Cassettes/Freewheels

The Shimano Deore XT CS-M8100 12-speed cassette is optimized with rider-tuned wide-range and close step gear combinations for MTB excellence. - Shift ramp designs provide fast and smooth shifts by HYPERGLIDE+ technology - Light and stiff construction reduces cassette inertia resulting in faster acceleration and increased chain security - Designed with a Shimano Micro Spline body that features smaller and more widely distributed splines to limit cog damage on freehub - Cassette Body Type: Shimano Micro Spline - Cassette Cogs: 10-12-14-16-18-21-24-28-33-39-45-51 - Drivetrain Speeds: 12 - Range: 10-51

- Black polymer spacers - Multiple speed options available - Range: 14-28T - Speed: 7 - Cog Material: Steel

Machined from heat-treated, chrome-plated chromoly, these seriously tough cogs will hold up to massive track sprints and crazy skid-stops. Surly's Track Cogs are strong, shiny and they come in two widths and sizes from 13T to 22T so you can select the perfect gear.

- Extended range aluminum cog for those wanting 1x10 with a full range of gears - Only fits Shimano XT/XTR 11-36t (M771/M980) or SRAM X5/X7/X9/X0 11-36t 10sp cassettes (not compatible with 2011 and older SRAM derailleurs) - Requires removal of the 17T or 15T cog and spacer from existing cassette - Longer B-screw (sold separately) only needed for about 50% of Shimano derailleurs - May require a longer 10sp chain. Very tight fit on Stans 330 rear hub splines - Designed and manufactured in the USA from 7075-T6 aluminum alloy

The product that set the standard and still the best available! The GC line of cassette extender cogs allow you to modify your 10-speed cassette into a wide range cassette. To achieve the optimal shifting, the GCs are optimized for Shimano or SRAM cassette so always select the correct type for the cassette brand you have. Compatibility: - Compatible with SRAM 10-speed cassettes listed on the GC tech page - Compatible with all 10-speed chains - Note that you may need a longer chain that you currently have on your bike - Chain stretch should be less than .5 when installing a new GC - Compatible with all 10 speed rear derailleurs except non-clutch type SRAM rear derailleurs model year 2012 and older - These older rear derailleurs do work with the GC40. - Can be run in 2x configuration with a long cage rear derailleur - These may fit tightly on some over-sized hub bodies such as Stan's No Tubes 3.30 and the Easton X4 hubs. With a little filing and some grease they will go on.