Noun
fat bike (plural fat bikes)
(cycling, winter sports) A bicycle equipped with larger than normal tyres and a wider frame to accommodate them, which provides better traction on off-road surfaces such as sand or snow.
Sixth Annual Northland Fat Bike Rally, 9 a.m. to 2:30 p.m., Lake Bemidji State Park; both 10K and 28K routes will be offered. Source: Internet