one thing he could do is get a bike where he can have 2 gear ratios on the bike. like a flip flop hub, or cassetes that have 2 different size cogs as one piece.(sorta like the surly dinglecog and i've seen free wheels like that too) If he does horizontal drop outs, they may long enough to do 2 ratios on the same chain length. have one ratio for commuting and run the seat high, the other for tricks and have the seat low.