First Ride: Pearl Izumi flex-sole X-Project mountain bike shoes

Power-transfer lab tests allow Pearl Izumi to develop a shoe stiff enough for performance with flex for walking and running your bike

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The Lowdown: A super lightweight performance mountain bike shoe with a tapered carbon sole and rubber grip. The idea is that you can walk and run your bike in them as well as you can ride your bike in them.
Pros: Lightweight, grippy, stiff where power transfer is most important and flexible where it can be spared with shock-absorbing foam in the heel
Cons: The rubber grip started to peel off the lugs by the end of the day

That’s right, these performance mountain bike shoes were made for walking.

With its new mountain bike shoe, Pearl Izumi set out to create a shoe that satisfies the demands of stiffness for performance, but is designed with the hike-a-bike in mind, with attention to flex, traction and shock absorption for the time spent walking and running with your bike.

To create the X-Project shoe, the Pearl Izumi engineering team lab tested road shoes with the stiff plates in the soles partially removed to see which points transfer the most power. From that information, Pearl Izumi’s development team discerned where a shoe can be allowed to flex without sacrificing power.

Pearl’s solution was a tapered carbon sole, fully rigid where power transfer is the most crucial for performance, but flexible under the toes where you can afford to have some flex, to make them more comfortable for walking and running.

According to Pearl Izumi, lab tests showed that the tapered soles were as efficient as road shoes, despite their flex.

“We tested with motion-tracking equipment and oxygen-consumption equipment to find that the shoe is as efficient as any fully carbon road shoe or a fully carbon mountain bike shoe,” said Pearl Izumi cycling footwear manager Tony Torrance.

Four-time world champion Brian Lopes was involved in the development of the X-Project and put a prototype to the test in the short-format World Cup Cross-Country Eliminator in Houffalize, Belgium, which he won.

“[It’s] a discipline that really requires explosive power out of the start and full-on sprinting start-to-finish, so it was pretty cool to have the first prototype and take it to a victory right out of the gates,” said Lopes.

When I first pulled the X-Project on, the sensation was unusual, because they flex farther toward the toe than most MTB shoes. The flex is very noticeable and articulates forward of the ball of the foot. I kept them on all day, however, and over the course of seven hours spent on and off the bike I got used to the sensation and quickly didn’t notice it any longer. I have no doubt that I would prefer that to walking around all day in stiff mountain bike shoes. If anything, the walking became more comfortable throughout the day.

The second key feature of these shoes is the rubber-tipped lugs. The black rubber grip is integrated into the neon sole.

While wearing the shoes around, I scrambled up steep rocks and loose gravel, and found that they gripped rocks like a gecko’s feet grips to a window, even with cleats. Between the deep tread, grippy rubber and spike mounts, I would imagine these shoes could tackle almost any terrain. They would certainly shine walking on slickrock.

By the end of the day, the black rubber did start to peel away from the TPU sole in one place.

The final key feature is the EVA heel. Pearl Izumi uses shock-absorbing foam, similar to the material used in running shoes, to provide relief for long days of hiking.

Shoe fit is, of course, particular to each rider. After wearing the X-Project all day, I was certainly getting uncomfortable, but I was definitely impressed by the fact that I could stand to spend a seven-hour day in mountain bike shoes that I hadn’t broken in. They fit very differently than my Sidi mountain bike shoes, but no less comfortably. The heel was more snug on the X-project, as was the outside of the foot.

At around 325g per shoe, the X-Project could set the bar for lightweight performance mountain bike shoes in any dirt discipline that requires slogging, and if Lopes could win a World Cup on them, they might shine just as brightly, even if you never have to dismount.

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Emily spent her infancy in the back of a women’s team van while the team built wheels around her. She spent part of her pre-teen years in Europe following the major European mountain, road and gravity races and touring cycling product factories. College was the first time she lived in a home without a frame building shop in her garage or basement. Her favorite style of riding is getting lost in singletrack trail networks and taking her time finding her way back.

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