With steep rises, loose surfaces, narrow trails and wide open roads, gravel riding often blurs the line between road and mountain biking. Long hours in the saddle sap strength from the legs and, in some cases, stomping on the pedals to crest a rise isn’t in the cards. A versatile bike setup, with gearing that suits you and your terrain, helps ensure that you can enjoy the fun that gravel riding has to offer whether that’s a day on the plains or in the depths of the mountains.
Shimano considered several things when designing its new GRX groupsets. The first is that gravel roads are slower by nature. The increased rolling resistance of the dirt and rock surface requires more work to maintain a given speed.
Secondly, because of the rough nature of gravel roads, wider tires are used. These larger tires increase comfort and control and help avoid punctures. But a larger overall wheel and tire size means that you travel farther with each revolution of the wheel. This also means that your gearing is effectively harder.
To accommodate for the lower speed and larger tires of gravel, Shimano GRX provides lower gearing and options for riders with different preferences.
With single and double front chainring options, Shimano GRX drivetrains create the climbing gear ratios below 1:1.
Lowest gears by GRX range:
· RX800-2 – 48/31T chainrings used with 11-34T 11-spd cassette
· RX800-1 – 40T chainring used with 11-42T 11-spd cassette
· RX600-2 – 46/30T chainrings used with 11-34T 11-spd cassette
· RX600-1 – 40T chainring with 11-42T 11-spd cassette
· RX400-2 – 46/30T chainrings with 11-36T 10-speed cassette
To put these numbers into real world terms, let’s take three examples and compare. Imagine a tough climb where you can maintain six miles per hour:
With a road compact crank with 50/34T rings and an 11-28 cassette on a gravel bike with 700c x 40mm tires, you would be climbing at a tough 60 rpm in your lowest gear.
In the same scenario (6mph, 40mm tire), using the lowest gear on offer with a Shimano GRX RX800-1 40T chainring and 11-42T cassette, you would ease the strain on your knees with a cadence of 77 rpm.
A GRX RX800-2 drivetrain (48/31T and 11/34T) would help even more. You would climb at a much more comfortable 80 rpm. That’s a 20-rpm difference that allows you to control your effort more precisely when tackling gravel terrain.
Gearing is as personal a choice as what saddle to ride. But this choice can make the difference between a struggle fest ride or a fun-filled day of exploration and self-discovery.
Ultimately, gravel gearing is a highly personal decision. Shimano encourages every rider to examine how best to achieve a wide enough gear range that also maintains the gear steps necessary to ride efficiently. Gravel riding is an adventure. Ensure that you have the right tools before you head out on your next gravel expedition.