Interbike Mtbr

WTB Trailblazer tire - Scraper rim

WTB's new Trailblazer tire comes in a diameter called 27.5+ (say "twenty seven-plus") that's a huge 2.8-inches wide.

"You've got to be kidding," is the universal response when told WTB has introduced yet another wheel and tire standard to the increasingly complex rubber and rim mountain bike universe that includes 26-, 27.5-, and 29-inch rolling stock, not to mention some bovine versions thereof in the fatbike universe.

But before you get your chamois in a wad, consider that the new 27.5+ (pronounced "twenty seven-plus") standard is actually made to fit on existing 29-inch bikes. Though the rim diameter is 27.5-inches, the 27+ tire is extra wide and extra tall, with a sidewall height that puts its outer diameter level with a standard 29.

Why, you might ask, would someone put such wheels on a 29er when they already have perfectly good 29-inch hoops and tires? Apparently some adventure bike-types wanted some of the benefits of fatbikes--more float, traction and bump absorption--but without the full-on commitment or heft of a dedicated fatty. Ostensibly, two wheelsets--one a 27.5+ and one a 29er--gives you two bikes in one.

WTB started toying with the idea and once they proved a few things out, Rocky Mountain Bicycles got involved and kicked the idea around.

Rocky Mountain's Sherpa is shown here with 27.5+ tires, but it can also roll on 29-inch wheels.

At the Sea Otter Classic race in April, Rocky Mountain showed a prototype bike called the Sherpa made from the standard front end of their Element 970 and a slightly widened rear end, making the bike suitable for either standard 29er wheels or 27.5+. WTB went on to fit the wheels to a number of other bikes and found they could do so without the modded rear end.

"The Trailblazer is a 27.5 x 2.8-inch tire with an overall diameter of the tire is about 28.6inches, very close to a standard 29" tire," explained WTB Marketing Manager Will Ritchie. "As a result, you can take it and fit it in an existing 29er frame or bike without having to do any custom retro fits. You don't need a new fork, it can fit comfortably within the chainstays of most current 29 inch hardtail or full suspension bikes."

That as the background, WTB intrduced production versions of the 895-gram Trailblazer which use the company's familiar Dual DNA fast rolling compound and TCS Light tubeless casing. WTB recommends the tire be used on rims with an internal width of 25mm or more.Tralblazers go for $67.95 each and are available now.

At a whopping 45mm wide, WTB's Scraper i45 rims with a 45mm internal and 50mm external width certainly qualify as Trailblazer-capable. Available as a rim only, the $150 Scraper i45 will be available in November with a 29+ version following in early 2015.

Some Mtbr readers have asked:
Q - Will the Trailblazer tires fit on standard 27.5 rims, or do you recommend the extra-wide Scraper rim only?
A - "The Trailblazer will work with a number of rims out there and, yes, it is a traditional 27.5-inch rim we're talking here. We've had success with our Frequency i25 (25mm internal rim width) 27.5-inch TCS Team rim, though the profile becomes more rounded and less wide. We'd recommend this size--25mm internal--and wider. There are many rims out there that fall within the WTB Frequency i25 and spacious 45mm internal WTB Scraper i45 27.5-inch TCS rim." - WTB Marketing Manager Will Ritchie


This WTB-provided illustration shows the difference between a 27.5+ tire within a traditional 29er dropout and a 29+ tire within that same dropout.So when you're looking at the diagram, the tire on the left is the WTB Trailblazer 2.8 x 27.5-inch TCS Light tire, while the tire on the right would be a theoretical 2.8 x 29-inch tire attempting to fit within the same dropout.

Though they don't yet have a list of compatible bikes, WTB says they will be compiling a list soon, so riders looking to give their 29er another personality will know if the Trailblazer/Scraper combo works for them.

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This article is part of Mtbr's coverage of the 2014 Interbike trade show in Las Vegas. For more from Interbike CLICK HERE.