Size matters — but so does the casing: a Schwalbe G-One RX Pro gravel tyre review

Gravel tyre width is a moving target at the moment. At some point, we can expect sizes to stabilise but we have yet to reach that inflection point. Right now, many gravel bikes do not have clearance for tyres larger than 45 mm, but for bikes with the space, there are several newly released tyre options in the 50+ mm range.

The reason for wider tyres is simple: more volume allows for lower pressures, which combined with thin, flexible sidewalls bring increased traction and comfort as well as decreased rolling resistance. Because pressures are low, the sidewalls are less prone to cuts and punctures (if you’re skeptical about this, imagine a full balloon vs. a partially deflated one: the full one will pop if you look at it the wrong way while the deflated one will thwart even a pair of scissors).

The Schwalbe G-One RX Pro tyre slots into Schwalbe’s new gravel Pro series as the most aggressively treaded of the three. It is designed to maximize grip in rough terrain and muddy conditions while still rolling well and clearing debris efficiently. It is available in three sizes: 40, 45 and 50 mm (as tested here).

Design and construction

The G-One RX Pro uses the same carcass construction and compounds as Schwalbe’s MTB tyres. What has changed is the size (they’re smaller) and the tread patterns, which were designed specifically for gravel riding. The RX Pro features dual compound tread (harder in the center, softer on the shoulders) developed in conjunction with Schwalbe-sponsored professional athletes.

The RX Pro has a chevron center tread with interlocking intermediate knobs that abut longer, alternating side lugs. All of the knobs are spaced out to aid with mud clearance, but together they form a cohesive shape that keeps tread on the ground regardless of the angle of the tyre.

The carcass design has been updated from previous gravel models with a wider protective layer under the tread. There are two sidewall colour choices (Black and Transparent) on offer.

Previously, Schwalbe only offered gravel tyres up to 45mm but that’s no longer the case with the introduction of this new line. When I asked my Schwalbe contact about tyre width, they said: “With the growth of the gravel market and the trend growing wider, we’ve started to offer all Pro line tyres in sizes 35mm-50mm widths in 5mm increments. As frame clearances evolve we will most likely see tyres going even wider in volume.”

I’m predicting a wave of 55mm tyres in 2027; mark your calendar.

Specs

• Name: Schwalbe G-One RX Pro
• Price: $88 USD
• Available Sizes: 40, 45, 50 mm (model tested)
• Weight: 619 grams
• Colours: Black, Transparent (Tan)
• Hookless compatible: Yes

The ride

After unboxing, the first step I take when testing tyres is to weigh them. Schwalbe lists the G-One RX weight at 615 grams. My test tyres came in slightly heavier than that, but not by much.

Installation was smooth: The trickiest bit was at the beginning—fighting the first bead onto the rim took some effort, but once that was complete the second bead popped over easily by hand, and my little air compressor had no trouble getting the tyres to seat fully. It’s rare to find tyres that install this easily. On 25 mm internal rims, the RX Pro tyres measure 49.5 mm.

Once I installed sealant and inflated the tyres up to about 40 PSI to sit overnight, I then dropped the pressure using my highly calibrated “squeeze test.” Silca’s tyre pressure calculator corroborated my approach almost exactly, spitting out an answer of 22/23 PSI based on my inputs (weight, tyre size, and expected terrain). I have found Silca’s calculator to run a bit high in the past, but this seemed pretty spot on. On a rootless route, I could probably go lower.

My first ride on the tyres took me through Seattle’s quieter neighborhoods to a park in the city that contains a mix of loose gravel and some singletrack. The ground was damp but not soaked. On mostly chip-sealed and concrete-paneled roads on the way there, I felt like I was floating. Sometimes, it takes a while to find this pressure sweetspot, but I got there from the first pedal strokes. Off road, I was very impressed with how they performed on both singletrack and gravel paths, providing the confidence I’m accustomed to on a mountain bike.

On subsequent testing days, I had trouble getting these tyres to lose traction even in loose sandy soil. The tread pattern and thin casing really do a good job connecting with the ground. I also felt comfortable leaning the bike over on pavement, without experiencing any squirminess sometimes present with knobby tyres on tarmac.

Whether or not the dual compound helps with rolling resistance remains an open question. I’m not sure that the harder rubber actually makes the tyres any faster on pavement. It should wear better (ergo, last longer) but it probably makes the tyres slower everywhere except on a steel drum test. Schwalbe uses a smooth drum roller for its testing, so it’s not surprising that this is the direction the company went with the design. I have some doubts about this testing method, as I think it is not reflective of real-world riding conditions.

I was curious to know whether or not Schwalbe tested these new gravel tyres against its quite fast-rolling Thunder Burt XC model. Here’s what I heard back when I asked: “We do not have any direct comparisons between the Thunder Burt and G-One RX Pro to share. We utilize specific testing protocols for our categories based on their use case. So, the Thunder Burt and G-One RX are tested at different air pressures and speed, making the numbers we have inaccurate for direct comparison.”

In addition to spending some time on the RX model, I also had the opportunity to test out the new RS tyres, a semi-slick intended for smoother roads. It has a directional tread, depending on which wheel you install it on, to prioritize either grip or rolling speed. I got on similarly well on these tyres and think that one of the most intriguing benefits about this suite of tyres is the ability to mix and match tread patterns between the three. With identical sizes and casings, it’s very easy to swap in a grippy front and slick rear, or any other variation one wishes to try, and have them perform well in concert.

Value and conclusion

Not everyone needs or wants 50mm (2.00 inch) tyres, but if you have a bike with sufficient clearance, I highly recommend trying them out. The more we collectively understand about the science underpinning rolling resistance, the more that wide tyres seem like a no-brainer. The key, however, is in the casing. It’s easy to focus on width, but width only matters if the casing is supple enough to soak up variations in the ground. This takes time and experimentation on different terrain and at different pressures to understand. And there are downsides to wider tyres: more weight and additional aerodynamic drag. Compared to the increase in rolling speed and comfort, however, I'm inclined to focus on the positives.

Schwalbe has done an excellent job with this tyre and, more broadly, this series. Using these three tread patterns in combination, and mixing and matching as needed, should allow riders to optimize traction for any gravel ride or race they might undertake. It’s really all I can ask for from a tyre. And while they are expensive, good tyres are always worth it.