Mullet bike: What's behind the mixed-wheel trend in mountain biking?
29-inch front wheel, 27.5-inch rear wheel – the so-called mullet setup has become virtually indispensable in the mountain biking scene. What looks like a compromise is often a better choice in practice than a pure 29er or 27.5er bike. We explain here exactly what the concept is, who benefits from it, and whether the mullet principle also makes sense for e-MTBs .
By Vincent Augustin 4 minutes read time
Published: May 28, 2026 | Updated: May 28, 2026
You can also find a compact overview of the most important terms related to the topic in our glossary article on mullet bikes .
What is a mullet bike?
The term "mullet" originates from the world of 1980s hairstyles – "business in the front, party in the back". Applied to mountain biking, this means: a 29-inch front wheel for smooth running and efficiency, combined with a 27.5-inch rear wheel for agility and playfulness.
This setup isn't a makeshift solution, but a deliberate design choice. Many manufacturers now offer frames specifically designed for the mixed-wheel format. However, many existing bikes can also be converted into a mullet with the right modifications – provided the frame geometry allows it.
The logic behind it: Why two different wheel sizes at all?
For years, the MTB scene was divided: 26 inches, then 27.5 inches, then 29 inches – each wheel size had its followers and its clear advantages and disadvantages. The mullet setup attempts to combine the best of both worlds.
The key principle: the front and rear wheels have different roles while riding. The front wheel rolls over obstacles, guides the bike into corners, and provides stability. The rear wheel carries the rider's weight, provides traction, and influences agility during changes of direction. Having both wheels the same size is a compromise – the mullet setup, on the other hand, optimizes each axle separately.
The 29-inch front wheel: Stability and rolling characteristics
A 29-inch front wheel has a larger contact angle than a 27.5-inch wheel. This means:
- Improved ability to roll over obstacles (roots, stones, edges)
- Smoother running at high speeds
- Increased straight-line stability – particularly advantageous on technical descents
- Larger tire contact patch at the same tire pressure → more traction at the front
Especially on fast, rocky trails, the large 29er front wheel makes all the difference: It runs more smoothly, is harder to knock off course, and gives the rider more control and confidence.
The 27.5-inch rear wheel: agility and maneuverability
The smaller rear wheel brings a different quality to the game:
- Lower center of gravity – the frame sits lower, making the handling characteristics more active.
- More clearance for tires in the rear triangle – larger tires possible
- Faster steering in tight corners and switchbacks
- More "pop" when actively riding – jumps and manuals are easier to initiate with a 27.5" rear wheel.
- Improved pedal clearance at the rear triangle with short chainstays
In addition, there is a geometric effect: the smaller rear wheel lowers the bottom bracket center of gravity slightly, which further improves the driving dynamics – similar to a lowered car in a curve.
Who would benefit from a mullet setup?
The mullet is not a panacea – but for certain types of riders and terrains, it is a very compelling choice:
Trail and enduro riders benefit the most. Those who combine technical sections with fast stretches need a bike that can do both: roll smoothly and react actively. That's exactly what the Mullet delivers.
Shorter riders often find themselves limited by a pure 29er: the wheels appear too large in relation to the frame, and the geometry isn't optimal. A 27.5-inch rear wheel noticeably improves the proportions and handling in these cases.
Technically oriented riders who actively move the bike – jumps, wheelies, tight switchbacks – will appreciate the more lively rear end of the Mullet.
Riders who focus solely on uphill performance or primarily ride on quiet forest roads will notice less of a difference. For them, a pure 29er setup is often sufficient.
Mullet and e-MTB: A powerful combination
In the e-MTB sector, the mullet setup is becoming increasingly interesting – and for a specific reason: e-MTBs are heavier than muscle-powered bikes. This increased weight alters the handling, especially at the rear.
A 27.5-inch rear wheel can help keep a heavy e-MTB full-suspension bike agile and manageable despite the added weight. The shorter chainstays allow for more tire clearance, which permits larger, grippier tires that improve traction on a heavier bike.
At the same time, the 29-inch front wheel brings the usual smooth running – especially on descents at higher speeds, which many e-MTB riders experience more frequently due to the motor-assisted uphill riding.
The result: an e-MTB that rolls efficiently uphill and remains agile and controllable downhill despite its weight.
Build your own mullet or buy a ready-made one?
Many bikes can be converted to a mullet setup – but not every one. The following are important:
- Frame compatibility: The rear triangle must be able to accommodate a 27.5-inch wheel. This is possible with some 29er frames, but not with others.
- Thru-axle format: The front and rear wheels must be compatible with the installed hubs.
- Geometry adjustment: A mullet conversion changes the effective bottom bracket height and therefore the riding feel. This is usually desirable – but it's worth checking the effect on the geometry beforehand.
For those who want to be on the safe side, it's best to choose a frame that's designed for the mullet format right from the factory. These bikes already have their geometry optimized for the mixed wheel size and offer the best handling.
Comparison: 29/29, 27.5/27.5 and Mullet at a glance
| Characteristic | 29/29 | Mullet (29/27.5) | 27.5/27.5 |
|---|---|---|---|
| Rolling behavior | Very good | Very good (front) | Good |
| Agility | Lower | High | High |
| Handling | Calm, less active | Balanced | Very active |
| focus | Higher | Medium | Lower |
| Suitable for | XC, Marathon, fast trails | Trail, Enduro, E-MTB | Freeride, Dirt, rider < 170 cm |
| E-MTB suitability | Good | Very good | Good |
