Pearl Izumi’s new X Project shoes are the fruit of a several-year-long project to develop a shoe that offers the best of both worlds: stiffness where it counts for power transfer, but grip and flexibility for walking.

According to Tony Torrance, Pearl Izumi’s product manager for cycling footwear another problem with stiff, high-performance mountain bike shoes is that the tread blocks are usually made from nylon rather than rubber. That means walking in them is made doubly tricky because the sole is slippery on wet surfaces.

Torrance is a mountain biker and dirt bike rider whose engineering background includes endurance testing cars for GM and coming up with Pearl Izumi’s 1:1 shoe insoles with interchangeable arch support and forefoot cant inserts. He’s clearly been living and breathing X Project shoes for a couple of years, and he’s been helped in the development by Pearl Izumi rider and living legend Brian Lopes.

The idea of the X Project shoes, was to create “a shoe that walks and hikes as well as it pedals,” said Torrance. He thinks Pearl Izumi has succeeded, and our first impressions are that he’s right.

So confident is Pearl Izumi that these new shoes are something special that Pearl Izumi Europe flew a group of mountain bike journalists from all over Europe to Sardinia over the weekend of October 13-14 so we could try them out.

Cutting up shoes

The first step in the development of the X Project was to hack up a bunch of shoes and find out which parts of the sole actually need to be stiff for efficient power transfer. Torrance worked with Ray Browning PhD, the director of the Colorado State University’s Physical Activity Energetics/Mechanics Lab to test new sole designs. This process involved hooking riders up to monitoring gear and having them ride at fairly high intensity while measuring their performance.

They found that a stiffer sole is not always better. There are parts of the sole where you don’t transfer power, particularly the heel and toe areas. Pearl Izumi could safely make those areas flexible and improve the walkability of the sole without sacrificing power transfer. Torrance therefore designed a tapered carbon fibre sole plate that is flexible at the front and back, but stiff around the cleat.

The game was afoot, but the next stage of development took a year: making the sole both light and grippy. “Combining plastic lugs with rubber tips for light weight and traction was the hardest bit to develop,” says Torrance.

The problem is that you can’t just glue a bit of rubber to a plastic sole. It won’t stay attached as the sole is pulled sideways as you walk. The solution was to co-mould the rubber tips into the sole. Rather than using Pearl Izumi’s Chinese factory, Torrance had to go to Italy to find a company that could manufacture the sole.

Making the sole light was a challenge too. Big tread blocks are heavy, so to keep the gram count under control, the X Project sole has hollow blocks.

One feature that’s missing from the X Project is any sort of replaceable tread. Torrance said this had been considered and rejected on the grounds of weight; the idea for version one of the X Project was to make a very light shoe. Claimed weight is 320g. In the hand and on the foot, they certainly feel very light for a mountain bike shoe.

Pearl izumi has form in making shoes that you can walk in as well as ride, so for te X Project, Torrance stole an idea from the X-Alp series and put a layer of EVA foam under the heel to absorb walking shock.

On the trail

After Tony Torrance’s shoe-and-tell we headed for Sardinia’s rocky trails to find out how the shoes worked in the field.

The executive summary is: they’re good. Our test samples were the very first ones from the factory to exactly follow the design of production shoes. That had one downside: this writer is a 43.5 in Pearl Izumi shoes, but only 43 and 44 were available. There will be half sizes in full production shoes, and when we can get 43.5s we’ll be able to say more about the details of the fit.

But despite being slightly loose, the X Project 1.0 shoes we tested felt good, with firm support underfoot and a comfortable, moderately stiff upper that held our feet in place without being overly hard.

The top strap is quite low on the upper foot, so it doesn’t load all the sensitive ligaments over the tarsus. We tweaked the side-to-side position of the strap so that the padding sat in the middle of our feet and didn’t notice it at all after that.

In fact, on the bike, the X Project shoes feel almost exactly as you’d expect a pait of high-end mountain bike shoes to feel. They’re comfortable, the sole is stiff and the upper holds you in place whether you’re just cruising along or going hell-for-leather.

When our ride turned into an impromptu race to the beach (for the hell of it) followed by a race back to the hotel to escape the gathering afternoon rainclouds, we weren’t thinking about the shoes so much as wondering whether we could keep up with Brian Lopes, who was putting the hurt on us all despite hardly breaking a sweat.

If you pay close attention, you can tell that the support is all in the mid-foot, from ball to the back of the arch, but it’s hard to be sure that’s not expectation bias.

What we are sure of, though, is that the X Project shoes are definitely easier to walk in that your typical super-stiff shoes. You can feel the toe and heel flex as you walk and as a result you stay in contact with the ground rather than slipping around. If your rides typically involve any significant amount of walking, then the X Project is definitely worth considering.

The range

There will be three models of X Project shoe.

At the top is the model we have here, the X Project 1.0. This has the full X Project sole with an upper made from thermoplastic urethane and mesh for light weight and ventilation. A micro-adjust buckle makes it easy to slightly loosen or tighten the upper as you ride and there are three mounting points for the top strap so you can centre the padding on your foot. The X Project 1.0 will be available in January and will cost £229.99. The X Project 1.0 will be available in sizes 38-47, including half sizes, plus 48 and 49.

The X Project 2.0 will be a shade heavier and will be available in a women’s version with a narrower heel. The upper is made from synthetic leather rather than urethane and mesh, which Tony Torrance pointed out would probably make it more suitable for UK conditions than the X Project 1.0. The X Project 2.0 will use the same sole as the 1.0 but will have a standard ratchet buckle rather than the 1.0’s micro-adjust ratchet. The X Project 2.0 will cost £169.99 for both men’s and women’s versions and will be available in men’s sizes 39-47, including half sizes, plus 48 and 49 and women’s 36-43 including half sizes.

Finally, X Project 3.0 uses some fibreglass in place of carbon in the sole to save some cost. The upper combines mesh with synthetic leather and has slighty simpler consruction over all. The X Project 3.0 will cost £129.99 for both men’s and women’s versions and will be available in men’s sizes 39-47, including half sizes, plus 48 and 49 and women’s 36-43 including half sizes.

All three X Project men’s models are made on the same last as Pearl Izumi’s road shoes, as clear an indicator as there is of their performance intention. The women’s shoes are shaped on a new last that Torrance describes as “the evolution of our current women’s last”.

The X Project 1.0 and 2.0 come with the 1:1 insole system with interchangeable heel and forefoot inserts. 1:1 insoles are available separately or £34.99/pr.

More information: Pearl Izumi