18 February 2010

bikefix Initial Review: Geax AKA TNT tires

As a general rule, I'm not a big fan of race tires. Not that I have anything against going fast- it's just that so many fast-rolling tires make such significant handling and durability compromises in the name of speed that they don't really suit my more aggressive riding style. Add to that the scarce traction, abrasive rocks and abundant cacti in the Southwest's loose-over-hardpack trails and race courses and trusting $40 in fees and several hours' driving to flyweight race tires never made that much sense.

We first spotted Geax's new AKA at Interbike last fall. The many-knobbed tread is designed to provide traction where the tire is unable to dig into the trail and must find purchase on the surface. The large number of closely-spaced, short knobs suggest low rolling resistance and give way on the shoulders to slightly taller, more aggressive cornering knobs. The AKA comes in eight varieties for 26in wheels (no 29er tires are available at this time): the UST, TNT (Tube/No Tube), and tubed folding and wire-beads are each available in 2.0 and 2.2in widths. The two widths' treads are slightly different, with the 2.2 having a taller, more aggressive version of the 2.0's low-profile tread. Because I feel that a sliding rear tire is easier to control than a sliding front, I decided to split the difference between speed and control and ask our friends at Geax for a TNT tire in each of the two sizes with the idea of mounting the fatter tire on the front of my full suspension bike for this year's 24 Hours in the Old Pueblo.

Charlie and I have written at length about Geax's TNT casing, so I won't spend a lot of time on it here. On the continuum between tubed and proper UST tubeless tires, Geax's TNT casings are a bit closer to the UST side of things. Despite not being a "proper" UST casing, our experience with Geax's TNT tires has been great- they hold air and their shape well and have shown an impressive ability to shrug off assaults from rocks and thorns. Where the tubed, folding 2.0in AKA weighs a claimed 520g and the UST 680g, the TNT version is advertised at 610g- maybe not light enough to change the minds of riders who "convert" tires to tubeless, but anyone who has ended a ride or race on foot due to a cut sidewall should find the additional 90g of insurance worth carrying.

When the AKA arrived, I threw each on the scale (something I usually forget to do). At 625 and 685g, each was 15g over its advertised weigh Other Geax tires I've weighed have come in just under their claimed weight, but the company seems to come closer to the mark than many. I was able to install the tires without needing tire levers or an air compressor on a pair of Shimano XTR wheels, with the recommended two capfulls each of Geax's Pitstop TNT sealant for insurance. With all of the talk of the potential of ammonia to weaken aluminum rims over time, I was surprised by the sealant's sinus-clearing scent. My rims certainly haven't melted, but I thought it might be worth mentioning.

On our local foothills trails (the only trails that have been clear this winter), the combination of a 2.2 (front) and 2.0 (rear) AKA is right up there with the fastest I've ridden. While the tires' straight ahead speed is impressive, it's their ability to carry speed through corners that has really won me over. In twisty, loose singletrack, I found it very difficult to get either tire to break loose or even drift. Granted, a bit of moisture in January means that our trails have been as grippy as we ever see them, but the tires' cornering ability exceeds my nerve by a fair margin. With both tires in their "speed" orientation, I found the rear 2.0 a bit too willing to break loose during standing climbs and so reversed it (to "traction") after a few weeks' riding. I can't say that it felt any slower reversed, but the tire's ability to drive the bike forward improved to match that of many knobbier tires that I've ridden. While not mud tires by any stretch of the imagination, the AKA provide surprisingly decent traction and release mud better than full knobbies once back up to speed. I settled on 30psi for the front tire and close to 35 for the rear- lower pressures made me feel as though the lower-volume tire wasn't protecting the rim from rocks at speed.

The course used for Epic Rides' 24 Hours in the Old Pueblo is very similar to our local trails. The trail surface is generally very hard with a dusting of sand and fine gravel over the top and a few sandy washes here and there. While there are a couple of fast fire road sections, the majority of the race is spent on very twisty, cactus-lined singletrack that can severely penalize riders for overcooking corners. In early laps, fresh and energized, I was really able to explore the AKAs' limits. The tires are impressively tenacious in corners- I only ran into trouble when heavily weighting the front wheel and trying to corner like a downhill racer. It was then and under heavy braking (which also unweights the rear wheel) that the reversed rear tire would break loose. The bike remained controllable, though, and the rear Geax does take a good deal of effort (for a race tire) to provoke into bad behavior.

At some point in the middle of the night, I hit something hard with my rear wheel and felt the rim through the tire. While the Pitstop TNT sealant managed to seal the two holes in the tread, there wasn't enough of the two small capfulls left to seal the bead where each hook was (slightly) bent and I had to fit a tube to finish my lap. Back at camp, a scoop of Effetto Mariposa sealant wasn't enough to get a seal, so it'll be out with the patch kit when I get the chance. I don't know enough to blame the AKA, but can't say that I've ever seen a tubeless tire with twin snakebite punctures. For desert conditions, though, it seems safe to say that the recommended dose of Pitstop should probably be doubled.

Dispite owning a number, the AKA are the first race tires that I am confident riding aggressively. Being able to carry speed through corners rather than having to scrub it off and replace it is fantastic, and the AKA are able to maintain corning traction in some of the trickiest conditions for tires. With only about 300 miles on the combination, I can't speak to their durability other than to say that the double compound (60A durometer Aramid Racing rubber under the tread, 50A durometer Sticky Soft rubber on the shoulders) AKA are wearing better than the Sticky Soft Barro Mountains I wore through this summer. If the 2.0 can't be repaired, I'll likely replace it with a 2.2 for a bit more traction and rim protection. Though the AKA's weights won't excite expert-class racers, the $48 price should, especially if my rear tire punctures were a fluke. Given my previous experiences with Geax's TNT casing and my aversion to walking, the AKA are looking like a very good choice for anyone who likes to go fast not just on the straights but in corners as well. We'll keep you posted...




nkhadakk said...

How did you manage to get your hands on an AKA TNT tire ? I have been back ordered at Cambria Bikes for close to a month(they appear to be the ONLY retailer carrying these tires). I have a non TNT AKA tire on the front, that replaced a Nevegal... and i am amazed at the rolling speed of these tires. (OR i am amazed at the Nevegal's sluggish feel). I use these in colorado loose over hard pack conditions and absolutely have no issues with traction. Knowing better now, I would say nevegals are overkill for most colorado conditions. I am looking for a TNT AKA to replace my blue Groove in the back that is wearing down.

bikefix said...

Mine came straight from Geax- any bike shop with a Bikemine account should be able to get them- though I can't speak to their availability. As an all-around rear tire, I really like the AKA 2.2... marc

Jody said...

The 2.2 apear to have a rather tall casing from the pics, almost mutanoraptor 2.4 tall. I am looking for a new rear tire for my rigid singlespeed and these look like they might be a nice tall, but not to wide tire with good traction vs. rolling for that application. Any thoughts or caliper measurements on that?

bikefix said...


The 2.2 is tall, but I wouldn't say that it's as tall as a Mutano 2.4. It's a good, honest 2.2 for sure, though. I don't have them mounted at the moment, so don't have any measurements that I can share- sorry! marc