Road riders on a 12-speed Shimano drivetrain who want a 34T low gear for hills and long days.
This is the Ultegra CS-R8101-12 in the 11-34T spread: twelve nickel-plated steel sprockets running 11-12-13-14-15-17-19-21-24-27-30-34T. It uses Shimano's HYPERGLIDE+ shaping, which is designed so you can change gear under full pedalling load, even during a hard effort on a climb.
The 34T low gear suits hilly roads and long days out, while the close steps through the middle of the cassette help you hold cadence on rolling terrain. It fits Shimano 12-speed and road 11-speed freehub bodies, so many existing wheels can take it, and it needs a 12-speed HG chain.
34T low gear
A wider spread than the 11-30T version of this cassette, for steeper climbs and long rides.
HYPERGLIDE+ shifting
Shaped for smooth shifts up and down the cassette under maximum pedalling force.
12 steel sprockets
Nickel-plated steel sprockets on two aluminium spider arms, with an aluminium lock ring.
Fits 11-speed road freehubs
Works on Shimano 12-speed and road 11-speed freehub bodies. Shimano lists an average weight of 345 g.
Cassette
Fit and build
HYPERGLIDE+
Shimano's shifting technology, brought to the road with 12-speed. It is designed so you do not need to back off to change gear, even during a maximal effort on a climb.
Great for
Maybe not for
This is the 11-34T. The 34T low gear needs a rear derailleur rated for a 34T largest sprocket, so check your derailleur in Shimano's compatibility chart before you buy. Use a 12-speed HG chain. Shimano also makes this cassette in 11-30T.
Check capacity, chain and torque
A 34T low gear can outgrow the derailleur or chain you have now. Check the derailleur's largest-sprocket rating, fit a 12-speed chain sized for the new gearing, and tighten the lock ring to the 40 N·m marked on it.
