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TECH NEWS
alpha carbon discs5.jpgThe World's lightest disc brake? Spanish company unveils 32g carbon ceramic disc rotors
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.
- Everything you need to know about disc brakes
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:
- More powerful and progressive braking
- No vibrations
- Ultra lightweight
- Better resistance to high temperatures and exhaustion compared to conventional discs
- Superior performance
- Efficiency dry and wet
- 1.9mm thickness
- Manufactured in Spain
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.
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25 comments
I think you're all missing he fact they wouldn't bend under braking so would be likely to never have rubbing issues. Worth it just for that I'd say.
No it isn't. The vast majority of them are stainless steel. Shimano ice rotors are aluminium cored but faced with a thin sheet of stainless steel on each side. This is one of the reasons they yowl in the wet. The grey iron used for brake discs in cars has a very high self-damping property that stainless steel doesn't.
At first I thought this was a crap idea, but actually, braking on steel rims is pretty bad, so maybe these do hold an advantage over steel discs. However, as said above, these are definitely not the same as the carbon-ceramic rotors used in motorsport
At any rate, I wouldn't buy them without someone trying them for me first!
I'm pretty sure some American guys have already got carbon fibre disc rotors in production and apparently they work pretty well if you bed them in according to their instructions. Will try and find a link when I've got more time.
Here it is.
I would definitly try them if they make shimano centre lock compatible ones.
Its laughable
Many carbon clincher rim exploded when descenting due to rim brake high heat accumulating
What they think this carbon piece of sht will do better?
..because rims and brake discs aren't made the same ? .. because carbon brake discs have been used for years under massively higher loads and temperatures and work fine ?
Carbon rims generally blow out due to a pressure difference working on a weakened structure, in turn due to the resin softening under extended braking. There's nothing beyond normal atmospheric pressure on the outside of the rim to stop it bulging, these discs are designed to be more rigid (more brittle as well I believe), run at higher temperatures, using a different material mix and are under compressive load from both sides from the calipers - so the whole environment is different as is the material itself.
That would be some of my first guesses...
So if I swap my alloy caliper brake rims to carbon then braking will allegedly be worse.
If I swap my alloy disc brake surfaces to Alpha carbon units then I get more powerful brakes.
Perhaps Alpha should be applying their skills to caliper brake surfaces and then I can dump my disc brakes?
Or is it just a load of BS?
rim braking = abrasive friction, large surface area, low caliper force.
disc braking = adhesive friction, smaller surface area, high caliper force.
the tests of other carbon rotors showed lower initial bite compared to steel surfaces, but higher braking force once operational temperatures were achieved.
Doh...should have looked for P&P - thanks ClubSmed.
Bearing in mind that all previous iterations of carbon rotors for bikes have been garbage I think I'll let someone else guinea-pig these.
They also come out a good percentage thicker than steel rotors so a lot of calipers may have problems with them. You also need special ceramic pads apparently.
I'd definitely be open to trying them but how's about a test first?
Appears they have put them on their site and accordingly the prices are:
Carbon Ceramic Brake Rotor Disc Alpha RS 203mm = USD 98.60
Carbon Ceramic Rotor Disc Alpha RS 180mm = USD 78.45
Ceramic Brake Rotor Disc Alpha RS 160mm = USD 68.55
Ceramic Brakes Disc Alpha RS 140mm = USD 58.65
The above comes with a caveat they are discounted at the moment and I do not know the P&P charges. That said, they appear real good value even with the current exchange rate.
I am tempted.
$9.95 to the UK
I can't see these being particularly dangerous. They're made of woven carbon fibre so, barring a fairly extreme accident, they would probably stay largely in tact in the event of a crash. I suspect the refence to 'ceramic' in the name refers to some kind of ceramic particles added to the epoxy, possibly to increase the heat tolerance.
That's kind of a valid point but racing car carbon rotors are made from a material called carbon-carbon which is a totally different beast to the epoxied woven carbon fibre these rotors appear to be made from.
Returning to the vexed subject of disc brakes being "more dangerous", might these ceramic rotors be brittle i.e. likely to crack/fragment on impact?
If so then you would have properly sharp pointy bits bouncing around a mid-peloton crash.
Any materials engineering experts out there know one way or the other?
Just because you can doesn't mean you should. If you are that concerned about weight use lighter inner tubes, don't drink any beer - ever plus plus plus
the down sides of using carbon are pretty extreme. I recall seeing the carbon disc failures on cars, it isn't a slow process!
Just because you can doesn't mean you should. If you are that concerned about weight use lighter inner tubes, don't drink any beer - ever plus plus plus
the down sides of using carbon are pretty extreme. I recall seeing the carbon disc failures on cars, it isn't a slow process!
Python, most rotors are made of stainless steel. Shimano ice rotors are aluminium faced with stainless steel. I'll take a set of these if they're guaranteed not to yowl in the rain (and if they don't cost eleventy million pounds a set, which they probably will!).
The point about heat is a good one, the heat has to be dissipated or you're in trouble. There was an article on bike rumor a while ago about a guy who fitted superlight rotors on his Road bike and boiled his brakes on a long descent and had a spectacular crash.
Interesting idea, but I'm not sure whether there could be issues with heat build up in the caliper, as these surely don't conduct heat away like metal rotors? I suspect they might be more suitable for an XC MTB (as per the photo?) or CX where heat build up is less of an issue due to shorter descents on race circuits and lower speeds.
Centerlock version?
kettle cycles had the SiCCC, i think 40g per rotor. and then scappa, with their funky G2CS inspired design as well.
looks like something you cut out from the back of a cornflakes packet
Looks pretty fugly to me
ill stick to alloy ta