WTB Trailblazer 2.8: 27.5+ revolution?

20 10 2014

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…




13 responses

20 10 2014

Intrigued to see it set up.
The tape lip can only be a good thing I reckon.

20 10 2014

Need to do the tape thing to my Dually…

22 10 2014
Michael Schiller

don’t wanna sound like a detail freak… but Is the dia really 735mm? Everyone else reported 726ish. Asking to see if it will fit on my bike which has a tight clearance due to a 72 STA.

22 10 2014

not at all!… i’ll admit i did not measure the diameter of the tyre myself but lifted the diameter from another popular blog. the width *is* my own measurement. i took the rulers out this morning and sure enough the diameter is precisely 726mm at 14psi on a velocity p35 rim. thanks for pointing that out!…just goes to show….

22 10 2014
Michael Schiller

thanks. my grand plan is too have the builder of my filet brazed 29er replace the seat stays, which is the only area I’d have a problem with the B+ tires. After I should be able to fit the Vee at 3.25″

30 11 2014

Hi Jon, where did you get your 27.5 tyres from?

30 11 2014

Hi roger, I ordered it directly from the helpful folk at WTB while I was over in Portland. I have no idea how to get hold of one in the uk, and my understanding is they sold out in the USA- thorough some shops might have some? I think more are on the way

30 11 2014

Good answer! Thanks Jon.

3 12 2014

[…] the quality of the tyres makes a huge difference to the ride. my original thoughts on it are here: WTB Trailblazer 2.8: 27.5+ revolution? | drj0nswanderings WTB were ace to deal with, i phoned em up when i was over in Portland recently and 48 hrs later […]

20 01 2015

Cool blog Jon. An inordinate amount of my time is taken up thinking about breaking into the semi fat world and what bike to do it on. The Jones 29 steel diamond and unicrown fork is bike of the moment. Do you think the 27.5+ trick would work on that? I’m thinking Jones rather than krampus for tighter back end, lower BB, shorter WB. Rigid fork only. Do I really need bigger tyres than 2.4 on 29 P35 with a fat front option and/or mayb 27.5+?! It’s pretty confusing, without the means to test lots out. Which Non custom bike do you think would best suit the inspirational kind of wilderness riding & bike packing trips you like to do?

21 01 2015

andy! thanks! i have no doubt the 27.5+ would work well on the steel jones – the geo is exactly the same as mine!….the 27.5+ is a nice match for a 26×4 tyre at the front – very similar diameter. the true 29″ers are a little bigger, but would also do fine on the front. the geo is relaxed a bit with the 29+ front 27.5+ rear, and it rides really nice….i like all these set ups! the ebb allows you to mitigate the bb change with the 29 or 27.5+/26×4 diameter change pretty easily, as most folk seem to run the bb in the lowest position with 29ers as per jeffs general thoughts. 2.4 on a p35 is great….the difference in going to a plus tyre is probably of the order of 5-7 psi though – i run 9 in the chronicles and 11 in the trailblazer as opposed to 17 in a 2.5DHF maxx on 30mm rims or 20 ish psi in most other tyres, tubeless. that gives you some plushness that if you are doing rough/long rides removes some buzz and is IMO worth the weight. you cant get much better than the jones for non custom wilderness and bikepacking trips, the only caveat being it will weigh more than a disposable carpet fibre bike – the krampus is ace and bike packs well. but its a different beast! not a bad option at all, between the 2 id probably come down on the jones – particularly as 27.5+ offers a lot of what 29+ does, but the bike is overall tighter….in years to come id predict 27.5+ will eclipse 29+ though both will be available.

24 03 2015

Hi Jon,

Thanks for the info. What is the tyre/mud clearance like at the chainstay on your Jones 29, with a 27.5+ tyre on a wide rim? I like the wtb Scraper rim with a similar width to Dually so wondered if that would work in the winter muck. I’d probably run 27.5+ front and rear on this frameset. Do you think the EBB will provide enough BB height without the set up being compromised. I guess you still want it low but not as low as the 29 position.
Enjoy the spring weather!

25 03 2015

It’s good- I’d estimate 7mm. I think there is a pic not too far back on. My Flickr that shows it- hold on- http://flic.kr/p/qiokhU

I reckon with a vee 3.25 up front and a trIlblazer rear you’ll drop around a cm bb- a bit more if two trailblazers as the overall diameter is a bit less than a normal 29″ tyre. so if you are running the ebb downwards, rotating it will gain up to 12mm- mostly getting correct bb height back. The reduced drop changes the handling- I like like that, a wee bit less stable, so good in the messy stuff!

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