Shimano Deore XT RD-M8150-12 Di2 Rear Derailleur — 12-Speed SGS Long Cage
IRDM815012SGS
SKU code: SHM-IRDM815012SGS
In Stock
The Shimano Deore XT RD-M8150-12 is a 12-speed electronic rear derailleur purpose-built for e-MTB use, delivering precise, rapid shifting under the higher chain loads that electric mountain bikes generate. Powered directly by the STEPS battery via E-TUBE cabling, it integrates seamlessly into the Shimano STEPS ecosystem for intelligent, motor-aware gear management.
Highlights
- FREE SHIFT technology lets you change gears while coasting — ideal for tight switchbacks and technical descents
- Shadow Plus chain stabiliser reduces chain slap and sway on rough terrain without sacrificing shift feel
- Di2 electronic shifting for fast, precise, one-touch gear changes under load
- HYPERGLIDE+ compatibility for smooth shifting in any direction, even under pedalling pressure
- SGS long cage handles up to 51T low sprocket for wide-range e-MTB gearing
- Sealed bearings on both guide and tension pulleys for long-term reliability in trail conditions
- E-TUBE PROJECT app compatible for firmware updates, diagnostics, and personalised shift settings
E-MTB Optimised Engineering
Conventional derailleurs are not designed for the additional chain tension and torque spikes generated by electric motor assistance. The RD-M8150-12 is engineered from the ground up for STEPS e-bike systems — its internals handle heavier chain loads without compromising shift speed or accuracy. The integrated Shadow Plus design keeps the chain firmly on the cassette across broken ground, functioning as a lightweight chain-management solution without the bulk of a dedicated roller-type chain device.
FREE SHIFT & Auto Shift
FREE SHIFT allows the rider to select a new gear at any time — including while completely coasting — so you can set up the optimal gear before driving out of a corner or powering up a steep climb. Combined with the STEPS Auto Shift function, which analyses speed, cadence, and motor output to recommend gear changes, the RD-M8150-12 can significantly reduce rider fatigue on long technical climbs and descents.
Compatibility & Fit
The RD-M8150-12 is exclusively compatible with Shimano STEPS EP801 and EP600 motor systems — it cannot be used on non-electric bicycles or with other motor platforms. It requires a direct-attachment rear derailleur hanger and connects to the STEPS system via an EW-SD300 E-TUBE cable (sold separately). Compatible cassettes include the CS-M9101-12, CS-M9100-12, CS-M8100-12, CS-M7100-12, and CS-M6100-12 (11–51T range). Use with Shimano 12-speed chains (CN-M9100, CN-M8100, CN-M7100, or CN-M6100). Minimum 10T top sprocket; maximum 51T low sprocket; total capacity 41T.
Shimano warrants this product against defects in materials and workmanship for two years from the date of original retail purchase. This warranty covers manufacturing defects and does not extend to damage caused by crash, misuse, improper installation, or normal wear and tear. For warranty support, return the item to Tune Cycles.
- 12-speed Di2 electronic shifting
- SGS long cage — 51T maximum low sprocket
- FREE SHIFT: shift gears while coasting
- Shadow Plus integrated chain stabiliser
- HYPERGLIDE+ drivetrain compatible
- Powered via STEPS battery — no separate battery required
- E-TUBE PROJECT app compatible
- Sealed bearings on guide and tension pulleys
- 13-tooth pulley wheels
- Direct-attachment hanger mount
- Compatible with Shimano STEPS EP801 and EP600 motor systems only
| Specification | Value |
|---|---|
| Speeds | 12 |
| Cage Length | SGS (Long) |
| Weight | 375 g |
| Total Capacity | 41T |
| Max Low Sprocket | 51T |
| Min Top Sprocket | 10T |
| Pulley Teeth | 13T |
| Shifting Type | Electronic (Di2) |
| Chain Stabiliser | Shadow Plus |
| Mount Type | Direct attachment |
| Pulley Bearings | Sealed |
| Motor Compatibility | Shimano STEPS EP801 & EP600 only |
| Cable Connection | EW-SD300 E-TUBE (sold separately) |
| Colour | Black |
| SKU | SHM-IRDM815012SGS |
| Barcode # | 4550170239626 |
| Brand | Shimano |
