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The Pearl Izumi isoTransition is a nimble racing shoe for top-notch running. It offers minimal cushioning and a semi-firm ride.



When it comes to race day performance, the Pearl Izumi isoTransition is a top-notch performer. The quick-pull lacing system makes this racer easy to slip on. The seamless upper allows you to wear this shoe barefoot and offers drainage holes in the midsole to release fluid. Serious runners will love the low-to-the ground, responsive ride quality the isoTransition offers. The isoTransition makes a great triathlon or road-racing shoe.

Model Number:

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Weight: 7.9 oz (size 9)

Stack Height: Heel (21mm), Forefoot (11mm)

Available Widths: D=Medium

How It Fits (based on width D) 

  • Sizing: Standard running shoe length
  • Heel: Medium
  • Midfoot: Medium to full volume
  • Forefoot: Medium
  • Toe-Box Height: Medium to low
  • Arch Structure: Low
  • Shoe Shape: Semi-Curved



The isoTransition is a moderate feature, moderate neutral shoe designed for speedwork or racing.


  • 1:1 Energy Foam is located in the forefoot and is a responsive cushioning device that is designed for increased energy return.
  • EVA is an industry standard thermoplastic designed to provide durable cushioning.
  • TPU Bridge is located at the bottom of the midfoot and is a thermoplastic unit intended to maintain forefoot and rearfoot torsional integrity.
  • 1:1 Seamless Race Upper is designed to reduce irritation and improve next-to-foot comfort.
  • 1:1 Lacing consists of internal overlays specifically placed at the midfoot to keep the upper snug to the foot.
  • Ortholite Sockliner provides amazing step-in comfort and long-lasting cushioning.
  • Full Blown Rubber is utilized throughout the remaining outsole and is lightweight and flexible.
  • EVA Outsole is an industry standard thermoplastic designed to provide durable cushioning.

Footwear Performance Characteristics

Pronation Control: What's This?

  • Neutral
    • Min
    • Mod
  • Support
    • Min
    • Mod
    • Max
  • Motion Control
    • Mod
    • Max

Heel-Toe Offset (mm): What's This?

  • 0
  • 1-2
  • 3-4
  • 5-6
  • 7-8
  • 9-10
  • 11+

Stack Height:

  • Barefoot
  • Minimal
  • Low
  • Medium
  • High
  • Maximal


  • Road
  • Road-Trail
  • Hard Trail
  • Varied Trail
  • Soft Trail

Shoe Type:

  • Premium
  • Standard
  • Performance
  • Racing

Customer Reviews

Comments: In support of John's comment, I found these shoes much narrower than everything I have owned so far, from Adidas Adizero Rocket, Mizuno Wave Ronin 3, New Balance MR890.  My size ranges from 9.5 to 10 in other brands.  I ordered a 10.5 for these PI shoes and still had difficulty to get in, and found the shoes press too hard on the sides of my feet.  Will return and may try size 11 to see if they fit better.  Too bad because these shoes seem to be perfect for a race shoe or speed trainer.  I'm a male runner, 6'1, ~180 lbs, doing about 25-30M/wk.
From: Phuc, Potomac, MD, USA

Comments: I like the shoes, but tough to get into and in my opinion they run narrow. I wear a 10.5 and had to wear two pairs of thick socks, just to get my feet in comfortably. If you have narrow feet they should be fine, but it you tend to be snug in a D width, it may not be the shoe for you.
From: John, Spokane, WA

Comments: I have raced all season in these, got them the day they showed up here. It has some MUST have multi-sport shoe related attributes. 1) elastic no tongue sock liner allows for no sock needed 2) holes in the sole for water drainage when you dump a cup of water on yourself in a race 3) elastic laces for speed transitions 4) fairly light weight material for quick dry and weight savings. BUT, it has 2 downfalls.. 1) that pull tab on the rear is 100% worthless. You can't grab it nor put your finger through it to aid in pulling the shoe on quick. At least, not if you care about transitions measured in seconds. 2) that heel cup is the must f***** up design I have ever felt on a shoe. The heel is literally a hard plastic insert that has zero give. I get why it was done - keep the heel from collapsing in a fast transition - but DAMN was a hard plastic insert actually needed?  I will take flexible heel cup any day with the risk of collapse in T1 over that plastic cup. That cup destroyed my heel - bloody blister the size of a quarter - on first run that took weeks to heal. Now I am okay, but lordy. In these 2 respects Zoot does it better but Zoot's just fall apart so quick.
From: Anonymous

Comments: Far more superior in fit and function than any Zoot offering.  The laces actually function in this shoe.  I have experienced no irritation what-so-ever without socks which is more than I can say about Zoot's offerings.  Incidentally, Zoot's 2012 line-up will feature lower heel tabs throughout as a result of frequent achilles rubbing.  The Pearl's foothold is exceptional, entry is a breeze, and the low to ground midsole height offers great stability and feel for the road.  Hands down, the best triathlon race shoe I've tried.
From: Anonymous

Comments: I have the Streak II's and these shoes are just as good. From a 4 mile tempo to a long run. These shoes fly. I went 16 miles today in these and I am 6', 185lb. No issues we these shoes. They push you forward on your toes. Great shoes!!
From: Kevin, Roseville, California, USA