I have a small tip for the weight conscious swift rider. I used to be involved in bike trials " hopping variety" and there is a class of bikes that use 20" wheels. I owned one of these ultra durable bikes, that weighted less than 18#, largely due to radially laced wheels with drilled rims, ultra light hubs ect. Best of all, the prices are fairly good for the weight. So check out MOD trials bikes, if just for the light rims.

PS. The front rims have a nice width to them and would give a nice profile to a Big Apple tire.