Update: Exclusive CX75 mechanical disc brake photos and specs added, price estimates for wheels updated.
As seen with the introduction of the CX70 cyclocross component group in 2011 (reviewed in Issue 16), the Japanese component giant Shimano has started to take cyclocross seriously, and today at the North American Handmade Bicycle Show (NAHBS) in Sacramento, the company has unveiled a new mechanical disc brake for cyclocross racers that is scheduled to be ready for this fall.
The CX75 disc brake is said to offer 30% more power and a 20% smaller profile than the R505 mechanical road disc brake (reviewed in Issue 15). The cable pull is optimized for the Super SLR STI shift and brake levers, and is to be paired with the RT81 Deore XT-level mechanical disc brake rotor. Shimano’s Dave Lawrence, road product manager, told Cyclocross Magazine that the new caliper will be approximately 160 grams per wheel, putting the brake close to Tektro’s 148 gram Lyra disc brake caliper and Avid’s 155 gram BB7 caliper.The company will also be offering a Tiagra-level R515 mechanical disc brake, which will be paired with an SLX-level RT64 brake rotor. This model will also offer increased power and a lower profile. The two brakes share the same mold, but the CX75 will be about 20 grams per caliper lighter due to some extra machining. The CX75 should have both a higher finish quality and extra seals for wet weather use.
It’s a logical move for Shimano, as higher-end mechanical disc brake allows builders and bike manufacturers to spec existing cable-pull brake levers, while road and cyclocross hydraulic levers are still being developed. It’s also an easier product to maintain and avoids hydraulic brake fade due to brake fluid overheating.
Cyclocrossers should also take note that Shimano is releasing wider-range capability to its Ultegra, 105 and Tiagra component groups. All short-cage rear derailleurs and the Ultegra medium cage rear derailleur will accept up to a 30 tooth rear cog, while the mid-cage rear 105 and Tiagra rear derailleurs will accept up to a 32 tooth cog. Of course, Shimano will also offer 12-30 tooth Ultegra cassettes to take advantage of the expanded range.
On the wheel side, Shimano has added another road tubeless wheel, with the WH-RS61 tubeless wheelset that slots in below Ultegra and helps bring the technology to the masses. Price for the wheelset should be around $500. We’ve been riding a Hutchinson Bulldog tire on Easton’s Road Tubeless wheelset with much success and tubular-type pressures, and expect tubeless to win more converts in the next few years. The big setback? Hutchinson has temporarily stopped making its carbon-bead tubeless-ready tire, although many are still available. Shimano has also released its most affordable road wheelset, the $200 WH-RS21 wheelset that will be both 10 and 11 speed compatible.