Pearl Izumi X-Project Shoes

by Brian Mullin on November 7, 2012

Mountain biking shoes are an oddity, since they are asked to perform multiple functions, including offering a stiff platform for optimal power transfer to the pedals and walkability for off the bike forays. The sports apparel and footwear company Pearl Izumi wanted to meld the benefits of pedaling and walking performance, so they designed the new X Project mountain biking shoes by starting from a clean blank slate, which allowed them to look at things from a unique and different perspective. By using innovation and biomechanical engineering and partnering with established Italian shoe artisans, they designed features into them that made sense for off-road functionality, so that the shoe would pedal and hike, with no performance loss for either endeavor.

In a nutshell, the X Project shoe uses a tuned carbon sole which is rigid while pedaling and then will flex when hiking or running over technical terrain. The shoes have an EVA foam heel to absorb impact, Co-molded rubber tips on TPU lugs for traction, and a full-length tapered unidirectional carbon plate for power transfer and hike-ability.

X Project Press Camp
Pearl Izumi held an X Project press camp in Laguna Beach California at the rustic Aliso Creek Inn and Golf Course, which is nestled in the lovely Aliso Canyon. They invited editors and writers from around the country to participate in a show and tell of the new shoes, and to get a hands-on experience riding and hiking the shoes around the local trails with Brian Lopes as a guide. Test bikes were provided by the great Pivot Cycles Demo team, and the trip coordination was organized by Outside PR.

The X Project program was run under the auspices of Pearl Izumi’s cycling shoe manager Tony Torrance over a two-year time frame, with extensive design input from the four-time world mountain bike champion Brian Lopes, and coordination from Italian shoe and carbon composite’s craftsman, and CSU’s Human Performance lab.

Their X-ALP series was the precursor to the X Project shoes, and instead of the X-ALP’s more recreational and hike-a-bike orientation, they focused on a shoe which was lightweight and aligned for performance and racing, yet retained enough flexibility for hiking.

The shoes come in three models, the top of the line uni-sex X Project 1.0 ($280), and the men’s X Project 2.0 ($210) and X Project 3.0 ($160), which come in vivid green, orange and red colors, respectively. They have a women’s specific version in the X Project 2.0 ($210) and X Project 3.0 ($160) models, which has a corresponding anatomical last, and comes in purple and blue colors, respectively. All the shoes have the exact same performance and power characteristics, and there are just fewer features, increased weight and decreased cost as you move down the model lineup, and they’ll be available in the March 2013 time frame.

The obvious highlight of any of the X Project shoes is their brightly colored translucent soles. The 1.0 uses a combination of TPU and mesh materials, which makes it light at 320 grams and provide proper ventilation, so it would suit warmer conditions, while the 2.0 use of synthetic leather would work better in wet and colder environments, and the 3.0 uses a mixture of synthetics and mesh.

Uppers
They use a fully bonded composite upper construction which is commonly used in running footwear. It has the strength of traditional synthetics that are perforated, but gets the breathability and weight savings by using a single-layer mesh (like a running shoe) and bonding a TPU (thermoplastic polyurethane) skin with a synthetic underneath. This unique three-layer construction has a high strength to weight ratio, with excellent suppleness and breathability. The 2.0 and 3.0 use synthetic leather

The 1.0 features their padded and fully featured P.R.O. Micro-Adjustable buckle, which has a low profile, and three side locations for instep height adjustment. The buckle has a long throw lever adjuster arm and push button release for on the fly adjustments, both of which are incredibly easy to use. The 2.0 and 3.0 models use their more typical buckle closure system.

The two lower straps are canted 25 degrees back to follow the natural contours toward the lateral side of the foot to help with hot spots and blisters. The well-padded tongue uses an SPR foam (open cell) which is very dense and doesn’t absorb water, and gives good cushioning and protection to help with pressure spots.

The 1.0 and 2.0 use their semi-custom 1:1 insole system, which has some mild orthotics and includes a metatarsal pad and adjustment wedges for the arch and varus in the forefoot. The 3.0 model has an insole that only has a metatarsal pad.

Sole
In the words of Pearl Izumi, the magic of the shoe is the sole! Their goal for the sole of the shoe was flexibility in the toe section for hiking up steep slopes, and lateral stiffness under the pedal interface for power transfer, with torsional flexibility and pliability in the rear portion for nice purchase on uneven terrain.

To come up with the ideal sole, they did great VO2 and power transfer testing at CSU’s Physical Activity Energetics/Mechanics Lab (PAL) under Dr. Ray Browning over a year-long process, testing and removing material from the sole to see how performance changed. They cross compared these parameters against their race shoes and the competitions so that they had a good barometer of things.

A crucial aspect of the sole was their partnership with Italian shoe manufacturers, who have expertise in carbon fiber, co-molding, TPU, and lugs. The craftsmanship and knowledge base of the Italian artisans are beyond reproach, and no one else in the world can match their shoe wizardly and understanding.

They went through many iterations of the sole’s carbon plate size and length and shape to get optimal stiffness with as little material as required, and it turned out that the rear and toe portion didn’t need as much as under the pedal interface. After finding where material was necessary longitudinally, they started on the layering geometry of the carbon plate. There is lots of tuned layering with unidirectional as well as woven carbon fiber under the pedal interface, and then tapered construction as you move away from pedal area into a sheet carbon and TPU under the heel and forefoot. It’s very complex how the tapering happens between the layers from one end to the other, especially since abrupt or sharp transitions would cause issues, such as weak spots, so it needs to be done gradually. The front of the shoes has more layers than the rear, while the pedal interface has the greatest amount.

