I ride a Surly LHT with Ultregra/Tiagra and either run 28c Schwalbe Duranos or 47c Big Apples. Not a road bike, but very similar geometry. I also ride a Kona Jake CX bike and have a Peugeot from 1988 I'm converting to flat bars. The only problems I've ever had were with the (AWFUL) stock wheels on the Kona. I've since upgraded them to a $150 set of 36 spoke wheels on Tiagra hubs and they've run like butter.
Currently ~350lb.