Shimano has launched a new groupset called the GRX that’s aimed specifically at the gravel bike segment, which can be configured as either a 1x, 2x, 10 or 11-speed set-up and is available in both mechanical and electronic variants. Moreover, the Japanese component giant has added integrated dropper seatpost capabilities to the new drivetrain as well, which includes three tiers, the RX400, RX600 and RX800.
In the case of the 1X crankset, it’s available in both a 40T or 42T chainring, while the 2x version is offered in either a 48/31t or 46/30t option.
Both feature Shimano’s Dynamic Chain Engagement tooth-profile for increased chain retention over rough terrain.
According to Shimano, the GRX front derailleurs are designed to move the chainline out by 2.5mm in order to accommodate tires up to 42mm in the rear, while the GRX RX800 series front derailleur (both mechanical and electronic) is compatible with chainrings up to a super-wide 48/31.
The RX400 derailleurs are meant to work with the smaller 16-tooth gap.
The GRX rear derailleurs are available in two Di2 and three mechanical versions, and utilize the same on/off clutch design as last year’s Ultegra RX, along with Shimano’s chain stabilizing system called SHADOW RD+ that’s deigned to reduce chain slap over harsh terrain.
However, the RD-RX815 (Di2) and RD-RX810 rear derailleurs (short cage) can be used with Ultegra, 105 or Tiagra 11-30/34 cassettes, while RD-RX817 (Di2) and RD-RX812 rear derailleurs (long cage) can accommodate Deore XT, SLX or Deore 11-40/42 cassettes.
The GRX levers now feature gravel-specific ergonomics, raising the axis point by 18mm, along with a new curved brake lever profile and an anti-slip textured finish to offer superior grip over rough ground.
Additionally, when using the ST-RX810-LA levers with a 1×11 drivetrain setup, Shimano says the left lever can be configured to control a dropper seatpost directly.
Not surprisingly, the GRX groupsets are hydraulic disc brake only and comprise Shimano’s flat-mount and ICE braking technologies, with the top tier ST-RX811 series featuring the brand’s Servo Wave technology as found on their MTB brake systems.
As for the non-Servo Wave brakes in the GRX line-up, Shimano says they have stopping power that’s on par with Ultegra, 105 or Tiagra disc brakes.
There’s also an inline brake lever that’s available, which can be fitted to the handlebar that’s often used in cyclecross racing or on extra-rough terrain like cobbled roads.
No groupset from Shimano would be complete without a dedicated wheelset. In which case, there are two variants being offered, a 700c or 650b that weigh in at a claimed weight of 1,600g and 1540 respectively.
Both wheelsets are tubeless ready as well.
The Shimano GRX mechanical groupsets are expected to go on sale in August, with pricing to be announced, while the launch date for the electronic series is yet to be announced.
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