Single speed - I recommend the Karate Monkey or Ogre. I was 280ish when my thyroid was diagnosed. Karate Monkey was the bike I used to commute and get health again on. The complete is reasonably priced and I regret that I sold mine back in the day. Bike is still getting good mileage from its new owner (and friend of mine) and he's not a tiny guy either. Bike has taken a beating and has disc brakes that were amazing. The 2012 model has a step down on the quality, but still a good value.