How to find a mountain bike that can handle a heavier (250-260lbs) rider? I am a 44 year old man that is very heavy (250&ndash;260lbs(113-118kg)) and I am looking to buy my first mountain bike to do some riding on the weekend to burn off some of this fat I have.
250-260 pounds isn't that heavy.

You may not need to worry about weight at all.

See if you can find the information from the manufacturer about weight limits for their bikes. For a mountain bike that you intend to use for what it was made for, you're probably within the weight limit the bike is designed for.

You may want to avoid the lightest weight stuff (carbon) unless you check the weight specs. But that's mostly stuff on the more expensive bikes.

Some of the parts that normally wear out will likely wear out faster for you than for somebody lighter, but that's no big deal.

If you plan to do tougher things with the bike than it was made for (jump a trail bike, for instance) you could run into problems. Stick with getting a bike that's intended for what you plan to do with the bike.

For instance:

1. Trek Bikes Weight Limits:


  Rider weight limit of 275lb: Road bikes with drop type handlebar
  Triathlon, time trial or Speed Concept bicycle Cruisers with large 26"
  tires and swept-back handlebar, Bicycles that fold.
  
  Rider weight limit of 300lbs: Hybrid bicycles with 700c wheels, tires
  larger than 28c, and flat handlebars City bicycles: hybrids with
  special equipment, cyclocross bicycles: with drop type handlebars,
  knobby 700c tires, and cantilever or disc brakes 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.


2. Specialized Bike Warranty Policy (PDF) (weight info near the bottom):


  Also, some bicycles and components are built to be lightweight, which means they may not be appropriate for riders who are approaching 250 pounds in weight (over 240 pounds, for example). Riders approaching 250 pounds in weight should not ride any bicycle equipped with Specialized-branded composite seat posts, handlebar stems, or handlebars.


In other words: avoid the carbon/composite seat posts, handlebar stems and handlebars and you'll be fine with this brand.

3. Cannondale 2010 User's manual (PDF) (Starting at page 52)


High-performance road: 275 pound rider
General Purpose Riding, Cross-country MTB, Marathon MTB, Hardtail MTB, All mountain, Gravity, Freeride, Downhill, Dirt Jump, Cyclocross, basically everything they make except high-performance road bikes: 300 pound rider, as long as you stick to the intended use. Limit on cargo goes from 5 pounds to 55 pounds