I am using 27 1 1/4 wheels for riding to work. the rear wheel is a factory built alloy with rustless spokes. Over the last 2 weeks i have broken 3. the bike itself is old and wont take 700 cs. The only thing i can think of is to have it rebuilt with d/b spokes Any ideas would be appreciated. I dont use a heavy saddle bag and i"m not particularly fat!