It probably also depends on what you mean by gravel…
This. Which is also this:
Based on the BikeRadar typology, or perhaps taxonomy, I’m on and seek out Type 3 and Type 4, which is probably why I find 47mm tires the most adaptable and flexible. (I don’t think their typology adequately categorizes my terrain, FWIW.) The 47s offer comfort, grip, and confidence in the different conditions, including weather, where I ride.
I had the opportunity to test ride a bike with 32mm tires on my local trails, and the grip was not the same. That makes sense, of course. There were trails I’m not sure I’d want to take that bike on, whether rocky single track or the 20-25% gravel & dirt inclines I regularly ride.
I do see more and more skinny tire gravel / CX bikes on sections that are close to BikeRadar’s Type 2. However, I haven’t seen those bikes on more technical sections (rocky, rooty, loose grip up or down, etc.), nor have I seen their skinny tire marks. Well, very, very rarely have I seen their marks. Me-thinks that’s because riding the skinny tire on those sections may require higher skill than I need (or have 
) with my relatively fat tires.
Get the bike with the ability to take a 45-47 tire, and then find what works for you. Of course, also consider the rims, unless you’re keen on having two wheelsets & cassettes.
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I haven’t seen the Diverge mentioned much here. Can take 700c x 47mm and 650b x 2.1" according to specs. I like the “Locker” storage concept. Can go with/without the STR suspension (without for me). Plenty of mounting points for racks, bags, fenders if that’s your thing.
I personally already have an FS XC Bike and a Road Bike, been thinking that the Diverge or the Grizl might fill the middle ground well for everything from Gravel Events, Commuting, Touring / Bikepacking type events.
Comments?
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Oreo, have you ever ridden a gravel bike with 38mm tires in the sand? Honestly it sounds like you just made that up. Cutting through the sand is never faster than riding across the top. Riding sand is certainly a skill for CX racers and they have no choice but to cut through.
As said above, CX races use skinny tires per the rules not because it’s faster. They’d probably use mountain bikes for gnarly courses if they were allowed to use the fastest bike possible.
Belgium beach bike. Of course they ride on wet hard packed sand. Beach bikes designed for dry sand have balloon tires.
All I’m saying to all the nay sayers is those guys with Cutthroats were faster than me in many conditions (faster to the point of leaving me in the dust) and they kept up just fine on all the other sections of “gravel” where my bike would have been at a theoretical advantage.
Yes, it comes down to your local conditions. And a 40-45mm tire may be ‘just fine’, ‘plenty’, or ‘good enough’ but it may not be the fastest.
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How long was your ride that day? And, what would have been the result if it was an event like Unbound? And, are you sure they’re not just in better shape?
I guess point being, of course there are scenarios where large tires have a benefit. That’s the reason there are fat bikes. But there are also scenarios where they’re a detriment. More mass, more drag, and more (not less) rolling resistance in many cases.
Basically - everything is always a tradeoff. A jack of all trades will always be a master of none…
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I live in Appalachia and our gravel is bit more tech than other areas. I ride 45s most of the time on my Diverge, and never ride below 40s. I also own a Cutthroat with 2.1 Mezcals on it, I don’t think the Cutty is any slower until you get on paved surfaces or on flat terrain.
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This was 50 rides over a year. I have no idea what the gravel is like at Unbound which brings us back to it depends on conditions. All I’m saying that fatter tires are often a lot faster when the going gets rough and they aren’t noticeably slower in normal conditions.
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But they can be noticeably slower as time on the bike and pace goes up for evenly matched setups. Depends on the conditions, pace, pace over time. It goes both ways.
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As others have touched on, the answer to any tire question is a combination of the terrain you’re riding on, the conditions (how dry/wet it is that day/on average) and your preferences.
Start with this article from Cycling Tips that describes various gravel types.
Then talk to people that ride the places you want to ride and ask them which best describes the terrain.
Then think for yourself what is important to you: ultimate traction for confidence, lowest rolling resistance, super puncture resistance, etc.
Then ask people familiar with that terrain what tires best match your properties and the terrain. Get several opinions on that and make sure the bike you get is capable of running the most common responses.
Personally, I have both 700x45 and 650x50 tires with the same tread pattern. I hardly touch the 700x45 because running the 650x50 is more comfortable and encourages me to explore pretty much any trail (even light XC MTB) that I come across on my rides. But if I could only run 700x45 I wouldn’t even know what I’m missing, they are enough for sure in SE MI.
