Keen eyes may have noticed a new Shimano rear derailleur on John Degenkolb’s Tour of Flanders bike. It’s a clutch-style Ultegra rear derailleur called the Ultegra RD-RX800/RX805 (mechanical and Di2, respectively). Akin to Shimano’s mountain bike rear derailleurs, the clutch improves chain security on single- and double-chainring drivetrains.
This looks like a response to the burgeoning gravel scene, in which chain retention on both 1X and 2X drivetrains is increasingly important. While it’s less important on a 2X setup, where there’s a small chainring to catch a loose chain, the idea is to prevent chain drops altogether.
The flipside of that benefit, however, is increased pressure required to shift the rear derailleur, since you’ll be fighting both spring tension in the derailleur and clutch tension. Of course, that matters far less on the Di2 version. There’s an on/off switch to control the stabilizer mechanism, too.
The new Ultegra derailleur is compatible with all current road Dual Control levers from Shimano and will work with 11-28 to 11-34 tooth cassettes. The mechanical version costs $110, and the Di2 version will run $285.
Discs and better ergonomics for 105
Shimano’s workhorse 105 group set also gets the trickle-down treatment, not to mention a makeover to match its higher-end brethren. The addition of disc brakes to the lineup is perhaps the biggest news, but there are other refinements that are cause for excitement.
Notably, the brake lever hood ergonomics have been streamlined to better match the shape and feel of Ultegra levers. This is especially obvious on the hydraulic levers. And Shimano now offers a “small hand” shifter option. The reach starts 4mm closer than the regular brake levers, and the lever blades are designed to prevent riders from rotating their hands to grab the levers.
Other highlights include the addition of an 11-34 cassette and RD-R700-GS derailleur to match.The SM-RT70 rotors will also be available in a 140-millimeter option. The crankset offers additional versatility with the introduction of a 160-millimeter length option.