Friday, May 12, 2017

Bontrager Gnarwhal B Fat tire.

27.5 x 4.5" is a lotta tire on the front of any bike.

I have ridden and loved this tire in winter, on hardpacked snow and ice.  It is so surefooted, so confidence inspiring, that it's hard to imagine a tire I'd want to ride more in those conditions.

That said, those conditions don't come around very often.  Now that I have Mastodon on the front of my Fatillac I can't help but to install any and every obese tire to see what it brings to the table.

I've done a handful of rides now with the bike set up as such.  Roughly 10psi in each tire -- apropos given that I'm largely riding tech trail and not soft surfaces with it.  Could probably drop as low as 8 up front without appreciable self-steer, and I've ridden it down to ~2.5 on a wider rim, on snow.

I don't know the exact difference in weight between the Gnarwhal and the B Fat (~3.5") Hodag that was on there previously, but I'd guess close to 8oz.  Numbers aside I can immediately tell that an increase has happened: the bike just wants to go straight, and the faster you're going the more this is so.

No real surprise there -- gyroscopic inertia and all that.

And the traction?  Sheeeee-it.  It's stupid, in a word.  Blow a line and it doesn't notice.  Deliberately leave the trail to ride chunky wash, wallride a slab, descend a pourover -- it just eats it up and farts out a creative blend of silt, sandstone dust, and bentonite crumbs as if to say "more please".

Again -- no real surprise there, given the massive air volume and massive square edged blocks.

All that said, the word that comes to mind over and over as I ride this tire is "overkill".  It's fun to have a tire creating incessant easy-button situations for you, but at some point you realize that the added mass and lack of need for input are removing some of the challenge of riding.  And I know that challenge isn't IMBA-approved these days, but that doesn't mean I don't crave it anyway.

Conclusion: Awesome tire for snow and ice.  Awesome tire for off-piste 3-season riding.  Massive overkill for a rider with any level of skill beyond "IMBA Expert", which is somewhat similar to "Owned my first bike for 2 whole months now...".

Don't hesitate with questions.


  1. I have a 2015 Trek Farley 6 with 26x3.8 Hodags (it doesn't take anything much wider), the rear tyre is looking worn and I'm wondering whether to replace it with another Hodag or the Gnarwhal. Trek list the latter as a more aggressive tyre although most information I can find on it is for studded use, I primarily ride on natural trails in the winter which are muddy and slippy but rarely snow. I see you've ridden the Hodag as well, I'm wondering what your thoughts are on Gnarwhal over the Hodag for wet, muddy and slippy conditions?

    1. The only way the Hodag could be better is if it were a function of collecting sticky mud, and then, since the Hodag is smaller, it would pack up less.

      Otherwise, the Gnarwhal is so much bigger, and so much more aggressively knobbed, that I think I'd almost always prefer it when things were slippery.

  2. I have been certain that I will have a large tire for deep (as i dare) snow. That pair of tires has been Bud/Bud in my mind prob on 100's. But... now that this is available, how would you compare the Gnarwhal 4.5 to Bud for snow?

    I weigh 155# and ride primarily in the NorthEast. Lot's of lake effect snow but sometimes we get the dry stuff too.

  3. Built up my new Nextie 85 mm finally...I paired the 27.5 Gnar front-fitted with the new 27.5 x 4.0 Van Helga rear-fitted. Live in Phx desert area...luv'n the new exploration opportunities on sloppy, loose, horse-trail, singletrack, and the connected deep, sand washes...wish the Gnar fit in back too but, the knobs rub...the VH is high volume tire...very supple ride. PSI:Front 7/Rear 10. I scale-in as a clyde 265 lbs with no self-steering issues, but have 4" DYI closed-cell inserts, so I'm sure that their space-fiiing properties assist with maneuvering/cornering while achieving decent float! BiiiG FUN!!!

    1. Follow up on the light snow of Sedona...the Gnar was unbelievably grippy on slippery, off-camber, frozen, singletrack. Was slower on moist hardpacked and light mud...but this condition is rare for the a small "con" for roll-resistence. Overall, the Gnar is impressive for my needs! Running the Wren forks with FS Bucksaw aka BiiiG FUN!...again wish the rear spacing could accommodate it��