While the majority of bikes on the market are 29ers, brands are increasingly offering mullet configurations as an alternative. And while the early mixed wheel models were little more than frankenbike mash-ups, the bikes you can buy now are usually bespoke variants without compromises in geometry. 

But why would you choose one? What are the pros and cons? And can you feel the differences on the trail? Armed with two of INTENSE’s latest enduro bikes, the Tracer 279 and Tracer 29, we set out to find some answers. 

Intense Tracer 279 mullet bike (left) Vs Intense Tracer 29 (right)

The theory

Some of the oft-repeated generalisations about mullet bikes are that they are more agile, playful, and indeed fun, than full 29ers. Hand in hand with that is the assertion that mullet bikes change direction more easily, and that they take less effort to manual or lift the front end.

Additionally, the smaller rear wheel gives more bum clearance, and it helps with acceleration and braking, at the expense of improved bump rollover and high speed stability. 

There’s no getting away from the fact that 29ers give you less bum clearance, so if you predominantly ride steep tracks, and don’t have long legs, you’re probably better off on a mullet set-up

The bikes

The Tracer gets 170mm of travel front and rear and comes in two wheel size options, with near identical geometry and specs, making them a really good choice for trying to isolate and identify any differences on the trail. 

There’s a 45mm difference in wheel diameter between the two INTENSE Tracers, which has an impact on many aspects of the ride and handling.

Indeed, when we measured the two bikes in size large, the only real difference was in the chainstay length, with the Tracer 279 mullet bike running a short 437mm rear centre, and the Tracer 29 coming in at a more common 450mm. 

INTENSE fits the Tracer with a flip chip, and the bikes come stock with the 29er in the low position and the mullet bike in the high position. This gives near identical geometry and BB heights. 

The MX-wheel Intense needed less effort to initiate turns, but this was only something we noticed on the first run when swapping from the full 29er – you quickly compensate for the reduced input required

The biggest spec difference between the two bikes is the shock. On the mullet it’s a coil shock and the 29er gets an air shock. As such, we ran both bikes with 28% sag. Other minor variations include the tyre treads (Maxxis Minion DHF/DHR II on the mullet, Assegai on the 29), but the casings and compounds are both the same. 

On the scales, the 29er was the lightest, although only by 150g. What’s interesting is that the rear wheel is lighter on the mullet bike – it’s smaller, after all – while the shock is heavier, so the mullet bike actually has a marginally better sprung-to-unsprung mass ratio. 

The Tracer 29 was quicker on the climbs, but the gearing is taller because of the larger diameter wheels

With the same size chainring and cassette on both bikes, the actual gearing on the 29er is slightly taller because of the larger rear wheel. Fitting a 32t chainring on the mullet bike would even things out. Equally, the brake rotors are 203mm on both bikes, but the larger rear wheel on the 29er would benefit from a bigger rotor, especially on long descents.

Timed runs

We undertook timed runs on both bikes, utilising a short downhill and a gradual fireroad climb. After some familiarisation runs, an A-B-A pattern was used, with two runs on the mullet bike, followed by four runs on the 29er, and finishing up with two runs on the mullet. 

The downhill was deliberately chosen to favour the mullet bike, with a sequence of alternate turns down a fairly steep hill. A straight, fairly smooth, moderate gradient fireroad was used for the climb. Effort was kept low (under 140bpm) using a heart rate monitor and restricted breathing. 

On the downhill there was not enough variation to draw any conclusions from. The mullet bike achieved the fastest times, but the average times were only 1.1% different. The climb, on the other hand, showed an advantage to the 29er of 4%, combined with a slightly lower average heart rate. 

Shorter chainstays make it easier to get your weight back on the mullet bike, so it takes less effort to manual

Rider feedback

The first thing we noticed when shifting between the two bikes was that the 29er felt roomier. Like it was a slightly bigger bike. This is because we shifted our weight back between the axles when standing up to compensate for the longer chainstays. Conversely, the mullet bike felt smaller, because the shorter chainstays encouraged us to shift our weight forward to keep the same weight distribution. 

We reduced the pressure in the fork on the mullet bike by around 10%. This is because our weight was further back over the rear axle relative to the 29er while descending, leaving lots of unused travel and the front end feeling too high.

On the descent, both bikes felt equally manoeuvrable and willing to turn, although we buzzed our backsides on the 29er every run. Until we swapped bikes a third of the way through the test, when both riders were really tuned into the handling. At that point, the rider switching from the 29er to the mullet bike used too much force to turn, while the rider who had just jumped on the 29er ploughed straight on at the first corner. 

A longer wheelbase and keeps the 29er nice and stable and makes the bike feel bigger, because you move your weight backwards to achieve a centred mass between the axles

Clearly we had calibrated our inputs to one bike, and switching to the other had thrown them out. The mullet bike needed less effort to change direction, while the 29er needed more. 

But, while that run showed a marked difference, on the next descent we had both recalibrated our brains and the handling felt completely natural. Neither rider felt there was a noticeable difference in climbing ability between the two bikes, despite the difference in times.

MX bikes are a lot of fun to ride but the differences are not as significant compared to a 29er as the marketing would have you believe

Conclusions

While not a definitive test, our little experiment did raise some interesting points. The main one being that there’s not the yawning gap in performance and handling between the two bikes that you might believe from the marketing. Equally, humans are amazingly good at adapting to small changes. One run was all it took to make the subtle change in steering force when switching between the 29er and the mullet bike. 

Was the mullet bike more agile and easier to turn? Yes, but not so much that you’d lose any sleep over. Was it more fun? That depends how you define fun. The one thing you can’t argue with is that there’s more bum clearance on the mullet bike, and if you’re riding steep tracks, and you’re of average height or less, then that could be a deal maker. 

Conversely, if you’re racing enduros then the 29er will save you energy on the climbs, and that’s a gain worth having. 

For the most part though, deciding between a mullet bike and a 29er will come down to your height. If you’re between 5ft 9in and 6ft, then you can choose either bike depending on your priorities. Anyone under 5ft 9in will be better off on a mullet bike, not only for the extra clearance, but because the front and rear centres are better proportioned, it’s more agile, and the bike feels smaller than the 29er even though the reach is the same. Which means those of you over 6ft are better served by the 29er, for the opposite reasons.