The front/rear specific Bontrager 29-3 tires are mounted and have been ridden. Here are my initial thoughts about this newest set of shoes from Bontrager.

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I Mounted the tires to my set of Bontrager Race X Lite wheels using the TLR rim strip. The interface between the tire and the wheel was tight! Much tighter than other Tubeless Ready System tires I have mounted. Since these are pre-production tires, it may not reflect the actual production tires you may get, but if it does, be prepared to work a bit harder to mount these. Not that I am complaining……yet! If ever I flat, I may not like the tighter fit. They hopefully won’t flat, as I used the Caffelatex sealant I am reviewing in the tires.

As I stated, these are pre-production samples, but I was told that they only differ in that the rubber compound used was heavier and a bit thicker on the sidewalls than the production compound. Weight will be less than the tires I have as well, which I found to be within acceptable limits as is. The widths on these tires varies from front to back by quite a bit. In fact, the tires don’t even look like they belong together! The front 29-3 measures 53.4mm/2.10 inch (claimed 2.25 inch) and the rear measures 47.8mm/1.88 inch, (claimed 2.00 inch). Note: These are casing widths, the tread blocks on both tires are narrower.

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The tires when mounted look really miss-matched. The rear is so much narrower and has less volume by far than the 29-3 front. In fact, side by side comparison of the mounted tires shows that the axles of the wheels don’t match up. or anywhere close to it. There is just shy of a half an inch differential in diameters between the two tires. These tires are meant to go together? Well, I figured I may as well give them a shot, even though the differences were so huge. Even the tread patterns are not remotely similar. The back resembling a smallish Python and the front a WTB Prowler. Not that this is a bad thing in and of itself, but along with the other differences, these tires looked like a “Mutt and Jeff” pairing if ever there was one in the tire world.

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So out I went on a fine day in almost perfect conditions. The trails were tacky dirt with plenty of roots and covered in leaves in some spots. I also had a pretty big sandy section in this loop. The trail starts out with a big climb to a switchback and off camber section. Here the tires showed great braking traction and cornering traction. Climbing was good. Actually, I was quite surprised at how well the diminutive rear hooked up. Even standing on steeps didn’t break it loose. I did get a fair bit of skidding and looseness in the rear around a particularly tight downward turning switchback though. Also, I could feel a tad bit of breakaway on the really off camber parts in the rear. The front end stuck like glue though. No wavering what so ever.

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The front tire was impressive in turns and over the rough roots, where the volume of this tire makes up a bit for the lack of suspension on my El Mariachi. I appreciated this very much. Incidentally, I ran 22 psi in the front tire and about 30 psi in the rear. This felt about right from a balance point of view, as I could feel the rim in the rear bottom out once or twice on roots. In the sand the front tire did a fair job of tracking through, but still doesn’t top Bontrager’s folding bead version of the XR. The rear cut down in pretty much on impact with the sand, which is understandable, given its narrow profile. Still, I managed to plow through in an acceptable manner.

A note on the difference in diameter: Obviously, a half an inch in difference here will make a slight geometry change to any rig the 29-3s are mounted to. It will slightly slacken out the head angle and seat tube angle. I did not notice anything while riding my El Mariachi. Perhaps I got used to it immediately, or it isn’t that big of a deal. However; it is worth noting if you get this tire combination for those who think it may make a difference.

The rest of the trail was ridden with no drama. The 29-3 tires corner well, grip on climbs exceptionally well for the size of the rear, and are great rollers. In fact, they roll with little “buzz” at all. Braking traction was great in front, but if you are a heavy rear braking addict, you won’t like the skinny rear.

So, are these tires meant for each other? I would say yes from a performance standpoint. They look odd, but you probably won’t notice that while riding them. Rigid front riders with a bent for racing will like the voluminous front tire and the fast rear. Full suspension riders that race their rigs may also appreciate the combo. That said, there is no reason a rider could not choose to run front 29-3 tires on both ends, or 29-3 rear tires on both ends. In fact, I am told race team members of the Fisher/Subaru squad run the 29-3 rear on both ends at times. To my mind the rear 29-3 looks like the perfect monster cross tire.

I’ll continue to flog these throughout the spring and will report back with a Midterm assessment then.