Despite some folk bemoaning the introduction of yet another tyre size, the 27.5+ makes all sorts of sense.
For starters, a 27.5×2.8 tyre such as this one, the WTB Trailblazer, fits in the rear of a 29″er that has reasonable clearance. “So what?” I hear you cry. Width on my 35mm Velocity rim (tubeless) is 68mm and the diameter is 726mm – in other words, a wee bit less than a full blown 29″er, in order to keep the widest point of the tyre further back in the chainstays.
[NB: I had previously noted the diameter as ‘right around 735mm’ – after a prompt from Michael, see comments, I measured this accurately and the diameter at 14psi on the 35mm velocity rim, tubeless is 726mm…it just goes to show, always measure yourself if you want to be sure! – thanks Michael].
The benefit is you get some of the advantages of a semi-fat tyre (improved traction, lower pressure, better ‘float’) without having to get all weird building a custom bike with a yoke or fat-bike wide bottom bracket and rear hub: it should slot into many 29″er frames with minimal fuss. The only thing to consider is a slight drop in BB and slackening of angles if only the rear is retrofitted.
My suspicion is that there will be several 27.5+ tyres along forthwith and my guess is they will in some cases be larger than the Trailblazer from WTB, in some cases the same. Rumour is that the Vee 27.5+ tyre (the Trax Fatty) is a full 75mm+ wide and will not fit most 29″er frames. There are whispers of Bontrager and Panaracer 27.5+ tyres and another WTB in the pipeline too.
How does it ride?
Really well. Much better edge than a Knard and it gives up little in terms of the float/low pressure (I was running it at 14 psi and will probably drop it one or two). I was riding in slop today and I hardly ever lost traction despite the centre ridge being almost complete and the other knobs being not that burly. You don’t get the insane roll-over-ability of the huge 29+ wheels (which are near 770mm in diameter), but the low pressure helps maintain progress in rocky, chunky terrain. The compound seems good – minimal slip on wet, mossy rock and roots. and the tubless set up was a treat – TCS is good. It is not über light at 950 and some grams, but the sidewall is solid which is a good thing.
More time is required to see where this is going, but I like it so far. Most folk are going to comapare these to fat bikes and 29+ knards, I suppose, and I think that comparison leaves the Trailblazer in a favourable light.
As WTB say: Big Kid Shreddin’ / Plus Sized Grinnin’
As an aside. I set up the Velocity 35mm rim with a bead seat shelf augmented with a Gorilla tape lip after a discussion with davechopoptions. It worked surprisingly well…and we will see if prevents burps.
…and after a final layer of tape…you can just make out the extra ridge…