm
tim johnson uses a 46/42...
sven nys 48/39...
lars boom 42 single
barry wicks 46/42.
so, 46 or 48 seems to be enough for even the best pros. or even 42 for the current world champ.
(at least in his U-23 race, the last WC was super fast)
For the majority of riders, I think a 38 or 39 single might even be better than 42T.
marc