Why We Keep Building Mullet Gravel Bikes

A mullet gravel bike runs road levers up front and a mountain bike drivetrain out back. Business in the front, party in the back. We've built plenty of them at the lab, and the reason riders ask for one comes down to one thing: an easier low gear.

The bike up top is one of ours: an ENVE MOG with an XX Eagle AXS Transmission derailleur, a T-Type 10-52 cassette and a SRAM Force crank.

What a mullet actually is

Your SRAM AXS road shift/brake levers stay on the bars. The rear derailleur, cassette and chain come from SRAM's Eagle AXS Transmission mountain group. It isn't a hack. SRAM says every AXS controller works with Transmission, road levers included.

The parts list:

1. Road AXS leversSRAM RED, Force or Rival shift/brake levers. The ones you already know.
2. An XPLR 1x crankThe wide road crank SRAM specifies for this build, for the right chainline. Something like the Rival 1x XPLR AXS Power Meter Wide crankset.
3. A Transmission derailleurXX SL, XX, X0 or GX Eagle T-Type AXS. It has to be AXS. SRAM's mechanical Eagle 90 and 70 won't work with drop-bar shifters.
4. A T-Type cassette and chainA 10-52 cassette like the GX XS-1275 or X0 XS-1295, plus a T-Type chain like the GX Eagle T-Type Flattop.
5. A frame with a UDHTransmission bolts straight to it with no hanger. No UDH, no mullet.

The gear you're buying

XPLR tops out at a 46-tooth cog. Transmission goes to 52.

Run the same 42-tooth ring on both. 42 divided by 46 is 0.91. 42 divided by 52 is 0.81. Your easiest gear gets about 11.5 percent easier.

That's the gear that keeps you turning the pedals on the steep stuff, late in a long day, or on a bike carrying bags.

Total range moves too. The XPLR 10-46 cassette covers 460 percent. SRAM rates Transmission's 10-52 at 520 percent.

What riders tell us

The low gear is the headline, but it's rarely the only reason. Here's what we hear from riders who've made the switch.

1. It's the bikepacking setupPut bags on a gravel bike and XPLR's easiest gear stops feeling easy. Riders who load up for overnighters or long ultra days say the 52 is the gear they live in on steep climbs.
2. The shifting doesn't flinchTransmission shifts cleanly under full pedaling load. Riders say it keeps doing that through mud, grit and standing water.
3. No hanger to worry aboutThe derailleur bolts straight to the UDH, so there's no hanger to bend in the car, in a bike box or on the trail. Packing for a trip gets a lot simpler.
4. A quiet chain on rough roadsThe clutch keeps the chain calm on fast washboard descents.

Three details that matter on the build

1. The chain. Transmission takes a T-Type chain only. XPLR runs a road Flattop chain. SRAM is clear that you don't swap them.
2. The wheel. T-Type cassettes fit an XD driver. On an XDR driver, SRAM says an XD cassette fits with a 1.85 mm spacer. We sort that out on the build.
3. The crank. Transmission needs the wide road crank to hit its 55 mm chainline, and SRAM doesn't list the standard 1x road cranks for it. It's an easy one to miss.

Build one

Want one like this? The MOG is in our ENVE builder. Pick a SRAM XPLR crank and the Transmission derailleurs show up next to XPLR, with every price listed. Our Factor builder offers the same mullet setup on ALUTO, OSTRO GRAVEL, ELARA and SARANA. Already have a bike with a UDH? Bring it by the lab and we'll talk through the swap.

Same levers. Easier climbs.