THE REX 2.1S are impressively stiff, lightweight and multi frame compatible, even if you don’t buy into Rotor’s asymmetric chainring concept.
They’re made from 7075 alloy rather than the 7055 used on the pricier REX 1.1s, which adds 42g. But they’re still relatively light, and the internally triple-drilled arms are just as stiff under power. The cunning reverse crank-cap makes them easy to get on and off, and the oversize axle syncs with a selection of BBs to fit all frames. Check spacing and clearances though – the straight arms don’t give much chainstay space. The oval QX1 rings have to be bought separately and can be moved between three positions to alter their unique, dead spot minimising feel. If you’re not convinced, SRAM spiders are also available.
WEIGHT: 600g
ARMS: 170, 172.5, 175mm
Price 402$