“Ting, ting, ting!”
It’s the sound that many roadies with disc brakes are all too familiar with, especially on longer descents. When disc rotors get hot, they can sometimes warp just enough to make light contact with the pads, creating that telltale soundtrack until things cool down a bit. Shimano had already officially agreed to use its more robust mountain bike rotors for the latest generation Ultegra Di2 and Dura-Ace Di2 electronic groupset to address the issue, but now the company is announcing two road-specific rotor designs that offer a better aesthetic match.
According to Shimano, the new RT-CL900 and RT-CL800 have a “sturdier alloy carrier and arm shape” that “significantly reduces heat distortion during long, steep descents.” Essentially Shimano claims the new rotors are better able to hold true when they get hot so pad rub doesn’t become an issue.
The new rotors will only be offered in 160mm and 140mm diameters for now and will also feature Shimano’s long-running Ice Technologies Freeza design cues, including a three-layer sandwich design with steel braking surfaces and an aluminum interior connected with cooling fins to dissipate heat.
Claimed weight for both rotor models is identical at 114g for the 160mm size and 96g for the 140mm size (which, interestingly, is a few grams heavier than the mountain bike rotors Shimano has previously recommended for Dura- Ace and Ultegra). Retail price is US$86 for the RT-CL900 and US$61 for the RT-CL800. Pricing for other regions is yet to be confirmed.
More information can be found at bike.shimano.com.