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- GRX RX825 Di2 is Shimano's first wireless electronic gravel groupset — same BT-DN300 battery and E-TUBE app as road Di2. The FD auto-trims; the RD shifts under load via HYPERGLIDE+
- 1x vs 2x: RX822-SGS rear derailleur handles a 10-51T cassette for 510% range. GRX chainline is 2.5 mm wider than road for tire clearance up to 50 mm
- Gravel-specific ergonomics: taller, textured hoods with a front lip to anchor your hands on descents. The left lever (RX820-LA) doubles as a dropper-post remote — cable-actuated, no battery needed
- Cross-compatibility goldmine: GRX 12-speed chains (CN-M8100), cassettes (CS-M7100), and rotors (RT-MT800) are standard Deore XT MTB parts — buy them anywhere. GRX Di2 levers mix with Ultegra/105 Di2 derailleurs over the same wires and battery
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Why this page exists
Shimano's GRX family is the only groupset built from scratch for gravel — not a road groupset with wider gears, but a dedicated product line with its own lever ergonomics, clutch derailleurs, wider chainline, and dropper-post integration. Since its 2019 launch and the 2024 RX825 Di2 update, it covers every gravel build from a $1,500 alloy bike to a $10,000 carbon race machine.
This reference covers every current GRX tier — Di2, 12-speed mechanical, budget 12-speed, and the 10-speed entry point — with part numbers, real weights, and compatibility notes in one place.
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GRX tiers at a glance
Current GRX tiers, 2024–25. All 12-speed cassettes and chains are shared with Shimano MTB (Deore XT/SLX).
| Tier | Speeds | Shifting | Chainring options | Cassette range (max) | Weight | Price tier |
|---|---|---|---|---|---|---|
| RX825 Di2 (Ultegra-level) | 12 | Wireless electronic | 1x: 40T / 2x: 48-31T | 1x: 10-51T / 2x: 11-36T | ≈2,750 g (1x) | $$$$ |
| RX820 (105/Ultegra) | 12 | Mechanical | 1x: 40T–42T / 2x: 48-31T | 1x: 10-51T / 2x: 11-36T | ≈3,000 g (1x) | $$$ |
| RX610 (budget 12s) | 12 | Mechanical | 1x: 40T / 2x: 46-30T | 1x: 10-51T / 2x: 11-36T | ≈3,200 g (1x) | $$ |
| RX400 (entry 10s) | 10 | Mechanical | 2x: 46-30T only | 2x: 11-36T (10s) | ≈3,500 g (2x) | $ |
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Shifters and levers — gravel ergonomics
GRX levers are visibly different from road equivalents: the hood body is taller, wider, and more textured, with a pronounced lip at the front that keeps your hands planted on rough descents. The brake lever blade has a flatter profile and a shorter reach for confident one-finger braking from the hoods.
The standout piece is the ST-RX820-LA — a left-side mechanical lever that doubles as a dropper-post remote. It uses a second cable port routed through the lever body; you operate it by pulling the inner brake lever blade sideways. No battery, no electronics — purely mechanical, and compatible with any cable-actuated dropper.
RX825 Di2 levers are fully wireless (2×CR1632 coin cells) and connect to the same E-TUBE app as Ultegra/105 Di2. You can pair GRX Di2 levers with road Di2 derailleurs — run a GRX lever + Ultegra RD on the same bike over EW-SD300 wires.
All current GRX STI levers. LA suffix = dropper-post lever variant.
| Model | Speeds | Shifting | Weight (each) | Key feature |
|---|---|---|---|---|
| ST-RX825 (L/R pair) | 2×12 | Di2 wireless | ≈190 g | Wireless, E-TUBE app, mixed-groupset pairing |
| ST-RX820 (L/R) | 2×12 | Mechanical | ≈265 g | Servo Wave brake linkage |
| ST-RX820-LA (L) | 1×12 | Mechanical | ≈275 g | Built-in dropper-post lever |
| ST-RX610 (L/R) | 2×12 | Mechanical | ≈280 g | 105-level internals, same ergonomics |
| ST-RX400 (L/R) | 2×10 | Mechanical | ≈305 g | Budget entry, GRX hood shape |
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Rear derailleurs — clutch, capacity, and the 1x beast
All GRX rear derailleurs include Shimano's chain stabilizer (clutch) with an on/off switch. The clutch tension is tuned lighter than MTB — enough to stop chain slap on corrugations without adding noticeable shift effort. The Di2 derailleur (RD-RX825) shifts under full load using HYPERGLIDE+ ramps.
