SHIMANO GRX Di2 825 groupset 2x12 | crank 175 mm cassette 11-34
With the GRX, Shimano launched the first gravel-specific groupset on the market. Since then, the range of applications and the range of gravel bikes has expanded significantly. Shimano has responded to this development by updating the GRX groupset. It now comes with modern Di2 technology and a 12-speed drivetrain. The high level of functionality and quality reflects the Japanese company's many years of experience.
Technically, the GRX Di2 is similar to the current road bike groupsets. The shifting commands are transmitted wirelessly to the front derailleur and rear derailleur. The latter are connected to a central battery, which can be concealed in the seat post, for example. The 12-speed drivetrain has also been adopted and enables a wider gear range. This makes long uphill rides very comfortable even for less trained riders.
Shifter/brake lever SHIMANO GRX Di2 ST-RX825 + brake caliper BR-RX820 Flat Mount
The GRX shift/brake levers have a grip geometry and surface texture specially optimized for gravel use. The upper hump has been raised to prevent you from slipping forwards on rough surfaces, and the shape has been optimized for wide-spread use.And to prevent your hands from sliding back and forth even when riding in the rain, a non-slip material has been selected which also has good damping properties and therefore increases comfort.
Shifting is done at the touch of a button. This is quick and effortless. The pressure point is so precise that unintentional gear changes are practically impossible. This wireless system is also fully customizable with the help of the Shimano E-Tube app. Among other things, the shifting speed can be set, a fully or semi-synchronous shifting mode can be selected and the program buttons on the lever can be assigned specific functions. Energy consumption is also very low. According to Shimano, the two CR1632 button cells should supply the electronics with power for over 3 years. The absence of wiring not only simplifies installation, but also gives you a neat and tidy cockpit.
The brake lever has also been designed so that you can stop quickly at any time from any grip position. It is slightly bent inwards and the axis of the lever has been moved upwards. This improves the ergonomics and at the same time reduces the necessary manual force. In addition, the reach of the brake lever can be individually adjusted so that bikers with smaller hands can also ride safely.
The flat-mount brake calliper improves braking performance and modulation under all conditions. Maintenance work, such as bleeding or changing pads, is also easy to carry out. The L03A brake pads with cooling fins help to keep braking temperatures low, especially on long descents.
Brake rotor SHIMANO Ultegra Center Lock RT-CL800 | 160 mm + 160 mm
When developing the Ultegra CL800 brake rotors, Shimano engineers succeeded in preventing heat-related deformation of the rotors. As a result, they offer more reliable, more controllable braking performance and are quieter than ever before. Fortunately, the weight has remained at the same low level as the previous version.
Also on board is Shimano's Ice-Tech cooling technology, which ensures excellent heat dissipation and constant braking performance even on long, steep descents. The brake discs feature a three-layer sandwich construction with stainless steel sides and an aluminium core for significantly improved heat dissipation. This reduces the temperature by around 100 °C. In addition, the FREEZA aluminum cooling fins reduce the system temperature by around a further 50 °C thanks to their increased surface area. The increased heat dissipation means that smaller brake discs can be fitted than usual. The service life of the brake pad is also significantly extended.
As is typical for Shimano, the rotors are suitable for Center-Lock mounts, which enable quick and easy installation, provide a secure hold and ensure a clean and compact look.
Crank SHIMANO GRX FC-RX820-2 | 2x12-speed | 48/31 teeth | Q-factor 151 mm | crank arm length 175 mm
The FC-RX820 crankset comes with a typical gravel gradation. With the large 48-tooth chainring, you can make good speed on flat terrain, but can also climb longer ascents with ease with the small 31-tooth chainring. The chainline has been shifted outwards to make room in the frame for wider tires. Nevertheless, the Q-factor has remained pleasantly narrow at 151 mm. The typically excellent Shimano workmanship and aerodynamically shaped elements on the outer chainring make the crankset a long-lasting and reliable companion on your tours.
Front derailleur SHIMANO GRX Di2 FD-RX825 | 2x12-speed
The advantage of electronic shifting systems is particularly noticeable with the front derailleur. At the touch of a button, the chain moves from one chainring to the other as if by magic, without any effort at all. It also thinks for itself and automatically adjusts its position to the chain skew to avoid grinding noises. With the help of the Shimano E-Tube app, the front derailleur is adjusted after installation and a manual, fully or semi-synchronous shifting mode is selected depending on preference.
The GRX front derailleur has been designed to suit the wider tires of gravel bikes. Compared to Shimano Road front derailleurs, the chainline has been moved outwards by 2.5 mm to 46 mm. Designed for Shimano 12-speed chains and with its chainring capacity of 17 teeth, the front derailleur harmonizes perfectly with the GRX FC820-2 crank with 48-31 teeth.
Rear derailleur SHIMANO GRX Di2 RD-RX825 Shadow+ | 2x12-speed
The RX825 Di2 rear derailleur was specially developed for the 2x12 GRX drivetrain and cassettes with 11-34 or 11-36 teeth for Shimano Road freehub bodies. With this you have a very wide range and at the same time a very finely graduated gear ratio on board.
