Track bike type mens geometry sloping comfort frame sizes s m l xl bike frame sizes cm 46 49 52 54 56 58 61 cm colour black model 2017 series specialized langster frame material aluminium fork material carbon gear systems without gears with derailleur number of gears 1 front chain wheel teeth 48 chain kmc z510hx brake type dual pivot brakes tektro wheel size 28 inch wheel set axis sport track tyres specialized espoir sport sad