Pearl Izumi X Project - Interbike 2012

Fresh approach to high-end MTB shoes, with two-way flexible sole

With the X Project, Pearl Izumi climbed off the “stiffer is always better” train, and forged another path with a high-end mountain bike shoe that flexes. A lot.

A few companies offer walk-able mountain bike shoes, but they are typically aimed at either the recreational crowd or all-mountain riders. For performance-minded riders, the standard shoe has basically been a stiff road shoe with tread.

Take Pearl Izumi’s 2012 line, for example. There is the chunky X-Alp shoe, which the company says is quite popular at REI in the US and with cycle tourist in Europe; and there is the hyperlightweight Octane SL, which combines a road shoe with MTB lugs. In between – at the high-end – there was nothing.

For 2013, the X Project fills that gap. It’s a hyperlight shoe (320g) that’s stiff for pedaling but flexible fore-aft and side-to-side.

“The paradigm of mountain bike shoes comes from road — where it’s always about maximal stiffness,” said Pearl Izumi marketing director Geoff Shaffer. “Our X-Alp was inspired more from hiking footwear. We saw a void for the more performance-minded person, but someone who still faces the reality of hoofing it sometimes on their big rides. Also, for cyclocross, this is the perfect shoe.”

Raceable? Check. Walkable? Check

The X Project features a tuned carbon plate that tapers in shape and stiffness through the sole. It is thin and narrow at the heel, then tapers up to a wider, thicker section at the cleat, before again tapering to a flexible shape at the toe. Built into a TPU sole, the end result is a shoe that is stiff to pedal, but flexes generously at the toe and – perhaps just as importantly – torsionally as well.

“The challenge from (company president) Juergen Eckmann was to make an X-Alp shoe that appeals to cross-country riders,” said Philip Majure, Pearl Izumi’s director of footwear.

To test shoe efficiency, Pearl Izumi had a university physiology lab test riders doing one-hour efforts at 90 percent of threshold power on the X Project and a super-stiff shoe. The lab monitored the riders’ oxygen consumption as well as relative movement of the foot. They found no difference, Majure said.

Majure has decades of experience in the shoe industry, including time at Adidas and Sorel. He worked with Pearl Izumi’s Tony Torrance, manager for the X Project, on the formula for the shoe.

The tapered carbon shank is thickest near the cleat

X Project sole construction

The carbon plate measures 4mm at its thickest point, but is not solid carbon.

“We have layers of TPU squeezed between the carbon,” Majure said. “That way we can tune the flex and reduce weight, much like an Atomic Ski torsional bar. We did a version with full carbon, but it was too stiff at the toe.”

The sole is created in three main steps. First, the carbon shank is injection-molded with TPU. Then that carbon plate is brought to the mold where rubber tips are inserted at the base. Then TPU (brightly colored, in this case) is injected into the mold.

Alien blood is used in the production of the X Project soles. Actually, the green material is TPU, which is injection into the mold with the carbon shank and rubber traction tips

The plates and sole are made by Novation Spa in Italy.

“We do these soles in Italy for the same reason Nike Soccer makes its plates there — we can do things in Europe that you can’t yet do in Asia,” Majure said.

The sole is then bonded to the uppers, which are made in Asia.

An EVA foam heel bumper is included to absorb shock at what is often the initial point of contact when you hop off the bike.

“Cycling footwear is very conservative,” Majure said. “We’ve seen essentially the same thing — with the same white/black/red colors — from some of the same big companies for 20 years. We decided, let’s really push it with design and construction.”

Pearl Izumi has five X Project models total: the $250 1.0 (320g), the $210 men’s 2.0 (325g) and $210 women’s 2.0 (280g), and the $160 men’s 3.0 (330g) and $160 women’s 3.0 (285g). All models feature the same design and construction, but with different materials. Each of the five models has a dedicated sole color. The 1.0, for instance, is the neon greenish yellow.

The upper is generously vented

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