Thanks to the built-in Shadow RD+ chain stabilizer, the chain remains securely on the chainring even on the roughest gravel trails.
What's more, gear changes have never been so quick. At the push of a button, the chain shifts from one sprocket to the other in a fraction of a second, regardless of the situation. This is carried out by the powerful and reliable integrated motor. The system is also supplied with new energy via the rear derailleur. The charging cable is plugged into the small charging port and after approx. 1.5 hours you can get back in the saddle. A small LED reliably indicates the remaining capacity. With the help of the Shimano E-Tube app, the rear derailleur is fine-tuned after installation and a manual, fully or semi-synchronous shifting mode is selected depending on preference. The narrow Shadow profile reduces the risk of damage in the event of a fall.
SHIMANO CS-HG710 cassette 12-speed | 11-34 teeth
The Shimano Hyperglide cassettes have set new standards in off-road use with their smooth upshifting and downshifting across the entire gear range. Shifting is now possible without hesitation, even when applying maximum force on climbs or sprinting to the finish line. Among other things, longer teeth make this possible. Despite the new design and the additional 12th sprocket, the cassette is also compatible with 11/12-speed Shimano Road freehub bodies.
SHIMANO Deore XT | Ultegra CN-M8100 12-speed chain | 126 links with chain lock
The CN-M8100 chain is specially designed for the M8100 chainrings and cassettes. Thanks to cut-outs on the inside of the plates, the chain harmonizes perfectly with the Dynamic Chain Engagement+ (DCE+) narrow-wide tooth profiles of the new XT chainrings. The design results in a tighter fit of the chain on the teeth. Vibrations are avoided and the smoother chain run is not only noticeable when pedaling, but is also noticeable acoustically thanks to a 4 dB quieter drivetrain. Thanks to a new chrome-plated surface in combination with the proven SIL-TEC coating, the service life of the chain has been kept at the same level as the M8000 chain, despite the smaller outer width.
BT-DN300 internal battery
Integrated battery of the latest generation, which is recessed in the seat post or steerer tube. The internally routed cables give the road bike a tidy appearance. The integration of the battery into the frame also reduces the number of attachments that stand in the wind. The battery is charged via a small socket on the rear derailleur and does not need to be removed.
E-Tube cable SHIMANO for Di2 | EW-SD300-I internal
These cables connect all electrical components of the Shimano E-Tube system. They are used in the current Dura Ace Di2 9200 and Ultegra 8100 groupsets, among others. The more compact design enables the use of smaller, lighter electronic components and makes internal cable routing much easier.
SHIMANO EW-EC300 charging cable
With this charging cable you can charge the battery of your Shimano 12-speed drivetrain via the charging port on the rear derailleur.
Technical data
Area of application: Gravel
Material: Aluminum, plastic
Gears: 2x12
Brake type: hydraulic disc brake
Brake mounting: Flatmount, optional adapter may be required depending on fork and frame
Crankshaft: 24 mm
Crank length: 175 mm
Chainring gradation: 48/31 teeth
Chainring mount: 4-arm asymmetrical | LK 110 / 80 mm
Cassette gradation: 11-34 teeth
Freehub body compatibility: Shimano Road
Color: black, grey, silver
Weight according to manufacturer: 2873g
Weight self-weighed:
Scope of delivery:
1x SHIMANO shift / brake lever GRX Di2 ST-RX825 + brake caliper BR-RX820 Flat Mount front
1x SHIMANO shift / brake lever GRX Di2 ST-RX825 + brake caliper BR-RX820 flat mount rear, WITHOUT flat mount adapter
2x SHIMANO brake rotor Ultegra Center Lock RT-CL800 | 160 mm
1x SHIMANO crank GRX FC-RX820-2 | 2x12-speed | 48/31 teeth | Q-factor 151 mm | crank arm length 175 mm
1x SHIMANO front derailleur GRX Di2 FD-RX825 | 2x12-speed
1x SHIMANO rear derailleur GRX Di2 RD-RX825 Shadow+ | 2x12-speed
1x SHIMANO cassette CS-HG710 12-speed | 11-34 teeth
1x SHIMANO chain Deore XT | Ultegra CN-M8100 12-speed | 126 links with chain lock
1x SHIMANO BT-DN300 internal battery
1x SHIMANO E-Tube cable for Di2 EW-SD300-I | 600 mm
1x SHIMANO E-Tube cable for Di2 EW-SD300-I | 1200 mm
1x SHIMANO charging cable EW-EC300
WITHOUT BOTTOM BRACKET
WITHOUT brake adapter
Notes:
Delivery without rear brake rotor adapter. Before installation, please check which disc size the mounts on your frame are designed for.
You can find the recommended bleeding kit and brake fluid for connecting the brakes in our store.
SHIMANO Professional Bleed Kit for Disc Brakes TL-BR001/TL-BR002/TL-BR003available from stock
SHIMANO Rubber Insert for internal Cable Routing from EW-SD5300 Cables | 1 pcsavailable from stock
ENVE Fork 28" All Road IN-Route Carbon | Tapered 1 1/2" | 12x100 mm Thru Axleavailable from stock