I'd worry more about what length Category 5 race lengths are, since that's what you'll be racing. I'd say maybe 20-30 minutes for a Cat 5 crit, and around 20-35 miles for a road race.

Since you asked, Category 1 races (which are usually Pro/1/2 races) are around 60 minutes criterium and 70-80 miles road race, but of course there are exceptions.