Michelin is one of the biggest tyre companies in the world. It makes tyres for cars, motorbikes, plane, earthmovers and of course bicycles. The bike bit might only be a fairly small part of the Michelin rubber empire, but it can call on the R&D of all the rest of it. Which means that people buying massive dumper trucks are helping to pay for new bike tyre designs.
The new Dual Compound tyre range doesn’t have much to do with dumper trucks, but it does have quite a lot to do with motocross and motorbike enduro racing. Tyres using similar technology have one eleven World Championships in the last couple of years. On the bicycle side, Julien Absalon road Dual Compound tyres to Olympic and World Championship victory in 2004.
So what’s it all about ? The idea is to avoid a compromise that usually faces tyre designers. You can choose soft rubber that’ll grip better but wears faster and means that you have to design your knobbles differently to avoid them folding over under load. Or you can choose hard rubber that lasts well, gives a stable tread but tends to slide over things. It’s a choice between “grip” – adhesion between tyre and surface – and “bite” – mechanical traction, or the tyre digging in to the surface.
Michelin’s new tyres use both. Now that’s not a totally new idea, there are plenty of tyres out there with different rubber compounds in the tread. But usually you have something like a hard, fast-rolling compound down the middle and softer, grippy stuff on the edges. Michelin have done something different – the hard rubber is inside and the soft rubber on the outside. Cut through a Dual Compound tyre and you’ll see that each knob has a core of hard rubber and a coating of soft, so you get the stability of hard rubber with the grip of soft stuff. As an added benefit, the hard inner rubber gives better puncture resistance than having soft all the way through. As you’d imagine, making these tyres requires some pretty cunning techniques, and Michelin has developed an exclusive “coextrusion” process – both rubber compounds are forced through the same mould at the same time, so there’s no air or anything between them.
Dual Compound is found on all of the new Expert range of tyres. That’s one-third of Michelin’s new range segmentation, with the Tribe range is for DH/freeride/4X/that kind of thing (this is where classics like the DH16 and DH Mud live) and there’s a recreational Country range. Probably the two most interesting tyres in the Expert range are the XCR All Terrain and its bigger brother the All Mountain. The tread design is essentially the same for both tyres, but the XCR AT is a 2in tyre and the All Mountain is a 2.2in. The tread pattern combines different knob shapes and sizes in pursuit of that perfect mix of straight-line traction, cornering grip and mud clearance.
The other Expert tyres, like the 2.2 or 2.5in Mountain X’trem, XCR X’trem, XCR Mud and XCR Dry, take existing Michelin tread designs but render them in Dual Compound rubber, while the XCR Road 26in slick doesn’t have any tread at all.
Full details of Michelin’s MTB tyre range are available at two-wheels.michelin.com. We’ve got some XCR AT and All Mountain tyres on bikes at the moment, we’ll let you know how we get on…