Mullet: part 1.

26 07 2019

Mullet? reverse mullet? party at the front, business at the rear? who knows what the terminology will settle on, but different wheel/tyre sizes on the same bike is seemingly a hot topic at the moment.

Now, bikes like these have been around a looooooooong time. Ibis and Cannondale stick out in my memory for producing bikes with smaller rear wheels before there were disc brakes or suspension. Then there was the Trek 69er line up.

My first experience of riding a mullet bike was at the singlespeed worlds in 2007. My friend Damo brought his Cog bikes over to race from Australia and he was a big proponent of 29 front, 26 rear. The bike rode really well. for some reason you could throw weight over the rear and unweight the front more easily than on a full 29er. Perhaps because of the smaller diameter and therefore shorter stay length. It was fast in the corners and felt nimble to ride in the tricky stuff. The 29er front maintained the roll over and I didn’t notice any loss in straight line speed. The rear didn’t feel like it was moving with any greater amplitude over bumps or steps.

The why’s and wherefores of the effect (or not) of wheel size, weight and gyroscopic stability are areas of great discussion. A few years ago there was a partly interesting thread on empty beer about the gyroscopic stability of wheels on fat bikes. My take on it was that although there shouldn’t be any clear discernible effect from changes in wheel mass or size in any real terms (because they are all in reality, broadly similar), in certain circumstances, there might be. For example, when in the air or turning and leaning.

Why? sit in a swivel chair and hold a decent size, rotating wheel in line with your body. Then hold it at an angle and the chair will rotate. Different sizes of wheel exert different forces in this circumstance. A 2″ diameter wheel may not rotate you. A 26″ definitely will. My view is that there might just be enough difference at different lean angles and radiuses of wheel to effect the handling of the bike. Maybe.

Recently, a new company called ‘Mullet Cycles’ arrived. Their technical blurb is a little hard to decipher but I suspect there is some truth in there. Now ‘scrub radius’ is a concept looking at suspension and wheel geometry. read about it here. How to apply this to bicycles is tricky, but there is no doubt that when leaned, the point at which you are weighting the bike and the lean angles, turning radius and traction are affected. Worth reading this probably.

Wheels on a bike do different things. So it seems sensible to prioritise in order to get the best out of the system. Loic Bruni, current leader in the DH World Cup and Martin Maes (EWS honcho) are both racing mullet bikes. Loic at least is known for his detailed and data acquisition approach to racing. There certainly doesn’t seem to be a significant loss when moving to a mullet set up. I think it is well worth experimenting, as long as the frame is not pushed into weird geometry by the switch.

Following my experience with Damo’s bike, and with the evolution of the 29+ tyre segment, I ended up using a 29+f/29r set up on my Jones for a while. It is a rigid bike, of course, so the increased ‘plush’ up front was a boon, but the low traction Knards limited things somewhat.

As a result, I experimented with a fat ‘snow’ tyre up front and a 650b x2.6 rear (the original b+ tyre, the wtb Trailblazer). Then when B fat became a thing, This provided the perfect set up (IMO) for the Jones. It slightly affects geometry – pushing the angles back a little, mitigated by rotating the EBB and thus increasing relative bb height and increasing seat angle, whilst retaining the slightly slacker front end.

 

Soon after this, my primary tyre set up was to look to a larger front tyre and or wheel for all my bikes. The fat bike went to a 26×4.5 then 4.7 with a 26×3.8 on the rear. Or sometimes a 27.5×3.8f and 3.0r. Or sometimes a 29×3.0f 27.5×3.0r. My vertigo cycles rigid mile muncher, Maul, went to a 29×3.0 front, 29×2.2 rear then backed off slightly to a 29×2.6 front, 29×2.2 rear.

Kraken, was designed around a 27.5×3.0 front, 27.5×2.8 rear which worked well with the 130mm travel fork. Originally, I had been keen to use a 27.5×3.8 Hodag which in true measurements is only slightly larger than the Highroller 2 when mounted on a 45mm i rim. I had also thought this bike might occasionally be used with a rigid fork and 29×3.0 Minion front wheel, but it is so good the way it is I have never wanted to dismantle it. So this brings me to Leviathan – the fraternal twin of Kraken….and my first bike designed specifically to be a mullet. More on this in part 2.


Actions

Information

One response

1 08 2019
Nick Rutter

This is something I’ve always done, coming from a background of BMX through the 90’s and early 00’s. The classic CompIII combo of 2.125f and 1.75r just worked so well, I could never understand why it never seemed to crossover to mtb’s.
I experimented with tyre sizes on my older 26’s with trials rims and Conti Diesel 2.5s, then when Surly brought out the Knard, that went straight on to my KM. Not, as you said, a great tyre, but opened up possibilities.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s




%d bloggers like this: