I am curious why you would be breaking spokes on the rear wheel. I run similar wheels and I weight 260 lbs
. My 2000 Jamis Aragon has been almost trouble free and I just bought a used Roadmaster step through frame with 700C rims. I check spoke tension by plucking them like a guitar string to make sure the tension is even. They should have a 'middle C' ping rather than a thung sound. Do they break near the hub or near the threads?