WTB Trailblazer 27.5 X 2.8″ Tires: Exclusive B+ Review Intro- by c_g

Trailblazer B+

An OS Bikes Blackbuck with the Trailblazer 2.8″ B+ tires

Editor’s Note: We’ve been aware of the so-called “B+” concept for a few years now. It takes the idea of fat bikes, 29+, and your standard 29″er and fits it all together on a 27.5″ rim which comes out to be just shy of 29″ in diameter. Confused? Don’t be. The crew of TNI.com has their hands on the first samples given to any media to help you understand this concept. Here we have our German contributor, c_g, who has already been riding these wheels for several weeks now on trails, with his report on the concept of B+. Later on, Guitar Ted will also be bringing you more as he reports on the Trailblazer 27.5″ X 2.8″ tires which he will also be reviewing.

It is not too long since we have introduced you to the new B+ format (here).. Based on standard 27.5“ rims, but with particularly wide rims, the B+ concept by WTB, , with the intellectual father being Bob Poor, is designed to convert most 29“er bikes into „Semi–Fatbikes“ (my wording, not theirs :)) – no matter if it is a hard tail or a full suspension bike. . Ever since I have been wondering how that may ride.

Scraper rim

WTB Trailblazer 2.8 TCS on a WTB Scraper rim

Now we will find out as we have the grand opportunity to ride a set of new WTB Trailblazer 2.8 TCS tires – even before its official debut at either Eurobike or Interbike’14 and as one of the first free testers. When receiving the first samples I had the opportunity o check for compatibility of B+ with existing 29er frames..


Trailblazer 2.8

WTB Trailblazer in direct comparison on both rims – the Frequency I25 on the rear and the new 45mm wide WTB Scraper on the front of my bike.

Curious with how much fat bike feeling could be hidden within B+, I immediately took the wheels with the SCRAPER rims (inner width: 45mm!!) and stuffed them on my bike … or better tried. As it appeared there was a reason, why the ROCKY MOUNTAIN Sherpa adventure bike study (featuring the identical rim and tire combo) had a redesigned rear end – because every of my 29″er bikes was simply too tight, by a little only, but still. So before it even began, I buried the idea of riding the fattest possible combo and went for the I25 rim on the rear. On the front, though the Scraper /Trailblazer combo was no issue. I have tried every 29er fork within my reach (FOX 32 and 34, ROCK SHOX Pike and MAGURA TS8R) and there was no problem with either of them.


Trailblazer 2.8″ tires on Scraper 45mm rim (R) and i25 rim (L)


So, as it seems the B+’s compatibility with existing 29“er rear ends is largely dependent on rim width. The extremely wide Scraper rim blows up that Trailblazer tire to a size, that is likely a bit too wide for most 29er frames. On the i25 in contrast, the tire clearance is really huge. Given the fact, that this combo even fits an (unaltered)) OS BIKES Blackbuck, , a bike not known for its ample tire clearance, I dare to guess, that B+ will fit most 29“er frames, that have at least the tire clearance for an average 2.2“ tire …. depending on rim width.

–> In summary, I can confirm, that B+ does not require any special frame or fork, Just take the 29“er you already own – on the front with no limitations at all (if you like even with very wide rims), and on the rear you can pick whatever rim width allows the combo to still fit the frame. A clear advantage over 29+, where the 3“ wide tires won’t fit much anywhere but dedicated frames (or fat bikes)

For the initial review phase I have opted for the widest combo that would fit my bikes, meaning a WTB Scraper wheel on the front and i25 on the rear, both mounted on my CUBE Stereo. Wouldn’t it be cool to get a semi–fat bike with lots of travel (160mm front and 140mm back) this way. We shall see. Optically I really like the result already.

Now to sum up the review intro a few measurements and specifications of the WTB Trailblazer 2.8 TCS tires and the corresponding 27.5“ wheels:

Weights and Widths: The WTB Trailblazer 2.8 tires all came around 900g. The pre–production samples came in at 892 and 912g. . On the Frequency i25 rims it has a casing width of 64mm, , on the wider Scraper it comes out at a full 71mm. . So the width of 2,8“ actually is achieved on the 45 mm wide rims – not really fat bike level yet, , but it goes in the right direction. On the side: the tread is a fairly narrow 58mm wide. . So the casing extends well beyond the protective shield of the tread rubber.

Wheel weights were as follows – the i25 wheels come in at 905g for the front and 980g for the rear wheel. . The identical wheel set (same hubs and spokes) with the Scraper comes out at exactly 240g weigh penalty. So there is an additional weight of about 120 g between the WTB Frequency i25 and the WTB Scraper – an estimated rim weight of about 640g. Not bad for a rim that wide and designed to handle hard riding..


Trailblazer 2.8

Size comparison between the WTB Trailblazer 2.8 TCS on a WTB Frequency i25 rim (left) and a WTB Vigilante on AMERICAN CLASSIC Wide Lightening 29“er frames, one of the largest 29“er tire and rim combos – the difference in diameter is a mere 2 cm.

In casing height the Trailblazer comes out at 62mm. So the diameter of B+ is only marginally smaller, than a standard sized 29er wheel, but the difference translates also directly into a lower bottom bracket and a different distance covered per wheel rotation but I suspect the differences to be small on the trail. We will see.

Tubeless–Performance: Another important feature – tires and rims here come from the same manufacturer and it is obvious that WTB have done their homework on both. Mounting and inflation has been simply superb and WTB’’s TCS once more proved to be very good, simple to use and secure. And that applies to the narrower Frequency i25 as well as the Scraper rims. . Perfect score in terms of tubeless performance.

Stay tuned for our first impressions on WTB’’s B+ system and this much can be said already – there is a lot more to it then we would have thought at first. BIG FUN!!