They might still have their detractors, but it’s safe to say disc brakes are here to stay in the road cycling market. And with cycling's obsession with weight and carbon fibre, it was only a matter of time before a company developed an aftermarket carbon rotor.
Spanish company Alpha has done just that, putting its motorcycle expertise into a cycling product for the first time. The result is a one-piece 6-bolt 140mm rotor that weighs a claimed 32g.
Not only are they exceptionally light, but the company also makes claims for improved braking performance in the dry and wet. It also reckons they are more resistant to high temperatures - that’s certainly why they’re used in high-performance motorcars and in motor racing, but does a road disc rotor ever get hot enough to warrant a carbon rotor? They’re claims we’d be very interested in putting to the test.
Such lightness doesn’t come cheap. The rotors are manufactured at the company's own facility in Spain using a ceramic polymer technology. A single rotor costs from €100. It’s offering a full range of sizes from 140 to 203mm, so suitable for mountain bikes as well. You’re also going to have to factor in new brakes pads, they can only be used with ceramic brake pads. The company doesn’t appear to offer any yet, but a few companies do offer them.
To put that claimed 32g weight into perspective, a 140mm Shimano Centerlock rotor weighs 96g, while an Alligator steel 140mm rotor comes in at 72g. Both pretty light, but the lightest rotor I could find during a quick internet search comes from the USA and a company called Carver Bikes. It makes a titanium disc rotor that weighs a claimed 50g and costs $110. None of those alternatives is made from carbon, though, so we’re going to try and get a set in for testing and to see just what they’re like.
Here are the details of the new Alpha Ceramic Rotor RS:
You can read more at www.alphamotocicletas.com
David worked on the road.cc tech team from 2012-2020. Previously he was editor of Bikemagic.com and before that staff writer at RCUK. He's a seasoned cyclist of all disciplines, from road to mountain biking, touring to cyclo-cross, he only wishes he had time to ride them all. He's mildly competitive, though he'll never admit it, and is a frequent road racer but is too lazy to do really well. He currently resides in the Cotswolds, and you can now find him over on his own YouTube channel David Arthur - Just Ride Bikes.