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It’s a little known fact that fat bikes were first used for sand riding, but obviously they quickly were adopted for snow riding.
Not to head too OT, but are you sure about that?
My earliest memories of the origin of modern fat tire bikes comes from Iditabike (est. 1987) with the OG’s using double-wide rims and tires stacked for a super wide wheel/tire setup.
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See here. The guys in Alaska were riffing on what was already done for the sand.
Edit: I guess it really depends on where you draw the line to say which bike first qualified as a fat bike to say who invented it. Regardless, sand was very much a motivating factor for going very wide with tires
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Very interesting, thanks for the info & link.
No, but I have ridden my road bike with its 28–30 mm slicks and lots of mountain bikes on sand.
The conclusion is simple: there are many types of sand, and a tire that works well in one situation will work miserably in another. I sometimes ride my road bike on beach parking lots which are compacted earth with a layer of sand on top. That rides completely differently than sand on top of moist soil in Bavarian forests or the thin layer of sand dust on top of rocks that the Chileans lovingly call “anti-grip”. Has the sand been compacted or is it loose? Is it wet or dry? I don’t think I have ever ridden on a beach itself (the combination of salt water and sand is a killer), though.
There are definitely situations where a thinner tire works better just like there are situations where a wider tire works better. E. g. if you have a relatively thin layer of sand on top of a surface with good grip, perhaps a narrower tire might work better. However, if the layer of sand is so thick that there is no chance to reach a better “surface” for your tires to grip on, a wider tire might be better (ignoring, of course, that this might mean a tradeoff for the long stretches without sand).
It might be that where you ride, wider tires might be the best answer to get over those sandy bits. Coming back to the topic at hand: I don’t think wheel diameter matters if you are interested in wider tires. (Many gravel/all-road bikes allow for wider 650b tires than 700c tires.) How long are these stretches of sand, and is it worth optimizing for them? I don’t know the answer to that, only you do.
But one appeal of gravel riding as I understand it is that there are situations where you are underbiked/under“tired”, and that any choice involves tradeoffs. Different routes/places might mean you want to choose a different tire. As far as I understand, that’s part of the fun of gravel riding. Again, I am not arguing against your assessment that you found wider tires work better for where you ride.
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I always thought it was the other way around, fat bikes were invented to allow people to ride in the snow. I know there were beach cruisers around when I was a kid, but those were vastly different from mountain bikes — and just looking at them, fat bikes have as far as I can tell been derived from mountain bikes, not beach cruisers.
My impression was that mountain bikers first welded two mountain bike rims together to allow them to ride their trails and routes in the winter. I could be wrong, though, I’m not a cycling historian.
Fascinating. Thanks for posting.
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They also scout the whole course before racing, which isn’t how I usually approach my gravel rides
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Yes. Unless you want to do MTB trails in your gravel bike, which is a personal choice I respect.
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What about Midwestern mtb trails on my CX bike? I mean, I really developed strong grip-strength on single track with cantis, and with a 39 inner ring, I worked on my torque.
Not ideal for performance, but fun for development.
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I went down this road of building up bikes that fit larger and larger tires. I am in No VA and our gravel around here is very tame, though I enjoy taking my bike on less-technical MTB trails too.
I had 29x2.2" (56mm) at one point, but have been slowly backing that down to more normal sizes. Now I have 700x45mm tires which are definitely plenty large and are a much nimbler & faster-rolling setup.
A few comments:
- Big-volume (>45mm) 700c/29" tires on a gravel bike are really more for bike packing comfort, IMO.
- A smaller-diameter high-volume tire is definitely a more playful setup. I am actually going to setup some 650B/27.5 wheels with 2.25" or 2.35" for when I want to take my gravel bike on singletrack.
- But a mountain bike is definitely the most fun way to ride singletrack.
- While it’s true that bigger tires don’t have to be slower, in practice they will be. Unless they’re Rene Herse tires (or similar), they’ll be MTB tires. And if they’re RH tires, then they’re just adding comfort not off-road capability.
- Finally, I will say that running extra light Rene Herse 44mm tires, or currently, Challenge Strada Bianca 40mm are really great for general purpose riding or light gravel.
My primary bike maxes out at 45mm tires and that is plenty IMO.
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