Hope T-Rex Ratio Expander 40T Cog for Shimano
Hope says in their opinion the 40t worked much better than a 42t as far as making that last big jump between the 36 and the largest cog on the cassette. It needed less B-tension adjustment and just seemed to work better so they ditched the 42t in favor of the 40t. Machined out of 7075 aluminum, the T-rex comes in Shimano or SRAM specific versions which will be installed without the need for spacers. Like all the other models, you will jettison the 17t cog to make room for the 40t.