Mixing road & gravel – 1 set-up for everything

Posted by Gerard Vroomen - 17 March 2020

[updated April 2022]

In a previous post (now updated) we looked at gears and tires if you have 2 wheelset: 1 gravel, 1 road. That’s a great set-up if your road and gravel rides are clearly separated. But many people go on mixed rides, with sections of road and gravel/dirt on the same ride.

You might do that because it’s fun or because the gravel/dirt sections where you live don’t connect into a large enough loop. Whatever the reason, you’ll need to find a tire that works well on all these surfaces, presuming you don’t have a team car behind you with a spare set of wheels!

Option 1: It’s mostly gravel

Think about how much asphalt you need to link together your gravel sections. Obviously, if your rides contain 90% off-road, you don’t really want to make any changes for the 10% on-road of your route. You pick the tire that suits the gravel/dirt where you live and you’re done. This can be anything from a beefed up road tire if the gravel is very smooth up to a 2.1″ mountain bike tire if you ride very rough stuff.

Option 2: The road is long and the gravel easy

If it’s the other way round and your gravel/dirt sections are few and far apart, it’s a little more complicated. For option 2 we assume there isn’t that much gravel and the sections that you encounter are easy. In this case, you pick a road tire with just enough tread and toughness to avoid walking and punctures on the gravel or dirt. Go for tubeless if you can.

This is the type of riding you can do on skinny road tires, but if you have a gravel bike, why would you? Since you have the tire clearance, you may as well go with a bigger road tire for extra comfort, grip and puncture protection.

The Pirelli Cinturato road tire (there is also a gravel tire by the same name) is a great option, as it is a high-quality, smooth-rolling road tire that comes in a 35mm tubeless version. The WTB Expanse & Exposure are also great options in various widths, with or without some small side knobs.

Continental has the GP-5000 Tubeless in a 32mm width, which on most rims will be wider than that (for example on our Discus 45 | 32 carbon wheels, it measures 34.2mm wide. Schwalbe has the Pro One TLE and One TLE in 30mm wide, or even the E-One which is designed for e-bikes and offers some extra protection. Note that the WAM (width as measured) on these Schwalbe tires is a little low, so combine it with a wide rim to get the volume you need.

If you like small companies that make great product, take a look at the René Herse Bon Jon Pass TC which is 35mm wide (or its siblings in widths from 26-55mm!) Note with René Herse that every width has a different name but they are often similar in style.

Panaracer has the GravelKing, which despite the name has a profile perfect for rough roads. It comes in widths from 32-48mm, standard and tubeless.

What all these tires have in common is that the extra width (and therefore air volume) gives you cushioning to avoid flats and allow you to ride at a lower pressure for better grip. As an added benefit, they also make your paved sections more comfortable. Not a bad thing since a lot of places we ride have asphalt with cracks and potholes that make gravel roads look like advanced technology.

Options 3: When the going gets tougher

If the gravel or dirt sections are very technical, then you will need a certain “level” of tire and range of gears to conquer them and avoid walking. Because no matter how speedy your chosen tire is on asphalt, if it causes you to walk, you’ll be slower overall. Even more importantly, you’ll be grumpy, tired and sore.

Even if your ride is 90% on-road, if the off-road sections requires a knobby 2.1″ tire, you have no choice but to go with it.

However, your tire choice still matters. Among the chunkier tires, there are some that roll much better than others. Key factors here are the knobs in the center (can you get away with smaller knobs there?) and the casing design (this is harder to assess for consumers).

Schwalbe has some large 650b casings that rank among their best regarding rolling resistance, even compared to their 700c road tires. The Racing Ralph, Rock Razor, G-One Allround and G-One Bite are examples of this. We know from our tests that some of these do not perform that well in the windtunnel but you can’t have it all.

Other 650b options are Vittoria’s Barzo, Pirelli’s Cinturato Gravel M, Panaracer’s GravelKing SK and several René Herse tires.

There are also 700c options with chunkier treads. Not as grippy as the more extreme 650b offerings, but a WTB Nano 40c, Pirelli Cinturato M or Panaracer GravelKing SK might just be tough enough for this purpose.

Option 4a: Truly mixed terrain – dry-ish

However, most people find themselves in a different situation. Where most people live, you will need significant portions of asphalt to complete your rides while mixing in as much gravel and dirt as you can. The ratio could be 40/60 or 60/40, that doesn’t really matter. Also the wheel diameter isn’t that critical, you could go for 650b or 700c here.

If the gravel and dirt sections are really tough, that’s not really Option 4. Then Option 3 above applies. For Option 4, picking one tire that gives you enough grip on gravel and rolls nicely on pavement is the key.

If you live in a drier area where grip comes from surface area and even a slick road tire will work off-road (and of course be great on-road. Then you can pick any of the road tires from Option 2, trending towards the wider René Herse, Panaracer and WTB options as your off-road sections gets tougher. To add additional puncture resistance, dive into the various protection layers these companies offer.

The Pirelli Cinturato H is another option with a small profile for hard surfaces. The Schwalbe G-One Speed is also worthy of consideration.

Option 4b: Truly mixed terrain – wet

Again, if the gravel/dirt sections are very tough, that’s Option 3, not this option. Option 4b requires more profile because of the wetness, so surface area alone is not enough for grip. That said, surface area does help, so 650b could be a good choice over 700c in this case. They will be wider, thus allow for lower pressure and hence have a bigger contact patch (which in turn means more grip or a chance for a smaller tread profile).

Schwalbe offers the G-One series for this. They come with small, medium and aggressive knobs indicated by the suffix Speed, Allround and Bite in their names. Widths range from 35-60mm.

The only one I would not recommend is the G-One Speed in 27.5×2.35″. That tire is very hard to set up correctly; either the pressure is too low and it rolls poorly on-road or it’s too high and it doesn’t grip off-road. I am sure there is a perfect pressure somewhere so that it all works well, but I haven’t found it yet.

Other options are Panaracer with the GravelKing SK (several widths) or Pirelli with the Cinturato Gravel in several widths and two profiles: the aforementioned H with a small profile and the M with a deeper profile for mixed terrain). WTB offers the excellent Riddler & Nano while René Herse has the Steilacoom TC in 38mm.

Note: 650b vs 700c

You may note that in the above, I don’t talk much about 650b vs 700c. That’s because it’s largely irrelevant for the ride. It doesn’t matter what the rim diameter is, it matters what the tire diameter is (that’s what you roll on). Tire diameter hardly differs between 650b and 700c because the 650b tires are not only wider but also taller, making up for the smaller rim diameter to create a similar tire diameter. In addition, tire width has a much bigger effect on rolling resistance, drag and air volume.

Sometimes people tell me they want 700c “because I am used to that from my road bike”. But what are they really used to? Are they used to a rim that is 622mm in diameter (because that’s what 700c means) or are you used to a road tire that is around 685mm in diameter (the outside diameter of an average road tire)?

Of course it’s the latter, all your ride feel and all steering dynamics come from the tire diameter, not the rim diameter. Nobody can feel what the rim does, you feel what the tire does. So if 685mm is what you are used to, it will feel much more similar to ride a 650b x 47mm tires that is also 685mm than to ride a 700c x 47mm tire that is 715mm in diameter. (not to mention the toe overlap, head tube rise, etc).

But my real point is that neither really matters. You pick the tire width based on the terrain you ride on and your speed/skill level and then you figure out if that best fits on your bike in 700c or 650b (based on tire clearance and resulting bike geometry).