i have an '09 spesh epic and it needs new chain rings bb bearing. i've been looking at replacement/upgrades and am a bit stumped by the choices from shimano. please explain the difference and which one i need. ta
explain the difference please
771 - 48/36/26 tooth
770 - 44/32/22 tooth
And they look a bit different
M770 = standard for most bikes- ie. 22-32-44 chainrings
M771 = designed for touring- 26-36-48 chainrings. Theres a spacer on the axle so it sits ever so further out to aid chainstay clearance.
M771 is good if you plan on running a double+ bash setup, 26/36 is better for that I reckon.
Sounds like you need M770..
as above plus crank lengths vary, 175mm is "normal", 170mm of your shortish, 180mm if your huge
PS the 48/36/22 is "touring" gearing
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