Bontrager ACX 29"er Tubeless Ready Tires

ACX Tubeless Ready Tires

After running the racy Dry X Tubeless Ready tires up in Decorah, Iowa about two months ago and finding them to be a bit sketchy on their technical trails, I was leery of running them again up there. Especially on the front where I seemed to wash out in switchbacks and off camber corners. Fortunately the good fellows at Bontrager have provided the ACX for just such an instance as this.

The ACX is a stalwart of the Bontrager tire line. An all round trail tire with some bite. Just what I needed for the Tubeless Ready wheelset up front. Those blocky treads were looking good to me for keeping me right side up in those off camber trail situations while still being relatively lightweight.

My digital scale read these out to be 650 grams each. Note, these do not have the slightly beefier “AR” sidewall protection, so those tires with that feature would have weighed in just a bit heavier.

Installation was just like the Dry X tires. They went on with a tight fit to the rim, and aired up easily with a floor pump. I have got to give a shout out to the guys at Bontrager for developing a tubeless tire and rim system that actually fits the tire tight and works as advertised. The airing up process is simple: take the pressure up to about 60psi, and you will hear some loud snaps as the bead sets up. Then let the air back out, take out the removable valve core from the presta valve, put in the Super Juice sealant, replace the valve core, air it up to riding pressure and go for about a 20 minute spin. this evenly distributes the sealant and gets it worked into the casing to aid in air retention. My experience with the Dry X shows that this works and works fantastically well. My tires are holding pressure better than my tubed ones are!

Okay, on to the ACX, which once aired up, seemed to visually look slimmer than the Dry X, but in reality they are exactly the same size once I measured them. Hmm…..sure doesn’t look like it, but it is! Out on the trail, the ACX that I mounted up front took care of traction business like a Velcro strip! That blocky tread just has gobs of traction. I was running these on tacky to dry trails most of the time which didn’t faze the ACX at all. I ran it hard into corners, and off camber was a simple matter of letting that front tire do it’s job while I looked for the best line through. No worries about traction any more.

I paired the ACX up front with the Dry X in the rear. I did this because the ACX has more rolling resistence and the Dry X seemed to be getting the job done in the rear. This combination worked great for an all around trail set up. During commutes, that ACX rolling resistence could definitely be felt, but I’ll take that confidence inspiring traction as a trade off for mountain biking any day.

If there is one thing wrong here it’s the width of the ACX. I wish it were a 2.3″ , or even a 2.5″ tire with a high volume casing. While it would certainly weigh more the added traction, and cush would be a welcomed thing, especially for rigid fork and all mountain riders. A Tubeless Ready 2.3 inch ACX? I think it’s a no brainer.

As it is, the ACX is a high traction, all around trail tire that is a great addition to the Tubeless Ready arsenal. And I’ll give you another tip: It plays quite well with the Mavic Crossmax 29″er wheels tubeless too! ACX Tubeless Ready tires should become available any day now and will be $39.99 MSRP

I’ll be riding these Dry X and ACX tires for the rest of the summer. I’ll be checking in with updates every so often, so stay tuned!

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No Responses to “Bontrager ACX 29"er Tubeless Ready Tires”

  1. The Monkey Says:

    I’ve been running these tires for anbout 2 months now. With a Stan’s Arch rim, airing the tire up was pretty simple. With one side open on the rim, I added 2 scoops of sealant to the tire before pulling the other side of the tire over the sidewall. I have a spray bottle of soapy water that I then squirted around the sidewalls of the tire so any escaping air would make bubbles. Then I put it on the compressor.
    Snap! Snap! Snap!
    They sealed right up, no leaks. At 40 psi I took it for a ride in the parking lot.
    I generally ride them at about 25-28 psi, grip is everything G-Ted says.
    These are by far the easiest tires to mount tubelessly on Stan’s rims. Traction is great, but a 2.3 would be a little slice of heaven.
    And they are available now!

  2. Toddre Says:

    Can you clear up for me… can these tires be “stan-ed” or are they only compatible with the tubless rims by Bonti (and Mavic)
    I LOVE ACX tires as a front and want to convert to tubless but I don’t have the $$ for wheels…will it work with a Race wheelset?
    Thanks

  3. Guitar Ted Says:

    Toddre: Stan’s should be okay, but you won’t get an “official” okay on that.
    Take a look at The Monkey’s comment, he knows what he’s doing, you can take his word for it. 🙂

    I don’t think the Race wheel set has a plastic rim strip available that fits it. However; you can get the TLR rims from Bontrager and then build up your own set, or go with one of the Stan’s newer models like the Arch or Flow which are getting rave reviews. (By the way, if you go the Bontrager route, don’t forget to order the rim strips too.)

    Finally, the Rhythm wheels will be coming out soon and I believe that the lower end one will be quite reasonably priced. 28mm wide rim, Tubeless Ready with the supplied rim strip, and convertible from QR front to 20mm thru-axle. I rode a Rhythm wheelset at the Big Wheeled Ballyhoo and they felt really solid.

  4. Tom Says:

    Can you buy Bontrager “tubeless ready” rims in 32 hole drilling? All I can find online is about their wheelsets.

  5. WillitsBikes Says:

    I’ve been riding these tires on my DT 240s/Bontrager TLR wheelset (with Stans fluid to boot) for 2 weeks. They’ve been great for me in the damp overgrown post monsoon Austin trails. Lots of confidence in the corners with the way they popped into the rimstrip. I must say I did cut the tire in the first 5 minutes of riding them and the fluid ultimately failed, but along with Stans fluid (or not cutting my tire) this setup should be killer. Lighter than my I9s but not as stiff and I miss those 6 pawls. I do like centerlock rotors though. Anyway…

    -steven

  6. WillitsBikes Says:

    Tom, 28-hole only.

  7. Mike Says:

    I wonder if the rims are available separately so I can relace my Bontrager Race X lite 29er wheels with the tubeless rims? These wheels are very expensive ($800 list price for a pair).

  8. Guitar Ted Says:

    Mike: You might be interested in the Rhythm wheel sets instead. I’ll be posting on those very soon, so keep an eye out for that. Bottom line is that they are much more affordable and probably a better choice for most trail riders.

  9. Jeff Says:

    I’ve ran these tubeless on x-lite wheels with Stans and have been disappointed. Although they mount up well and hold a line, they flat very easily, especially in the rocks here in southern MO and this last weekend at Chequamegon. I’ve had tread flats and a sidewall cut. The tread flats I’ve fixed with locktight 380 and Hutchinsins tubeless repair kit. I haven’t tried to fix the sidewall cut; that almost new tire is shot.

    In each case the sealant also failed. One of the tread flats was on a gravel road training ride! Thorns do seem to seal, however.

    The sidewalls and tread are very thin which I guess is what you expect on a light 650 gram 29 inch tire. I’d like to see a tough 900 gram or so 120 thread count tire like the 26″ 750gram tubeless ACX which I’ve had good luck with.

    Maybe somebody from Bontrager will read this. It’s cost me in my last two races and I’m sure I’m not alone.

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