The 1.0 and 2.0 use the same carbon fiber construction on the sole, while the 3.0 uses more of a glass fiber layup, although the end performance characteristics are the same for all models.

Instead of using TPU lugs for the rubber tips, which have a weak grip, they decided to go with a system which is more commonly used on high end Italian mountaineering boots. Many mountain bike race and high-end performance shoes tend to slip around on rocky surfaces and roots, and you feel like your “Skating Away on the Thin Ice of a New Day.”  The X Project uses co-molded and injected carbon rubber tips, which have excellent durability and grip, and no delaminating or peeling issues. Under the lugs, as much material as possible is cored out of the TPU frame to save weight, without degrading performance, strength and durability. They use an EVA foam in the heel, which has been co-molded, and offers a good job of absorbing impact and distributing it across the heel instead of up into the body.

First Impressions
At the press camp, Brian Lopes took us out on some uber steep dirt hike-a-bike trails, so we got a very good idea of how the X Project 1.0 shoe felt while walking. The toe section had a nice flex up towards the end, though they didn’t feel as flexible during hiking as their Alp-X Elite shoes. I did like the pliability in the rear, as it made the shoe conform to the trail’s slope, which was especially evident when side stepping. I did notice a slight amount of heel lift, though it seems to have lessened with a break-in period over the last week or so during mu post usage. When pedaling, the shoe had excellent power transfer, and felt as stiff as any race shoe I have used. When you’re on the pedals, I didn’t notice the slight flex in the rear of the shoe, or else it just blended into the comfort and usability. The toe box is snug, but it wasn’t narrow enough to cause any pinching or discomfort issues, though after a long day in the saddle with swelled up feet it might become an issue? I really liked the P.R.O buckle system, which had an excellent release button and an easy to use lever adjuster, which made on the fly tuning incredibly simple.

Overall, I was mighty impressed with the shoe, as it let me get off the bike and hike around with comfort and safety, and still gave me impressive power to the pedals. It was comfortable, had a semi-custom insole, an excellent buckle system, grippy lugs, and was a good for hiking and excellent for pedaling. If you do extensive hiking, you’ll want their X-Alp series shoes, but you’ll lose the power transfer characteristics of the X Project.

Pros

  • Excellent power transfer
  • Good hiker
  • Comfortable
  • Light – 320 grams
  • Semi-custom insole
  • Grippy lugs
  • Excellent buckle on 1.0

Cons

  • Heel lift
  • Width is slightly narrow
  • Not a pure hike-a-bike shoe – look to the X-Alp series
  • Expensive

 

 

X PROJECT 1.0 Specs
The X PROJECT 1.0 is the pinnacle of the X PROJECT line that features a uniquely constructed sole that is flexible in the right places for hiking or running, but as efficient as a fully rigid carbon bottom. A patent-pending carbon plate provides optimal power transfer for the best of both worlds. It’s a perfect shoe for mountain bikers and cyclocross racers alike.

  • MSRP: $280
  • Sizing: 38-47 in ½ sizes, 48, 49
  • Weight: 320g
  • Fully bonded upper construction provides lightweight breathability
  • 1:1 patented anatomic P.R.O. Buckle system features a 25-degree angled strap design that follows the anatomic curve of the foot
  • Seamless construction in the toe area for no-seam comfort in the flex zone
  • Run shoe EVA foam heel absorbs impact for off-the-bike comfort
  • Full-length tapered unidirectional carbon fiber plate (patent-pending) gives on-the bike power transfer and off-the-bike hike-ability
  • Co-molded rubber tips on hollow TPU lugs provide traction on an extremely lightweight bottom unit
  • Includes 1:1 Insole System with Total Tune Performance Inserts

X PROJECT 2.0 Specs
The X PROJECT 2.0 is the ultimate shoe for mountain bikers because its unique design provides pedaling efficiency with hiking and running performance. A patent-pending carbon plate provides optimal power transfer for the best of both worlds. A perfect shoe for mountain bikers or cyclocross racers

  • MSRP: $210
  • Sizing: Men’s 39-47 in ½ sizes, 48, 49 and Women’s 36-43 in ½ sizes
  • Weight: Men’s 325g and Women’s 280g
  • 1:1 anatomic buckle closure features a 25-degree angled strap design that follows the anatomic curve of the foot
  • Seamless construction in the toe area for no-seam comfort in the flex zone
  • Run shoe EVA foam heel absorbs impact for off-the-bike comfort
  • Full-length tapered unidirectional carbon fiber plate (patent-pending) gives on-the-bike power transfer and off-the-bike hike-ability
  • Co-molded rubber tips on hollow TPU lugs provide traction on an extremely lightweight bottom unit
  • Includes 1:1 Insole System with Total Tune Performance Inserts

X PROJECT 3.0 Specs
The X PROJECT 3.0 is a brand new type of cycling shoe. Maximum pedaling performance combined with hike-ability make this the perfect solution for mountain bikers and cyclocross racers alike.

  • MSRP: $160
  • Sizing: Men’s 39-47 in ½ sizes, 48, 49 and Women’s 36-43 in ½ sizes
  • Weight: Men’s 330g and Women’s 285g
  • 1:1 anatomic buckle closure features a 25-degree angled strap design that follows the anatomic curve of the foot
  • Seamless construction in the toe area for no-seam comfort in the flex zone
  • Run shoe EVA foam heel absorbs impact for off-the-bike comfort
  • Full-length tapered carbon-composite unidirectional plate (patentpending) gives on-the-bike power transfer and off-the-bike hike-ability
  • Co-molded rubber tips on hollow TPU lugs provide traction on an extremely lightweight bottom unit

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