In 2018 at Dirty Kanza, we saw none other than Sven Nys unveil prototype Bontrager gravel tires after starting on Challenge Gravel Grinders and suffering multiple flat tires.
That prototype tire, the Bontrager GR1 TLR Team Issue, is now available, and we’re rolling on a set. Today, we take a first look at both the 35mm and 40mm versions. Could the GR1 be the right choice for your next gravel adventure or perfect tire for your next dry conditions cyclocross race?
The GR1 is a blunt point file tread tire, with three different knob shapes. There’s a row of arrow-shaped center knobs, three rows of six-sided parallelogram-type knobs on each side, and a slightly larger, better-supported side knob of similar shape.
The small, tightly spaced, squared-off knobs offer a similar knob height and size as the excellent Panaracer Gravel King SK, with a bit more of a directional suggestion and tighter density. Compared to the pointed knobs of the lightweight Challenge Gravel Grinder TLR, the Bontrager GR1 should be longer-wearing, and similar to a Gravel King SK. Knob heights measure just over 1mm tall.
The tire comes in two widths, and two colors. There’s a 40mm wide version, and a 35mm version. Trek’s website lists the 40mm as available in black and brown sidewalls, while the 35mm version is only available in black. Lucky us, we also landed a version of 35mm in brown sidewall, so you know it’s coming. Currently it’s just in a 700c diameter. No 650b/27.5″ version yet.
Bontrager GR1 TLR Team Issue Gravel Tire Specs
First, as we’ve long maintained, you can’t trust labeled widths from any brand, so we’ve measured the tires bead-to-bead (read why here). The 40mm version is 103mm bead-to-bead, which matches the versatile Teravail Rutland 700x42mm gravel tire, but is a whopping 10mm smaller than the 42mm Challenge Gravel Grinder TLR. The 35mm version measures out at 89mm bead-to-bead, which is 5mm narrower than a 38mm Gravel Grinder (3mm in bead-to-bead equates to about 1mm inflated).
The 120 tpi tires are relatively light. Our pair of 40mm tires averaged 444 grams (nearly identical to the Rutland 700×42), while the 35mm version averaged 381 grams.
Inflated at 30 psi, the 40mm tire on a 19.2mm internal width rim measured out at just over 39mm wide. By our calculations, on a 22mm rim, you’d be right at 40mm wide.
Bontrager GR1 TLR Team Issue Gravel Tire Installation
If your fingers and ears are guides, the GR1 Team Issue tires aren’t the tightest fitting tires in the world. Any rim with a decent channel will make for tool-free installation. With a compressor pump on a Vision Team 30 tubeless disc rim, it only took one try to inflate the tire, but it didn’t happen with the satisfying audible snap typical of tight-fitting tubeless tires.
Perhaps in part due to the looser bead, our first inflation didn’t hold long, but with a bit of shaking and spinning, a second inflation up to 60 psi did the trick.
Bontrager GR1 TLR Team Issue Gravel Tire First Impressions
The tight, small knobs of the GR1 create a fast-rolling tire with consistent grip on hardpack dirt and fine gravel. Unlike some tires with a smooth center ridge, the GR1 isn’t so bipolar in terms of traction. You don’t need low pressure or to lean the tire over to get more bite, as it’s consistent through all angles.
The tire is relatively supple. It’s not as supple as the high-volume, lightweight Challenge Gravel Grinder or lightweight but undersized Maxxis Rambler EXO 40mm tire, but initial rides indicate it’s on par with a GravelKing.
If you’re used to bigger side knobs, cornering on really loose surfaces or on anything damp will require more attention. Of course, as a gravel tire, it’s not really designed for mud, and most typical gravel tires slip in really loose, steep conditions. For more rugged conditions, Bontrager also has its GR2 Team Issue tire, with bigger, more spread-out knobs. (In loose, dry conditions, we’re often counter-intuitively reaching for mud tires or gravel tires with more aggressive tread.)
While our initial rides haven’t been in areas filled with sharp, sidewall-cutting rocks, so far we’ve enjoyed flat-free and burp-free riding, but the tires have been needing a daily top-off of air, perhaps due to the loose bead. We’re optimistic they’ll seal up more over time.
Only a long-term test will reveal long-term durability. However, once the bead seated and sealed the casing did not bubble or leak sealant, suggesting a well-sealed sidewall with plenty of butyl protection.
Stay tuned for a report on durability.
Bontrager GR1 TLR Team Issue Gravel Tire Specs
Tire Tested: 700c x 40mm, 700 x 35mm
Casing: 120 tpi, black or brown
Price: $64.99 (40mm), $54.99 (35mm)
Weight: 444g (actual, 40mm), 381g (actual, 35mm)
Width: 103mm bead-to-bead (700c x 40mm), 89mm bead to bead (700c x 35mm)
More Info: bontrager.com