—Big Man Near Campus
Surprisingly, 280 and thereabouts often is not much of an issue. I used to work for a shop that supplied the 49ers training camp, and we had few equipment problems. Most types of bike should work if:
- The bike is good quality—not a WalMart-type "toy" bike
- It is in good working order
- It's adjusted to fit you
- Your riding style is laid back—no curb hopping or attacking the climbs or sprinting for traffic lights
- You pump up the tires to full pressure every week without fail (important)
If you get a road-racing-type bike, put on the widest tires that will clear the frame--such as 28 or 32 millimeters wide instead of the more common 20-23. That will give you better ride quality and fewer flat tires.
If you get a mountain bike, you'll buy yourself some tolerance for a more aggressive riding style.
As with any new rider, you'll probably be more comfortable at first with a wide, cushy seat and high handlebars. As you get used to riding, the typical "sport" seats and riding positions will give you more speed and power.
So the best bet might be to start off with a "comfort-style" mountain bike, which has the wide, cushy seat and high bars. Then later you can change those items in favor of more sporty ones. Later still, maybe you would trade in favor of a skinny-tire bike.