If being the fastest to the top of the mountain is your goal then the scott spark rc 900 world cup full sus is the bike for you the combination of 29 wheels and carbon frame make this xc bike excel an ultra lightweight frame is the heart of this racing bike made from scotts speciality hmx carbon fibre it is stiff strong and is featherweight a tapered headtube and internal cable routing keep things tidy while a carbon rocker link drives the trunnion rear shock and boost 148x12mm spacing