Racing Speed XLR High profilefull carbon 50mm or 80mm rims. Available as either standard 50mm tubular with steel bearings or XLR version in either 50mm or 80mm. The XLR version comes in standard or dark label options. Fulcrum Dynamic Balance in the rim: thanks to special operation of the production process the carbon fibre layup is positioned in such a way as to obtain perfect rim balance. Racing Speed XLR's feature the top CULT ceramic bearings. The 50mm's have 18 front radial stainless-steel spokes & 21 at the rear; the 80mm version has 16 front & 18 rearboth in Fulcrum 2:1 ratio for greater wheel stability & enhanced power transfer to the rear wheel. Weights: 50mm standard- 590g 770g; XLR 50mm- 577g 747g; XLR 80mm- 715g 825g.