Racing bike type mens geometry sloping comfort frame sizes xl l s m bike frame sizes cm 47 50 53 56 59 62 cm colour black model 2017 series bergamont prime frame material aluminium frame characteristics double butted hydroforming frame alloy 6061 aluminium fork material carbon aluminium gear system with derailleur number of gears 18 groupset shimano rear derailleur shimano sora derailleur model shimano 3500 front derailleur shimano