What is a mullet train? Plus how to match MTB derailleurs and shifters

Microshift Advent X Gravel

A mullet drivetrain pairs drop-bar shifters with a wide mountain bike rear derailleur, usually set to 1x.

Mullet drivetrains offer the range of mountain bike groups while providing drop-bar comfort for long days in the saddle. They are most often found in gravel bikes.

Mullet drivetrains have been on the cutting edge of gravel technology for years, with few officially certified setups offered by mainstream brands.

However, many manufacturers now offer officially compatible mullet mounts, with some bike manufacturers specifying them as stock.

In this article, we will explain what a mullet drivetrain is, how they work, what kind of bike you can find them on and explain compatibility issues.

What is a mullet train?

Microshift Advent X Gravel

Mullet rails are increasingly popular on gravel bikes.

In its simplest form, a mullet train is a hybrid group that pairs a road bike derailleur with a mountain bike derailleur and a wide cassette.

Mountain bike derailleurs are compatible with the largest cassettes. Many are still stronger than road bikes or gravel bikes.

They are increasingly popular as an aftermarket or custom upgrade because they offer the same range (if not greater) as a 2x setup, but with the simplicity of a 1x drivetrain while keeping the handlebars lowered for a variety of long riding positions.

How does the mullet train work?

The Sram Apex Eagle groupset is in action

Mullet drivetrains provide the widest range possible for a 1x gravel bike.

A mullet train works in the same way as a regular road/gravel drivetrain or mountain bike, but only if the pull ratio of the road shifters and mountain bike derailleurs are the same.

SRAM and Shimano use different ratios for mechanical mountain bikes and road bikes. This makes combining components across disciplines impossible without upgrades or adapter kits.

The XT Di2 derailleur comes in a single cage length and works with 1x and 2x drivetrains

Although rarely seen, it is possible to match mountain bike components 11 speed Shimano Di2 with 11 speed Di2 bicycle.
Josh Patterson / Our Media

The situation is simpler with electron groups. SRAM AXS derailleurs and shifters will talk to each other regardless of whether they are road, gravel or mountain bike components.

There is also very limited compatibility between Shimano Di2 road, gravel and mountain bike groupsets (full compatibility is listed on Shimano’s website).

The mechanical mullet train can also be configured using a bar-end shifter, with Microshift providing a compatible shifter for Shimano drivetrains.

Microshift 10-speed bar-end shifters on Fuji Touring Disc bikes

Bar shifters are rarely seen these days, but they work well.
David Caudery / Immediate Media

End-bar shifters are less practical than plate-mounted shifters and can cause knee clogging in some cases. However, they are very strong, which makes them a popular choice for tough touring bikes and road bikes.

Wolf Tooth Tanpan

Pull-bar ratio shifters allow you to pair drop-bar shifters with mountain bike derailleurs.
Wolf teeth

A pull ratio shifter, such as Wolf Tooth Tanpan or Jtek Shiftmate can be used to match components that are not compatible with each other. That means weirder gearing – like pairing SRAM shifters with Shimano derailleurs – can be used.

Which bike uses a mullet setup?

3T Exploro with SRAM Mullet Drivetrain

Mullet rails are becoming a common sight on gravel bikes

Mullet setups are most common on mountain bikes, where the ergonomics of the handlebar go down well with a wide range of mountain bike drivetrains.

Bikes like 3T’s Exploro Ultra and Moots’ Routt ESC can be specced with mullet drivetrains, both in the form of SRAM’s AXS group.

Some touring bikes will also have mullet drivetrains as this allows for an easier setup with fewer components to fail, while still providing a gear range that allows you to hit the hills on a more loaded bike.

What about the gravel group?

Pinnacle Arkose X stone bike

Road bikes don’t offer the same range as found on mountain bikes.
Russell Burton / Our Media

While, strictly speaking, mullet rails should cover both road and mountain bike components, many manufacturers now produce 1x gravel groupsets that almost match the level of a true mullet setup.

However, the gear range is still less than mountain bikes and cassette combos, which often have cambers north of 50 teeth.

Mullet drivetrains by manufacturer

SRAM mullet drivetrains explained

SRAM Mullet Drivetrain

SRAM has adopted a mullet drive.

SRAM has fully embraced the mullet drivetrain with its AXS range.

The AXS shifter can be paired with any AXS Eagle rear derailleur.

Sram Apex Eagle kit

SRAM Apex Eagle levers are the first from the brand to use the X Actuation pull ratio.
Warren Rossiter / Our Media

In its mechanical group, SRAM uses two different cable pull ratios, with the Actuation used on road bikes and the X Actuation used on the brand’s 1x mountain bikes, making the two incompatible without modification.

However, the new mechanical SRAM Apex Eagle levers use the X Actuation pull ratio, making them compatible with all Eagle drivetrains.

Shimano mullet drivetrains explained

Shimano Cues U8000 (1 of 8)

Shimano Cues could be the brand’s first bus.
Jack Luke / Our Media

Like SRAM, Shimano uses different cable pull ratios in the road and mountain bike groups. This means that it is difficult to combine components without a third-party cable pull ratio adjuster.

Its Di2 group can be set in the direction of the mullet, but this time the solution is more reliable than the advertised features.

Shimano’s new Cues drivetrain holds promise for future mullet shifting, with every shifter in the new range using the same pull ratio.

The Tiagra has yet to fall into the Cues range, meaning dropouts are currently unavailable, although hopefully we’ll see a cheap mullet setup from Shimano soon.

Microshift mullet drivetrains explained

Microshift Advent derailleur

Microshift has a mullet option for all of its drivetrains.

Microshift is unusual in that the same pull ratio is used on both the road and mountain bike groupset, allowing for a high degree of compatibility.

The brand’s Advent and Advent X ranges allow you to combine a clutched rear derailleur with a maximum cog size of 46-tooth and a drop-bar shifter, although this limits you to disc brakes.

Microshift also makes a variety of bar-end shifters that are compatible with Shimano and SRAM drivetrains, allowing you to operate a mullet drive and still use hydraulic brakes.

#mullet #train #match #MTB #derailleurs #shifters

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