The hottest topic in the gravel scene right now is tyre width. Here at Curve, fundamentally, we are bike nerds, bike nerds who love riding bikes, so we love to see when a modern trend lines up with our brand ethos and riding style. We have been advocates of wider tyres for a long time now. If you come into the Dream Factory on any given day, you’d have to be very lucky not to hear one of the team discussing tyre options for their next adventure!
The current trend for tires, across the board, is that wider is better, or how April likes to put it, PHat. This can be seen everywhere from road bikes parked up at the local cafe to the biggest gravel races. So the question is, how do you find the perfect tyre setup for your next adventure?
Road vs Gravel (vs MTB?):
This all starts with what kind of riding you are planning. This will hone you in on the style of tyre you need (although we accept the lines are getting very blurry here, what is the difference between a >40mm road tyre and a semi-slick gravel tyre anyway?). The general consensus across all these categories seems to suggest a wider tyre is more comfy and (in the right circumstances) faster rolling. Win-win right?
On the road, we are seeing more and more people running 30mm tyres. Our Belgie Disc will clear a 32mm, and the Ultra even more at 35mm (you can even get a 33mm cyclocross tire in there if you want!) It started with the pros using these magical wider tyres for races like Paris-Roubaix and the Tour of Flanders to smooth out the rough cobbled roads. But now that wide tyres are taking over the Grand Tours too; there must be a reason for it. In the world of Curve, wider tyres make adding in some light gravel duties to your riding possible and more comfortable. We are always advocates for adventure, so being able to add in rail trails or light gravel to your road rides just makes them more fun!
When it comes to gravel, this is where it gets really interesting. The crew here at Curve seem to land in the camp of “fit the widest tyre you can”. With our flagship bike, the GXR4, now comfortably taking 29 x 2.0” MTB tyres, you can get seriously adventurous. April has been test riding her GXR4 with 2.0” Vittoria Terreno Dry’s and has exclusively positive feedback on the improved ride quality.
If you take a look at most bike checks from major gravel races, you’ll see a lot of people using tyres sized 45mm and up - we’ve offered all our GXR4s with 50mm tyres as standard. The added tyre volume and ability to run lower pressure improves puncture resistance and grip, without (potentially) the previously thought trade-off of a slower rolling resistance. What is very interesting, some higher end MTB tires are often slightly lighter than their gravel counterpart, even in wider sizes, for example the Pirelli Scorpion XC RC in a 29 x 2.2” (610g) vs the Cinturato M in a 50mm (705g). If you’re looking at getting more hectic, adding in some chunky gravel or singletrack, Big Kev is designed around a 29 x 2.1”, which puts you firmly in MTB tyre territory.
Obviously, everyone’s set up is individual and different adventures don’t necessarily fit into this camp. For example, the Border Run is designed as a spirited social ride from Melbourne to the NSW border in Echuca and with almost all of the gravel being hardpack and fast, a 40-45mm tyre is likely optimal here. Jesse even rode it this year on 33’s, but we would consider him a hellcat. This is also a breakdown of the tyre width, tread style and picking the best for your course is a blog for another day…
Can I ride on less?:
However, we can’t deny, some of the fun of gravel riding is that you aren’t on a mountain bike. Trails that aren’t that interesting on a MTB with 29 x 2.6” tyres, can be very fun on a gravel bike with 45mm tyres. The art of underbiking can reinvigorate trails and bring them a new lease of life by making them more challenging. It can improve your riding skills immensely, as line choice and having a ‘light’ stance on your bike becomes vital to not shredding your tyres and damaging your rims or other parts of your bike and body.
If you are looking at taking on some single track or even MTB trails on a gravel bike, to avoid mechanicals or even worse: crashes, it is important to factor in your riding style. Riders who are experienced in riding MTB’s are often lighter on the trails and will therefore often get away with riding much gnarlier terrain on the narrower, less resilient gravel tires. If you think you’re likely to be hitting the trails hard, maybe a wider tyre is the one for you!
Insert or not to insert?:
This seems to be something from early tubeless days and the MTB world. Tyre inserts can increase grip and protect the rim from damage when running at really low pressures over technical terrain. They also add the ability to roll on a slow flat, something that at the very pointy end of a race could save your day. However, they do come with a weight penalty, and they aren’t cheap!
If you’re in the situation where you are hitting rough sections of gravel in a group at high speed, inserts could help save you from that unseen rock strike on a narrower tyre. But with the increased shift to wider tyres, there’s nothing to say this won’t do the same thing. Furthermore, if you do have a ride ending mechanical, making your way home with a foam tube wrapped around your shoulder isn't the comfiest thing in the world.
Here at Curve HQ, I don’t know of anyone running inserts, but not to say they don’t have a time and a place.
Tyre Mullet:
Okay I get it, we’re getting really niche here, but I warned you - we are bike nerds. With the GXR4, AIR Kev & Big Kev coming kitted up with our Ride 415 VGM fork as standard, you can comfortably run a 29 x 2.4” tyre (up to 2.6” is even possible with minimal clearance) in the front if you so wish! So if you’re looking for maximum grip through some technical sections on a certain course, you could run a larger MTB tyre in the front and a slicker/faster gravel tyre in the rear.
We fully accept this is definitely in the realm of marginal gains, but if you’re looking for maximum performance, this might be a trick for you.
Suspension on Gravel Bikes:
This might be controversial in itself. But here at Curve, we’re not quite on board with the suspension on gravel bikes trend just yet. Especially as of the time of writing this, the inclusion of suspension on the fork is reducing the available tyre clearance. In this case, we’d lean towards fitting the widest possible tyre and dropping the pressure before thinking about running a suspension fork.
It’s also important to take into account that a suspension fork requires a lot more maintenance. A lower leg service is usually needed every 50 or so hours of riding. Considering how much time many of our staff, ambassadors and regular customers spend on their bikes, hitting the 50-hour mark often takes less than a month (less than a week during a big bikepacking mission). That’s a lot of servicing every year! And this is not even counting the more major damper and air spring services that you have to do approximately every 150-200 hours.
Then you also need to consider the high initial cost of the fork, added weight and, if bikepacking or touring is your thing, lack of cargo mounts.
We’ve also been riding gravel bikes on some pretty rough singletrack for a long time, and we’re yet to find the need for any travel in the fork.
Curve Bike Specs/Clearances:
Belgie Disc: 32mm
Belgie Ultra: 35mm
GXR4: 50mm / 29 x 2.0” (up to 29 x 2.4” front)
Air Kev: 50mm / 29 x 2.0” (up to 29 x 2.4” front)
Big Kev: 29 x 2.1”-2.35” (up to 29 x 2.4” front)
GMX+: 29 x 3.0”
