OK: So What's a Gravel Bike Mullet Build?

by Marc Basiliere March 10, 2020

Business in the front, party in the back.

Alright, the name is more than a little cringeworthy. But given the saying about the haircut for which it's named, it isn't hard to understand why mullet might be an appropriate description for road/mountain hybrid drivetrains. Taking advantage of the cross-compatibility within SRAM's AXS wireless drivetrains, Mullet builds use road drop bar brake/shift levers to control mountain rear derailleurs, cassettes, and chains. The best of both worlds? Well, they might just be.

It's not mystery that at Lindarets we spend a lot of time thinking and talking about bicycle -and specifically gravel bike- drivetrains and gearing. There are countless combinations of drivetrain components, gear ratios, perspectives, and rider preferences, which can make building the 'right' bike awfully daunting.

Why Does the World Need The Mullet Build or Mullet Bikes?

Much of the resistance to single-ring chainrings comes from a couple of places. First, the lack of range- the breadth of gear choices between the highest and lowest options. The widest-range Shimano Ultegra road group has a 428% range- in other words, the highest gear is 4.28 times the lowest. The gravel-oriented GRX 8xx groups offer 460%. The first proper gravel 1x group (SRAM's Force1) has a near-Ultegra 420% range thanks to its wide-range cassette.

There are visual, weight, noise, and chain security advantages to single-ring drivetrains. The big tradeoff comes in the form of step size. Tooth count doesn't really tell the story: shifting from an 11t to a 13t cog makes a much bigger difference in terms of cadence than a 15-17 or 25-27 shift. Road cassette steps tend to top out around 15% and average roughly 10% between adjacent cogs. Wide-range gravel and mountain cassettes top out at about 17% and average 13-14% between cogs.

Does it make a difference? It depends on the rider. Most of us were taught to keep our cadence around 90rpm. Upshifting from 90 would put a rider at 81rpm on a GRX/Ultegra cassette, on a wide range cassette that same upshift would put the same rider at 79rpm. It may feel like a big difference in the moment, but on steeper mixed terrain it's less noticeable than when road riding in a pack.

So why are Mullet Bikes exciting?

Adding a twelfth cog makes a double-beating 500% range possible, without resorting to uncomfortably large steps. The 14% average step shown above for the Force/Red AXS 44 x 10-50 (our Mullet Build) is a little misleading- gears 2-12 are the exact same as 1-11 on a 13% step average Force1 10-42. The larger step from the 42t to 50t cog throws off the average, but this extra massive cog allows for even lower gearing for the steepest climbs. It also allows most riders to bump up to a 44t or even 46t chainring up front so your bike gets a few extra MPH in the high end without a sacrifice to the bikes ability to climb. The result, you'll spin out less at high speed and you can still climb like a goat, all while enjoying the chain security and simplicity features of a 1x drivetrain.

The benefits don't end there. Compared to the more road-focused Force AXS 2x12 drivetrains, a Mullet build offers more range, a wider mountain-proven Eagle 12-speed chain, and a more secure mountain bike clutched derailleur. And, in what may come as a surprise, the steps between cogs are more consistent, with nice smooth curve from highest gear to lowest.

Despite the truly massive cassette, removing redundant parts saves roughly 1/2lb over a similar 2x build. Right or wrong, we can't help ourselves when it comes to shaving weight- and we've seen far, far, far worse ways to shave 1/2lb from a bicycle.

Ergonomically, SRAM Red and Force AXS drivetrains are hard to fault- they can be programmed to work any number of ways, but typically leave our shop with the right paddle shifting down the cassette, the left shifting back up. The hydraulic disc brakes are powerful and easy to modulate and the lack of shift wires further emphasize the Atalaya's already clean lines.

The big downside, of course, is cost. The Mullet Build requires SRAM's highest end components. While they work beautifully, it can be a tough pill to swallow for some.

Are Mullet Builds the right choice for everyone?

Maybe not. And if the majority of your rides are on paved roads probably not- doubles and tighter ratios still rule on group rides and gradual climbs. We offer all drivetrains, 1x11 mechanical, 1x12 mullets, and 2x on our gravel, monstercross, and bikepacking bike builds for a reason. For those who spend the bulk of their time on rough roads or climbing and descending steeper terrain the advantages are real- and the performance drawbacks are probably smaller than a lot of riders might think. If cost is an issue, we've had plenty of riders love more affordable 1x11 builds using Shimano GRX or SRAM mechanical groupsets. Have a read of our gravel bike gearing article for more on that drivetrain.

If we're honest though, the Mullet Build might be the option we're currently most excited about.

Is it time to start building your dream gravel, monstercross, or bikepacking bike?

Explore our current selection of fine Titanium adventure bicycles. Our standard builds offer plenty of drivetrain choices including the Mullet. But we're also happy to work with you on a fully custom build on our gravel/race oriented J.Guillem Atalaya or the more endurance/comfort oriented Chiru Kegeti.