Regular rear derailleurs rely solely on the tension provided by the main pivot to keep the chain in place. Current 9-speed Shimano mountain bike components are compatible with older 9-speed road and mountain bike components, excluding the aforementioned exception With clutch derailleurs offering a quieter and more reliable drivetrain, there are few compelling reasons not to buy a clutch derailleur for a mountain bike. What do I get with a more expensive derailleur? Now we’ve determined the speed, brand and compatibility of your derailleur, you must work out the cage length that your drivetrain requires: long, short or medium.

However, SRAM’s Force AXS Wide groupset means you may not have to create your own mullet builds. Bridging the gap between road-going AXS groupsets and mullet builds, the groupset offers a lower bottom gear for road and a good range for gravel riding with cassettes up to 36 teeth, but does this by altering the drivetrain alignment.

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.

and 9-speed SRAM components are all inter-compatible, regardless of whether they are road or mountain bike parts Campagnolo has introduced many changes to its groupsets, resulting in reduced compatibility between generations. So boxed letters (indicating the ranges) will aid you in identifying if your parts are compatible. The front derailleur has been enhanced, too. Gone is the in-cable barrel adjuster, replaced instead with an integrated cable tension port. This is something introduced to Dura-Ace and Ultegra level models, which results in lighter shifting between the front chain rings. 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.It uses the traditional Shimano joining pin system (standard chain tools are suitable too), and we tried a variety of joining links including Powerlink, which all worked fine. 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 However, things get much easier with its latest 12-speed road groupsets. You can mix and match components between Chorus, Record and Super-Record. All 11-speed Shimano road components are inter-compatible – you could use a Dura-Ace R9100 derailleur with a pair of 105 R7000 shifters. This is also true of the brand’s 11-speed GRX components Shimano’s latest XT Di2 M8150 12-speed rear derailleurs are designed for electric mountain bikes and are not compatible with non-assisted bikes

speed SRAM components are inter-compatible, regardless of whether they are road or mountain bike parts – for example, you could run road shifters with a mountain bike rear derailleur 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. Campagnolo provides a much more thorough description of the changes and we highly recommend you read through this guide carefully before committing to any new parts from the Italian marque.Campagnolo’s Super Record EPS electronic groupset is now onto its fourth generation. Matthew Loveridge / Immediate Media Apart from first-generation Dura-Ace Di2, which uses a different wiring harness, the second (11-speed) generations are inter-compatible, across road, gravel and mountain bike groupsets as they all use the SD50 wires and share the same electronics.