Top:Agilis crank; Bottom: SABB bottom bracket
Rotor is best known for its funky articulated dead-spot-eliminating crank system. It’s been quietly getting some top race results, but it’s a complicated (and expensive) bit of kit. Q-Rings are Rotor’s simpler, cheaper, no-moving-parts option – they’re a reinterpretation of the old non-round chainring idea, but with added adjustablility by changing the orientation of the rings.
Having produced chainrings, the next obvious step was to make a conventional crankset to go with them. So while it initially seems a bit odd to see the Rotor logo adorning cranks with no linkages in them, it does make sense. And there’s still quite a lot of innovation going on in the Agilis crank.
The cranks are CNC machined from aluminium and drilled out along their length to cut weight without compromising strength and stiffness – Rotor calls it Hollowminium. As a piece of manufacturing goes, it’s not as clever as Shimano’s hollow forged crank arms, but it’s still fairly smart. And then there’s the adjustable integrated axle, which we have to confess we don’t fully understand and will have to look at a real crank to figure out. The essence of it is that the position of the left-hand crank on the axle can be adjusted, while the right-hand one fits on to a seven-faced taper. The idea is that the chainline is finely adjustable, rather than being at the whim of whatever spacers you have to hand.
There’s no claimed weight for the Agilis cranks beyond “very light”, but there’ll be three models for road and mountain bikes.
Of course, once you’ve made a crank you find yourself compelled to build a bottom bracket to go with it, and Rotor’s SABB is a rather cunning development of the now-ubiquitous outboard bearing idea. Plenty of people have found that their bikes just don’t get on with outboard bearing BBs thanks to various species of squiffy BB shell. Rotor’s Self-Aligning Bottom Bracket sticks the bearings in spherical housings (a bit like the ones found in some shock mountings) that let the bearings pivot a little bit relative to the cups and find their own best alignment. They won’t be perfect with everything, but they should be more likely to achieve a better alignment than rigidly-mounted bearings.
The bearing diameters are the same as other people’s, so you’ll be able to run a SABB with non-Rotor cranks. There’ll be a long-life ceramic bearing option, and the bearings themselves can easily be popped out of the cups and replaced. Again, we don’t know how much it’ll be, but it’s certainly interesting. More news as we get it, or keep an eye on www.rotorbike.com.