Derailleur choice defines gearing: RX822-SGS (mechanical long cage) swallows a 10-51T cassette for 1x, while RX825/RX820/RX610 medium-cage derailleurs cap at 36T for 2x. For 1x Di2 with a 10-51T, pair the GRX Di2 lever with an XT Di2 RD-M8150 — one of GRX's most useful cross-compatibility tricks.
GRX rear derailleur specs. All models have chain stabilizer (clutch) with on/off switch.
| Model | Speeds | Shifting | Cage | Max low sprocket | Capacity | Weight |
|---|---|---|---|---|---|---|
| RD-RX825 | 12 | Di2 | Medium (GS) | 36T | 37T | ≈310 g |
| RD-RX820 | 12 | Mechanical | Medium (GS) | 36T | 37T | ≈290 g |
| RD-RX822-SGS | 12 | Mechanical | Long (SGS) | 51T | 41T | ≈305 g |
| RD-RX610 | 12 | Mechanical | Medium (GS) | 36T | 37T | ≈310 g |
| RD-RX400 | 10 | Mechanical | Medium (GS) | 36T | 37T | ≈315 g |
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Front derailleurs — Di2 auto-trim, wider chainline
GRX front derailleurs are designed for a +2.5 mm wider chainline than road (47 mm vs 44.5 mm) — critical for 45 mm+ tire clearance. The RX825 Di2 FD auto-trims: as the rear derailleur moves across the cassette, the FD micro-adjusts to eliminate chain rub, same technology as Dura-Ace Di2 FD.
GRX front derailleurs. All are braze-on mount with an included band-clamp adapter (31.8/34.9 mm).
| Model | Speeds | Shifting | Chainline | Max chainring | Capacity | Weight |
|---|---|---|---|---|---|---|
| FD-RX825 | 2×12 | Di2, auto-trim | 47 mm | 48T | 17T | ≈130 g |
| FD-RX820 | 2×12 | Mechanical | 47 mm | 48T | 17T | ≈95 g |
| FD-RX610 | 2×12 | Mechanical | 47 mm | 46T | 16T | ≈100 g |
| FD-RX400 | 2×10 | Mechanical | 47 mm | 46T | 16T | ≈105 g |
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Cranksets — 1x and 2x, HOLLOWTECH II
GRX cranks use the 24 mm HOLLOWTECH II spindle common to all Shimano road cranks. The Q-factor is 151 mm (+2.5 mm vs road) — barely noticeable underfoot but it provides frame clearance. Chainrings are direct-mount (4-bolt 110/80 BCD on 2x). Aftermarket rings from Wolf Tooth (36T–38T 1x) are plug-and-play on the 1x cranks.
GRX cranksets. All use 24 mm spindle and HOLLOWTECH II bottom brackets (threaded BSA or press-fit). Lengths: 170, 172.5, 175 mm.
| Model | Speeds | Chainrings | Q-factor | Weight (172.5 mm) | Note |
|---|---|---|---|---|---|
| FC-RX820-1 | 1×12 | 40T (also 42T) | 151 mm | ≈655 g | DYNAMIC CHAIN ENGAGEMENT+ chainring |
| FC-RX820-2 | 2×12 | 48-31T | 151 mm | ≈720 g | HOLLOWTECH II, forged |
| FC-RX610-1 | 1×12 | 40T | 151 mm | ≈720 g | Standard forging, heavier |
| FC-RX610-2 | 2×12 | 46-30T | 151 mm | ≈780 g | Budget 2x, smaller rings |
| FC-RX400-2 | 2×10 | 46-30T | 151 mm | ≈815 g | Entry-level, non-HOLLOWTECH |
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Cassettes and chains — off the MTB shelf
GRX 12-speed cassettes are Deore XT/SLX MTB parts: the CS-M7100-12 in 10-45T (≈380 g) is the go-to 2x cassette. For 1x, the 10-51T CS-M7100-12 (≈470 g) gives 510% range. Chains are CN-M8100 (XT, QuickLink, SIL-TEC coating, ≈255 g) or CN-M6100 (Deore, ≈275 g).
Important: GRX 12-speed cassettes require a MICRO SPLINE freehub body. If your wheels have a standard HG freehub, you cannot run GRX 12-speed without a new freehub or different wheels. Many gravel wheels now ship with MICRO SPLINE for this reason.
