Mountain biking inevitably involves at least some walking. Be it a quick dab, walking an uncomfortably technical stretch, or scrambling up an impossibly steep climb to reach the singletrack above, many of the best trail rides include at least a bit of hiking. With that in mind, Pearl Izumi asked themselves if it would be possible to create a race-weight, trail-ready riding shoe that was stable and comfortable off the bike while maintaining race shoe stiffness in the pedals.
Two years later and after drawing on experts from three continents, they feel that the answer is “yes.” And they invited a number of journalists to Laguna, California for some riding and pushing to prove it. Hit the jump to find out more.
Pearl Izumi worked with four-time world mountain bike champion Brian Lopes, Italian composites and footwear manufacturers, their parent company Shimano, and Colorado State University to meet their goal of designing “a shoe that hikes and runs just as well as it pedals.” Soft launched at Interbike this fall, the 5-model X Project line of shoes is the result.
Pearl Izumi’s last effort at an on/off bike trail shoe was the X-Alp series. Somewhat chunky and biased more toward walking than riding, the X-Alp is more of an “all mountain” shoe that isn’t quite at home on long bike rides. The X Project line approaches the problem from another direction- and its race shoe roots are clear. Working with physiologists at CSU’s Human Performance Lab, the X Project team measured rider output and VO2 Max as they removed more and more of the carbon fiber plate that made up the sole. The results surprised even Pearl Izumi: by mid-arch any added stiffness is largely wasted. Similarly, little stiffness is needed ahead of the cleat.
The result, as can be seen here, is a carbon fiber plate that is at its thickest under the ball of the foot and tapers both in width and stiffness toward the front and back of the shoe. The tapered width allows for a bit of torsional flex between the forefoot and heel, allowing the shoe to better follow rough ground. The translucent TPU outsole sole just plain looks cool and shows off the carbon.
Working with an unnamed Italian mountaineering footwear company, Pearl Izumi developed an extensively lightened outsole (seen at right) with every bit of unnecessary material cored out to reduce weight. In order to provide better grip than most mountain bike shoes, the Italian boot maker helped Pearl develop a co-injected rubber tread that would actually last. Getting the tread-sole interface correct is so critical and requires enough proprietary technology, that the outsoles are made in Italy before being shipped to one of Pearl Izumi’s Asian factories for final assembly.
Similarly, getting the carbon fiber sole plate to flex to allow easy walking while still remaining efficient is no easy task. To tackle that effort, Pearl Izumi employed the carbon genius of a composite supplier to Ferrari, Ducati, Luxottica, and unspecified Formula 1 teams. Needless to say, they know carbon. The 1.0 and 2.0 level shoes share the same carbon plate while the 3.0 retains the same stiffness and flex properties, but from a slightly heavier (but less expensive) glass composite mix.
Other features include anatomically-designed 25° backswept straps (the top with Pearl Izumi’s clever three-position anchor) and a shock-absorbing EVA foam heel pad borrowed from the company’s running line. A dense, perforated closed-cell foam tongue is designed to remain comfortable without becoming hot or retaining moisture after stream crossings. The X Project line consists of five models: one unisex and two each for men and women:
X Project 1.0 Unisex, $280
- A fully bonded 3-layer upper that seamlessly transitions from scuff-resistant to open mesh areas
- An Italian-sourced micro-adjust low-profile buckle on the top strap
- Includes Pearl Izumi’s 1:1 Insole System, which feature interchangeable Total Tune Performance cant and arch support inserts
- Green outsole and graphics
- 280g weight
X Project 2.0 Men’s and Women’s, $210
- A seamless microfiber upper with perforated vents that is slightly heavier but more scuff-resistant than the 1.0’s bonded construction, with seam free toe box and reinforced toe
- Pearl Izumi’s standard top strap ratchet
- Includes Pearl Izumi’s 1:1 Static Insole System, which offers 1:1 fit geometry, without the customization
- Orange (men’s) or purple (women’s) outsole and graphics
- 325g (men’s), 280g (women’s)
X Project 3.0 Men’s and Women’s, $160
- Standard stitched construction with seamless toe area
- Pearl Izumi’s standard top strap ratchet
- More cost-effective glass composite sole plate with the same performance as 1.0 and 2.0 levels
- Dual-density insole
- Red (men’s) or teal (women’s) outsole and graphics
- 330g (men’s), 285g (women’s)
Revised slightly since their Interbike launch, the X Project 1.0s came straight from the factory to our press camp with only hours to spare. The sizing now seems a smidge bigger and the upper no longer bunches like it did at Interbike. Brian Lopes, who played a big part in the shoes’ development, and the Pearl Izumi team took us on a group of Laguna-area trails chosen to highlight the shoes’ on- and off-bike performance. (Locals groaned audibly when told they’d be climbing a trail called “Mentally Sensitive.”) Sure enough, the entire group was making the most of the soles’ stiffness while pedaling up the walls of Wood Canyon- and soon thereafter taking advantage of the soles’ flex and grippy tread while pushing up steep and technical sections. Not a trail any of us would have chosen race shoes for.
Because half-size molds are still not complete (the shoes will be available in early March, 2013), it was hard for one of our writers to get a great fit in any one shoe. That said, the shoes’ stiffness on the bike felt on-par with even Specialized’s S-Works Evo shoes. Off the bike, the mountaineering rubber was very grippy and, combined with the soles’ tuned flex, very confidence inspiring (and not at all bike-shoe-like)- even in our host inn’s parking lot. The tapered carbon fiber plate made the flex feel quite natural, without any sharp transitions or folds. Breathability was good and the straps felt well placed.
On steep climbs, fast rolling trails, and technical descents, the shoes never felt out of their depth. All of these things suggest that Pearl Izumi have achieved their goals and created a shoe that racers, ‘big day out’ trail riders, anyone faced with a cruel LeMans race start, cyclo tourers, and cyclocross riders could appreciate.
The only possible yellow flag (shared by both of our writers and most other attendees) was the microfiber (synthetic leather) heel cup. Like older Shimano shoes, the smooth fabric allows for a good deal of heel lift while hiking extremely steep sections- even on too-small shoes. Presumably, however, that material choice will also improve durability and reduce the likelihood of blisters when faced with long walking sections. In any case, it doesn’t seem to be a problem on less-steep climbs and was less of an issue later and on subsequent rides- making us wonder if it was a break in issue or just different. With only twelve hours in the Pearls between two riders, it’s too early to say. We’ll try to wrangle a 43.5 for longer-term testing and report back before the X Project becomes available.