To be even remotely competitive in the 55+ (I'll be in that age group in 2012) I'd need another 1 mph in average speed. But I think that's do-able, my avg. wattage outbound was only about 240 watts, 220 watts on the return leg, I can get stronger than that. I've averaged 290 watts for a 20 minute effort in a past race.

It's fun trying.