Fat bikes are a variation of a traditional mountain bike and can be used on a variety of off-road terrains. Originally these bikes were designed for snow and sand where the larger tyre volume gives more traction.
The wheels on a fat bike are made to take a much wider tyre that can be run at a very low pressure. Commonly a tyre width of 3.8in is used on a rim in excess of 2.6in. Such a tyre allows very low pressure from 8-10 psi.
In the UK Fat Bikes are ideal in soft, muddy or even boggy ground and many obstacles are easily overcome with the large tyre footprint and very low pressure.
Around the world events have been created aimed at fat bikes. Events in Alaska and the deserts of New Mexico were some of the first and now see a large field of entrants.
As with mountain bikes, fat bike frames are usually aluminium or, in some cases, carbon fibre. Unlike mountain bikes there are many fat bikes with rigid forks as the large tyre and low pressure offers sufficient suspension and traction. However, newer fat bikes can be found with specially built suspension forks and the odd full suspension bike can also be found. At speed the balloon tyres can create bounce. In these cases the suspension helps the rider overcome fatigue in the legs.
Fat bikes are now found on general sale around the UK and J E James has a varied selection available from Cube, Kona, Specialized, and Trek.