Your current weight is at the high end of the limits Trek puts on their bikes. Here's the relevant section from the Trek FAQ:
Rider weight limit of 300lbs:
- Hybrid bicycles with 700c wheels, tires larger than 28c, and flat
- City bicycles: hybrids with special equipment, cyclocross bicycles:
with drop type handlebars, knobby 700c tires, and cantilever or disc
- Mountain bikes of all types including: standard, race, cross-country,
heavy-duty, trail, all-mountain, freeride, and jumping bikes of both
the hardtail and full suspension variety.
I suspect that other makers have similar limits. You don't say much about your riding style, so it is hard to be very specific, but there are some things to keep in mind:
- Take time to find a bike that fits you well, it will be much easier to keep riding if you are comfortable.
- Make sure your wheels are well trued and tensioned, the biggest cause of wheel failure is probably spoke breakage caused by spokes that are too loose.
- Find a frame that will take wide tires and use them – wider tires will be able to support your weight with lower pressures which reduce the chance of pinch flats and rim damage. Wider tires will also make the bike more comfortable and by running at lower pressure will reduce the stress on your rims.
Good luck! If you're starting with a bike in decent condition and aren't riding it too hard, I'd guess that if you take care of the items I mentioned above the bike will do just fine. Your weight is going down after all. I wasn't as heavy as you when I started riding again – but I was up there (on the far side of 260). I started on the bike I had – an old steel Trek 530 frame with 32 mm tires (the biggest I could fit into the frame). I'm starting to think I'll be able to break 200 this year.
If you're looking for ideas about getting started on riding again, I'd highly recommend Grant Peterson's book Just Ride. There is good thinking about riding for the joy of it and also some ideas to get you thinking about how to exercise effectively.