The "Mullet" in Gravel – How to Combine MTB and Road Bike Components? A Guide for Custom Bike Builders
Mullet , the classic "business in the front, party in the back," in the cycling world refers to a drivetrain configuration that combines a road-style shifter with a mountain bike derailleur and cassette. The result? A gravel bike that looks like a proper road bike but climbs and shifts like a full-fledged mountain bike.
Until recently, this setup was the domain of enthusiasts and DIY mechanics. Today, with the growing popularity of gravel bikes and the ever-widening selection of manufacturers, the mullet is becoming a natural option for those who want more gears, greater technical freedom, and… more fun from a custom setup.
Or maybe a cross bike? Check it out - Cross bike, what kind and for whom?
Why make a mullet at all?
On paper, road and MTB drivetrains differ in seemingly minor details: different chain lines, cassette ranges, derailleur cage lengths, and cable travel. But in practice, this often means a dilemma: either a beautiful shifter and a small range, or a large range and MTB-style control logic.
Mullet is an attempt to reconcile these worlds:
- Larger cassette (e.g. 10-50T) at the rear = better climbing, better bikepacking load.
- Road levers = aesthetics, aerodynamics, dropbar ergonomics.
- Greater compatibility with gravel frames without having to sacrifice wide gear ratios.
- Possibility of using a 1x crankset without a front derailleur – simpler, lighter, less prone to failure.
Most popular mullet configurations – what about what?
🔴 SRAM Mullet AXS
The most "official" mullet setup currently available on the market. SRAM fully supports the combination of:
- SRAM Rival/Force/Red eTap AXS levers (drop bar)
- SRAM Eagle AXS derailleur (MTB)
- 10-50T or 10-52T cassette
- Eagle chain (e.g. NX or GX)
No need for complexities—everything works within a single AXS system, wirelessly. Plus, there's a great configuration app and the ability to expand with droppers and sensors.
Who's it for? For those who want a maintenance-free, clean setup with huge scope and aren't afraid of a higher price.
🔵 Shimano Di2 Mullet (semi-official)
Shimano doesn't advertise mullet configurations, but they can be assembled. For example:
- GRX Di2 12s levers
- XT Di2 or XTR Di2 derailleur (12s)
- 10-51T Micro Spline Cassette
- Chain CN-M8100 (Deore XT)
It works - although you need to remember to have compatible firmware and full E-Tube.
Who's it for? For Shimano fans who don't want to give up Di2 but still need a wide range.
⚙️ Mechanical Mullet (SRAM + MTB)
Many people still use mechanical mullets, although they don't always work flawlessly. Most often:
- SRAM Rival/Force 1 levers (mechanical, 11s)
- SRAM GX or NX derailleur (11s MTB)
- 11-42T or 11-50T cassette
- Narrow-wide crown (e.g. 42T)
It works, but you need to pay attention to the cage length and cable travel compatibility. Not all shifters will work perfectly with MTB derailleurs.
For the curious - How is a bicycle built?
What to watch out for when assembling a mullet?
- Cable travel: SRAM and Shimano have different cable travels – not every shifter will work with every derailleur.
- Chainline and Cage Length: Make sure the frame has room for the Cage and large cassette.
- Cassette and freehub: SRAM 10-50T cassettes require an XD freehub, Shimano Micro Spline – other than HG.
- Chain length and hanger angle: Check that the derailleur works well with the cassette and frame.
Is it worth it?
The Mullet is a great option for those who want to get more out of their gravel bike—both functionally and by customizing it to suit their riding style. It's a solution that will be particularly appreciated by those who ride with panniers, explore more challenging trails, or simply want to feel like their bike is more than just a catalog compromise.
However, this isn't an option for everyone. Mullet requires more expertise when selecting components—it's easy to stumble upon incompatible components. And while AXS and Di2 make many things easier, they also increase the price of the entire setup.
We're building a gravel bike together - custom at Antymateria
At Antymateria, we don't just sell bikes—we build them from the ground up, based on what truly makes sense for the individual. If you're thinking about a gravel bike with a mullet setup but aren't sure how to approach it, we can walk you through the entire process. From co-ordinating component selection, through frame selection, to building the finished bike and test riding.
Custom isn't just about a different stem or two colors to choose from. It's a real opportunity to create a bike tailored precisely to your needs, routes, and expectations. Whether you're starting from scratch or want to modify your current bike, we'll help you design and build it. So that it works. And so that you actually want to ride it.
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