RX400 (10-speed) uses the CS-HG500-10 cassette (11-32/34/36T) on a standard HG freehub — no freehub change needed.
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Brakes and rotors
GRX calipers are flat-mount, two-piston, mineral oil. The BR-RX820 uses ICE TECH radiator fins and accepts metal pads (K03S/K04S) for wet conditions. Rotors are MTB parts: the RT-MT800 (ICE TECH FREEZA, centerlock) is the recommended pairing. All GRX calipers accept 140 or 160 mm rotors front and rear, no adapters needed for flat-mount frames.
GRX brake components. All use mineral oil. Pads are shared across the whole Shimano road+gravel ecosystem.
| Model | Pad type | Weight (front) | Rotors (recommended) |
|---|---|---|---|
| BR-RX820 | K05S-RX resin (K03S metal optional) | ≈130 g | RT-MT800: 140 mm (≈114 g) / 160 mm (≈133 g) |
| BR-RX400 | B05S-RX resin only | ≈145 g | RT-70 or RT-MT800 (140/160 mm) |
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GRX wheels — WH-RX880 carbon
Shimano's factory GRX carbon wheelset (WH-RX880-TL): 32 mm rim depth, 25 mm internal width (fits 32–50 mm tires), CENTER LOCK rotors, MICRO SPLINE freehub. Actual weight: ≈1,460 g/set (verified). Tubeless-only, hookless rim — do not use clincher tires. Competitive with Zipp 303 Firecrest (1,408 g) at roughly half the price.
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Cross-compatibility — the GRX superpower
Because GRX borrows from both road and MTB catalogs, the mixing potential is excellent. Confirmed cross-compatible mixes (per Shimano compatibility charts and third-party testing):
• GRX Di2 levers + Ultegra/105 Di2 derailleurs: works. Same battery (BT-DN300), same wires (EW-SD300), same E-TUBE app.
• GRX Di2 levers + XT Di2 RD-M8150 (MTB, 51T range): works. This is how you build a 1x Di2 GRX bike with a 10-51T cassette — use a GRX 1x crank, XT Di2 RD, and GRX Di2 levers together.
• Road cranks on a GRX bike: mechanically fits but the 2.5 mm narrower chainline limits tire clearance; not recommended for tires over 40 mm.
• GRX 2x cranks + road FD + road shifters: works. The GRX wider chainline is within the road FD's lateral adjustment range.
• Chains, cassettes, and rotors are standard MTB parts — no GRX tax.
• RX400 (10-speed) does NOT mix with 12-speed GRX — different cable pull ratios, different freehub (HG vs MICRO SPLINE).
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Which GRX tier to pick
RX825 Di2: if you race gravel or want shift speed that matches Dura-Ace. The mixed pairing potential (XT Di2 RD + GRX Di2 lever for 1x) is this tier's unique value.
RX820 (12s mechanical): the value sweet spot. Same gear range as Di2, same clutch derailleur, same crank options — without the electronics. The RX822-SGS long-cage for 1x gives you 510% range for roughly 2/3 the Di2 price.
RX610 (12s mechanical): budget 12-speed. Heavier cranks, no dropper-post lever, smaller chainrings — but the shifting feel is close to RX820 and the MICRO SPLINE cassette options are the same.
RX400 (10s): entry-level gravel for rail-trails and fire roads, not racing. The 10-speed HG ecosystem is totally fine, widely available, and it's the cheapest way to get genuine GRX lever ergonomics.
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Maintenance notes
• Clutch service: the GRX chain stabilizer is self-adjusting but benefits from a clean-and-regrease every 2,000–3,000 km. The on/off switch can stiffen with dried mud — a drop of oil on the pivot restores it.
• Di2 battery (BT-DN300): fits in the seatpost (27.2+ internal routing) or bar-end. Charge via the USB-C port on the rear derailleur; one charge lasts ≈1,000 km. Check levels in the E-TUBE app.
• Brake pads: K05S-RX resin pads (≈$25/pair) last 1,500–2,000 km on mixed surfaces. Metal pads (K03S) add wet-weather bite but increase rotor wear.
• Chain replacement: measure with a TL-CN42 chain wear tool. At 0.5% elongation, replace the chain to protect the cassette. The CN-M8100 QuickLink is reusable up to 3 times per Shimano.
• MICRO SPLINE lockring: 40 N·m torque — use a torque wrench. The TL-LR15 cassette tool engages the splines; stripping the aluminum freehub threads is an expensive mistake.
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