Metron 81 SL Tubular - The Metron 81 SL is Vision’s Aero Triathlon and Time Trial focused wheelset. Vision’s complete wheel system has a 24mm rim width, direct pull bladed spokes, 6 sealed cartridge bearings in P.R.A. hubs, ABS brass nipples, 2 to 1 lacing, CFD / wind tunnel proven aerodynamics, and 100+ pro-podiums since its release.