Single-speed bicycle on the situation, a messenger may prefer a mountain bike based single-speed, which can roll over many obstacles, or a fast and light road bike-based single-speed. In the United States market, bicycle companies such as Bianchi, Cannondale, Fuji Bike, KHS, Kona, Raleigh, Giant, Specialized, Swobo, Felt, Trek and Niner all have produced and marketed single speed bicycles. Because most full suspension frame designs either have a single pivot that is not concentric with the bottom bracket, or a linkage with a variable center of rotation, the distance between the bottom bracket and rear axle varies throughout the suspension's travel. This
Roadster (bicycle) due to the resurgence in the bicycle as local city transport where the roadster is ideally suited due to its upright riding position, ability to carry shopping loads, simplicity and low maintenance. In the United Kingdom, there are a number of bicycle manufacturers (such as Pashley Cycles) which make updated versions of the classic roadster and many more are imported from the continent, such as those from Dutch manufacturers such as Royal Dutch Gazelle. They are popular as student transport at universities, especially at Cambridge and Oxford, and are increasingly seen in other British cities, including London. In Australia, there