Five Questions with Michelin's Vincent Ledieu Now that tubeless (or at least, "tubeless ready") is the base-line for all mountain bike tires, what do you see as the greatest challenges to making a competitive all-mountain/trail bike tire? Michelin's history as a high performance tire maker is one of the headwaters of professional motor racing and in cycling, the French tire maker has molded a stellar reputation among road riders. Michelin's impact upon the mountain bike market, however, has been less successful, but we have seen an about-face recently as Michelin has aggressively turned its focus upon enduro racing, teaming up with the likes of Fabien Barel and Jérôme Clementz in a successful bid to win EWS races. And, according to Michelin, they are just getting started.
Successful tire design is as much about know-how as it is about luck and good timing. Changes are in the wind as enduro riders press tire makers to blend downhill durability and grip with lighter, fast-rolling casings. Adding to the pressure to innovate is the switch to wider rims and the subsequent need to rethink tread profiles to adapt to a wider contact patch. As a result, tire makers face a changing marketplace where a combination of new technology and a "sharpening
" of established practice will be required to stay on top of their game. For Michelin, this is a crisis of opportunity. We spoke to Michelin tire designer Vincent Ledieu about his take on creating the ultimate mountain bike trail bike tire.
AM/Trail use is really interesting to study. I have always said making tires for this use is really hard. You need rolling efficiency and grip. You need light weight and robustness. Those are the two main balances that a tire designer is always thinking about. I dream about it! Tubeless ready (TLR) gave us the opportunity to prevent tires from puncture. The sealant is working quite well and enables the rider not to get stopped because of a punctured tire. But, TLR is not preventing riders from pinch flats. [In the case of tubeless], pinch flats damage tires, and can put a stop to a riding day if the tire is damaged too much. Another main point is to define new tread design and compound combinations so that the balance between grip and rolling efficiency is improved. This is a challenge for Michelin's Bike Team. Tell us Michelin's thoughts on where rim widths should end up for all-mountain/trail/enduro and how that affects your tire designs.
Modern all-mountain and trail bikes are light and efficient enough to climb XC trails, and they make it possible to descend trails that were once the exclusive domain of DH bikes. How does Michelin balance the two problems - of making a tire tough enough to survive DH trails, yet lightweight enough to pedal and climb efficiently?
Our challenge is to maintain Michelin DNA in our tires as the rim standards change. Rim width impacts a tire's handling. It really depends on tread design profile. I mean, a rounder tire will become squared, so when changing from a narrow to a wide rim, handling of the bike we’ll be completely different.
A rounder tire gives a more predictable grip on the angle. Changing the shape of the tire will change the grip on the angle. Today, we changed [widened] our rim standard to adapt our future tread designs to keep that predictable angle grip.
New uses are coming so fast in bike industry that we have to think differently to design our next tires. Using a new raw material is an issue we are considering, and also changing the profile and structure of the casing could be a solution. Michelin likes that kind of challenge, and R&D is in our DNA. I’m working on some ‘concept’ tires that could change the actual balance between mass and robustness. How important is the rubber composition as compared to the actual tread design? How do the two components work together?
Rubber gives grip by its contact on the ground while edges and sipes give grip by digging into the ground. For each use, XC to DH, you have to think of compound and tread design as a couple. Stiffness is the key to get a tread pattern sticking to the ground. If during a test session I get a really sticky soft compound, but the rider feels an immediate and non-progressive grip on the angle - maybe the design of the knobs need to be adapted to get more stiffness. For example, Michelin's Wild Grip’R shows a good adjustment of rubber stiffness depending on its tread knob design. The center compound stiffness [we use] is higher than the shoulder compound because the central block's definition gives less stiffness than shoulder’s blocks.
Another example is the Michelin Wild Race’R Ultimate, our XC Race tire. The tread design is really low, so it gives a very good rolling efficiency. But, if we kept the compound hard like people used to ride in XC race, the grip efficiency would be not so good. Rudy Megevand, the previous tire designer, decided to put a Gum-X compound, coming from enduro, to achieve good grip without challenging rolling efficiency. It was a successful idea. If you had one message to voice about the future of tire design as it pertains to all-mountain and enduro, what would that be?
Michelin all-mountain tires come from enduro experience garnered from EWS racing. The perfect tire must have more grip, more robustness, more rolling efficiency, and less weight. We know the need, we like challenges, we think we can do it.
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