Hi Teppi and welcome!

I'm about your size and I ride a regular diamond frame bike. An Orbea Aqua Dama, to be exact. I questioned my LBS (Bike Gallery in the Portland area) about my weight and possible damage that might be caused on longer rides before I took the plunge and bought the bike. As I was getting fit for the bike, I asked again, and the fitter said that most bikes are built to take more weight than we think. My frame is aluminum and my fork is carbon. I have a Brooks B68 saddle and love it. I just rode 73 miles in a local supported ride yesterday. Yes, there were a few aches and pains associated with a hilly 73 mile ride, but I wasn't uncomfortable. The most important thing is fit. After you get your bike, spend the money on a professional fitting. It's worth every penny!