Bicycle frames are constructed from materials which place emphasis on being strong, lightweight and stiff to aid power transfer. Aluminium, titanium, steel and carbon are widely used in all levels of frame production.
Track frames are built for single speed use with a fixed gear. They have horizontal rear entry drop outs and a higher bottom bracket for clearance on the banking. Over recent years single speeds have seen a surge in popularity, no doubt due to the large amount of couriers using them, many people are adopting single speeds for commuting and training on through the winter months. The fixed gear nature of a single speed teaches you to spin the pedals smoothly on the flat and power over inclines, as there is no hiding on a single speed. You can even find people Time Trialling on them on some of the flatter courses. With a single speed you get a versatile bike suitable for training on through the winter, commuting all year round and then racing at the velodrome on.