What if you can't spin?

Spinning is more a neuromuscular thing than a cardiovascular one. It's true that those born with fast twitch fibres have the ability to hit the high revs (180rpm+), but anyone can gradually adapt to cadences of 90-100rpm. It's easier to start this process young (hence the restricted gearing of youth racers), but the brain retains more plasticity than people like to believe, even in old age.

If anything, I'd recommend dropping your gear to keep up with the oldboys.

2 Minutes Ago 10:57
dogsballs spin to win, i ride 45x18 or 67" and i take no prisoners. spinning is actually easier, than trying to grind a big gear.

i stand corrected