Although SRAM, Shimano and Campagnolo’s interpretations of a clutch derailleur differ slightly, they all aim to achieve the same thing.

Deore XT rear derailleur delivers reliable and precise shifting with a stiff and lightweight open designand 9-speed SRAM components are all inter-compatible, regardless of whether they are road or mountain bike parts There are also differences in the pull ratios used between different groupsets: the Ergopower shifters used by mechanical Super Record, Record and Chorus 11-speed are not compatible with Potenza, which itself is incompatible with both Ergopower and Centaur Power-Shift systems. Campagnolo’s Super Record EPS electronic groupset is on version four now and has gone 12-speed. Again, it’s a system unto itself, with its own electronics to communicate between the shifters and the rear derailleur. Dura-Ace 7970 and Ultegra 6770 Di2 10-speed components are not compatible with each other. This is because they use different wires, with the Ultegra variant using the SD50 type that would go onto be used on 11-speed.

Now that we’ve gone through the tortuous process of working out exactly what will work with your drivetrain, you have the fun of deciding which price point to go for. The granting of a best price is not combinable with other promotions (e.g. "free articles) from Bike-Discount. Almost all modern mountain bike derailleurs (and Shimano’s GRX gravel groupsets, Ultegra RX rear derailleur, Campagnolo Ekar, SRAM’s single-ring road groupsets and eTap AXS 12-speed road rear derailleurs) include a clutch mechanism. Chain reaction Cycles and CRC are trading names of Wiggle Ltd (In Administration) registered in the United Kingdom at 1000 Lakeside, Suite 310, Third Floor N E Wing, Portsmouth, Hampshire, PO6 3EN, This is also the case with Shimano’s 11-speed mountain bike components – for example, you could use an XTR M9000 derailleur with a pair of SLX M7000 shiftersIf you are running a 1x drivetrain with a regular-sized cassette (ie, 11-36t or smaller) or some 2x mountain bike drivetrains with a similarly sized cassette, you may want to use a medium cage derailleur. The situation is a little more clear with SRAM and we’ve summarised the main points below. SRAM road and gravel derailleur compatibility All 11-speed Shimano Di2 road, gravel and mountain bike Di2 components are inter-compatible – you could, for example, use an XT M8050 rear derailleur with a pair of Ultegra R8070 shifters

Compatible parts are now marked by a letter surrounded by a square box – simply put, if all of your components have the same stamped letter on them, they’ll work together. Regular rear derailleurs rely solely on the tension provided by the main pivot to keep the chain in place. SRAM’s latest 12-speed eTap AXS road and MTB groupsets can be used together, setting up the option for ‘mullet builds’, which pair up road shifters with an Eagle AXS rear derailleur and a 10-50 cassette, for an ultra-wide gravel bike build. There are two common situations where there may be a large range, or spread, of gears on your bike – when using a super-wide range cassette (eg, 10-42t or larger) or when there is a large difference between chainring sizes (eg, when using a triple chainset).

Top normal spring uses the spring to select higher gears, best suited to use with Rapidfire shifters A clutch derailleur essentially increases the resistance this pivot provides – either through a clutch or more complex electro-hydraulic systems, as seen on SRAM AXS – resisting fore and aft movement of the derailleur cage, and making for a far quieter and more reliable drivetrain. SRAM’s current 12-speed eTap AXS rear derailleurs are all compatible across road, gravel and mountain biking. For example, you can run an Eagle rear derailleur on a road or gravel bike. If you’re doing this, you’ll need to run a compatible chain (you cannot run a road FlatTop chain with an Eagle rear derailleur), chainring and cassette All 12-speed Shimano mountain bike components are inter-compatible – you could, for example, use an SLX M7120 derailleur with an XTR M9100 trigger shifter