Carbon ceramic disc brake rotors have been used in aerospace applications since the 1970s and in motorsports since the ’80s. Brembo provided them for the Ferrari Enzo in 2002, and now Lamborghini, Mercedes, Chevrolet (Corvette), Aston Martin and others use them in production cars and on the track.
The benefits are improved heat dissipation and increased longevity, not to mention less unsprung weight.
Now, finally, we’re about to get our hands on some for bicycles. Kettle Cycles just launched their Kickstarter campaign to bring their SICCC disc brake rotors to market.
SICCC stands for Silicon Carbide, Ceramic and Carbon. The Silicon Carbide provides the friction, Ceramic manages the heat and Carbon keeps the rotor strong, stiff and light. How light? Their SFL one-piece 140mm rotors are as light as 40 grams!
Video, tech and more pics below…
As the photo at top indicates, two models will be offered. The one-piece SFL version is the premium piece since it requires a bit more production time and more of the premium materials. SFL means Super Feather Light officially, but is more likely to result in you saying So F–kin’ Light.
Co-founder Josh Gore says the whole reason for the two piece rotor is to reduce the amount of SICCC material used, which is a more expensive material than using just carbon fiber for the spider.
“We started with a two-piece design, thinking the product would be too hard and too expensive to produce as a one-piece,” Gore told us. “It’s more complex to lay up the material using the thin cross sections needed, but during testing we discovered an alternate manufacturing process that let us do it more efficiently and with less wasted material. And, since we could make a lighter version, we thought we really should. It seemed a shame to have the ability to do it and not do it, even if it did cost a bit more.”
“Normally, with something like a SICCC material, you’d see people laying up a solid piece then machining away the excess. But that means there’s too much good material going to waste and we didn’t want to do that.”
For the two-piece rotors, the spider is a special carbon fiber that was developed just for this project. What’s different about it isn’t something they’re willing to divulge yet, but it’s tailor made for the application…and it’s something they’re already looking at using on other components in the future.
Target weights for the one-piece SFL rotors are 40g (140mm) and 55g (160mm). Two-piece rotor weights are 60g (160mm) and 75g (180mm). A 200mm rotor in both formats are planned, but weights are TBD.
The rotors will be made in Illinois, about an hour northwest of Chicago, from US-sourced raw materials. Josh and partner Aaron Stephens developed the manufacturing process and will, at least initially, oversee production in a very hands-on manner to ensure the rotors are made to their spec. They own the machinery and will personally train any future workers. The only process they outsource is the grinding of the rotor surface after finishing, which is done to ensure the braking surface is perfectly flat.
One of the challenges with producing brake pads like this is getting the mix of ingredients right.
Carbon-carbon rotors and even some carbon ceramic blends need to “warm up” to have proper friction. The manufacturing design used by Brembo uses carbon chunks, which wouldn’t have the necessary structural integrity. Kettle uses long fibers in a woven pattern, which gives them the strength they need to keep the rotor stiff – particularly important for a rotor with such a thin cross section compared to car rotors.
“It really was the perfect storm of components and chemistry to get this to work for the bicycle,” Stephens said. “That’s our strength, being able to solve problems and find the right partners. Our chemist is super excited about this project and really helped us make it work.”
The benefits seem worth the effort. The main boon to using a carbon-ceramic blend is heat management. With steel rotors, a lot of attention is given to channeling heat away from the pads and braking surface, but you’re still left with a material that holds heat and, during repeated or sustained braking, essentially becomes a heat source.
Ceramics, on the other hand, are very poor thermal conductors. Sure, they’ll heat up during braking, but then drop all the heat almost instantly.
Think of it this way: Imagine steel rotors as water in a microwave. As you heat the water, the molecules get hyperactive and the water remains hot for a long time. Conversely, imagine that as soon as you turn off the microwave the water molecules stopped moving and it immediately went back to room temperature. That would be ceramics. They’ll take their share of the heat away from the pads and pistons during braking, and then immediately release it into the air.
Since the rotor, as a whole, is thermally inert, even under extremely aggressive braking, it theoretically provides consistent, fade-free braking…something we’re eager to test soon.
Gore says they’ll also handle much higher temperatures than steel rotors. And for durability, Gore says they’ve experienced negligible wear on the rotors during testing, even in sloppy, muddy, wet, dirty conditions.
“As an example, when the SICCC rotors are ground, they’re ground smooth with a diamond abrasive,” said Gore. “Actually, silicon carbide is generally used to grind other materials like metal, etc. Even on some of our high temperature test sessions, we didn’t see any measurable wear. It’s really quite impressive.”
Stephens added: “They’re going to last a really long time. They’re never going to glow red like in the video, we just wanted to test that, and after we pulled that rotor off, it had no measurable wear. Even so, it shouldn’t wear pads much faster than with steel rotors, but our rotors will definitely win. Oh, and during that test in the video, we used SLX brakes and still had the same stopping power at the highest test temp as we did when they were cool.”
The initial grab and overall feel of the brakes can tailored by pad selection. Stephens said they considered and tested proprietary pad compounds, but they wanted to “drop in solution”, meaning it’d work with OEM pads from whatever brake brand you’re using.
Stevens: “Basically, if you’re using good brakes, these rotors are going to make them work better.”
He also said modulation is really good, and they’re quiet. When they first get a little wet, they may make a bit of noise, but during normal braking they make a cool sound, almost like a knife on a sharpening stone at a whisper volume. They recommend bedding them in properly, same as you would with any steel rotor.
The rotors are intended for all applications – DH, XC, road, cyclocross, whatever. They also said they tried everything stupid they could to destroy them -drilled holes in them, ran ’em with three bolts- and just couldn’t get them to fail.
Stephens: “We don’t really believe in weight limits and things like that. Either it’s a solution or it’s not.”
This might be the best part. The one-piece SICCC SFL rotors start at $99, and the two-piece models at just $79. Prices aren’t 100% set for the different sizes, but expect a modest increase as diameter grows. Gore said just because there’s some amazing tech here doesn’t mean they need to be outlandishly expensive. We like that thinking.
Interested in getting a set and helping them get the project off the ground? Check out the Kickstarter page here and their website. The Kickstarter campaign runs through December 3, and the target ship date is in January. The design is complete and they have all the machinery, the campaign is primarily to fund materials purchasing and finish up the final tooling.
Just for fun, here’s a How It’s Made segment on Brembo’s carbon ceramic disc brake rotors: