I rode with a bunch of guys riding CX bikes while I was on my fancy gravel bike. When we hit the rocky sandy course, they were wishing their frames were a little wider to fit bigger tires. I’m a convert, put the biggest tires you can fit.
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I tried everything from 25mm road tires to 38mm gravels. My frame wont take wider tyres.
I am now on 35mm Panaracer GravelKing. Great! Just love them, tried on dry, wet, muddy, even snowy surfaces, hilly or flat, rocky or sandy. Good compromise and happy to have them! Actually they even roll quite ok on asphalt too.
Even on the slightest of soft-road, a 38 will destroy a 33. I recall shaving a full minute of a 7min long Strava segment on a pretty smooth, hard path on 42c over a 35c. Going from 60psi to 35psi on even the smoothest of dry ‘soft road’ made a huge speed difference.
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If you support a 33, I would like to see that data to support that view point.
Gravel varies greatly from area to area. I’ve ridden “gravel” roads in Colorado on my road bike with 25s no problem. For those anything over 35 is overkill. But those gravel roads are smoother than many paved roads here in TX. Most of the gravel roads I ride are topped with crushed limestone which starts out with very large chunks that are loose and over time is ground down by traffic. For these roads I want at Least a 38 and I typically run 40s. I would go larger but there is always some pavement mixed in and I find a fast rolling 40 to be a nice compromise.
https://marginalgainspodcast.cc/asymmetry-part-1/
Dont know if anyone has listened to his stuff, but there are a few pod casts that speak to tire size.
This is something I’m very passionate about. I personally feel that the “bigger is better” push is mostly nonsense. Unless the terrain you’re riding explicitly requires a wide tire (what I consider to be >35), 32/33s are the best of all worlds. To me, wide tire terrain would be larger rocks and/or mud. The amount of rotational weight that comes from these big tires outweighs all the benefits of comfort/suspension in my opinion, especially since gravel rides are typically longer.
I have yet to ride a route where I felt that a tire greater than 32 would have benefitted me. If you’re looking to slog away the day and enjoy the comfort benefits associated from low pressure/wide tire, then go for that. If you’re wanting to be efficient and carry any sort of speed for an extended period of time, I prefer to go “narrow”.
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The only data I have is the feeling in my legs trying to turn over a heavy 40 tire for 6 hours. Never again.
What kind of dirt/gravel terrain do you typically ride? The trails near me are not fun on anything below 35ish. Plenty of chunk, deep sand, double track, etc. I wish I had some smoother roads that aren’t washboarded so I could run narrow tires.
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@ciarri, not only what/where do you ride? but what’s the Kg on top of the saddle? @gottajibboo, I can’t imagine I’d feel the mass difference between a 40 and a 38, or a 38 and a 36… Sure, a difference arises somewhere, but how tangible is it based on 2 or 4 mm… vs the comfort difference I can feel based on 5-9 PSI on some chunky gravel?
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What kind of data are you looking for? Tire choice is one of the most subjective and personal things out there.
I spent the most of the last three seasons of gravel on 33mm tires - depending on the time of year I’d either be on Challenge Strada Biancas or Challenge Chicanes. Two years with tubes, last year tubeless. Tire pressure generally in the range of 24-30 psi (at 55kg rider weight). I also tested the same tires (not quite the same, the Strada Bianca comes in multiple widths but the Chicane does not so I ran Gravel Grinders in their place) in 36mm and 40mm widths. For me, typical riding is pavement, hardpack, deep but still relatively fine (under 30mm) gravel, and singletrack. I prefer the handling manners of the 33s overall, but especially in wet or snowy conditions. The wider tires were definitely a bit faster in sand, at the expense of some control. I don’t like the way the wider tires feel as the casing deforms, I think that at those widths you’re probably better off with a higher pressure and knobbier tread for grip, and using the extra tire for comfort. Personally, coming from a cyclocross background, that’s not my riding style and I would rather have the least amount of tread I can get away with and run as much rubber in contact with the ground as possible. 33mm tires behave in a way I’m very familiar with, very comfortable with, and don’t have to think about so that’s what is fastest for me.
Again it’s all personal preference. If you’re new to gravel, I’d go with a wider tire if you have the option. GravelKing SKs are well-rounded, and very good tires to start off with. If you want a bit more speed on pavement and very hardpack dirt, maybe look at something with a slick center tread like a WTB Byway or a Vittoria Terreno Zero.
Have fun turning over 33s for six hours then. ¯_(ツ)_/¯
Anyway, to get back to @blind76 - Find something you’re comfortable with and run it. If you aren’t comfortable with anything yet, pick an intermediate tread, buy a pressure gauge, and really learn that tire. Get comfortable with it. Then try another. Learn it. Make comparisons, then make choices. In gravel your tires are all you have for control and suspension, and being comfortable with that is just so important.
TL;DR It doesn’t matter what tires you run as long as you’re comfortable with them.
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When people have tested tires with data they always state run the widest tire with the lowest pressure.
Did you do the Chung method to determine which was faster or are you going on feel?
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When you say “faster” what do you mean? Rolling resistance?
There’s a lot more to going fast than that. If I have to scrub a ton of speed at every corner or the bike feels unstable at high speeds, I’m not going to do well in a race no matter what the rolling resistance is. And more importantly, I’m not going to have nearly as much fun when I’m just out riding.
If a 38 has a lower rolling resistance for the same tire that is a 33 shouldn’t it be faster in all aspects you would rate a tire?
I do know smaller is better on mud
In theory, yeah. But in reality, everything beyond rolling resistance is grey area.
If I ride two tires with the same tread pattern in different widths at equivalent pressures (which is something I do when I’m trying out tires) they don’t feel the same when cornering. Because of the way I ride, I depend a lot on the casing deforming and folding when cornering. I find that with larger tires that behavior is less predictable. I can offset that by increasing pressure a bit, but then that negatively impacts ride quality. So for my style of riding, the 33s almost always present the least compromise in performance and the most confidence, which frees me up to ride faster. I really think that confidence in your equipment is an overlooked factor in off-road performance.
So I guess “faster” is a tricky thing. It extends to the bike as well - I could run a longer and lower position on gravel, which would definitely make me more aerodynamic. But I don’t think the compromise in weight distribution and handling would be worth it. Then again, for different roads and surfaces, maybe it would.
Sorry for going on a bit of a rant over these last few posts. The absolutism that gets tossed about in cycling really bothers me because there is so rarely a universal solution - “x is always faster” or whatever. So much depends on you, and the way that you interact with your equipment. That combination is what’s fast, not either one in a vacuum.
It’s all good. We are all different. What works for you might not work for someone else
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I ride in Utah and the Western US. I’ve ridden my road bike with 23 slicks on MTB trails and use my CX bike to ride single track, and all of those things are possible, but I usually ride 3+ hours. Having been beaten up by a few too many centuries on rough gravel roads in races I am not winning, I’d rather go out and enjoy the journey on a big fluffy tires in the 40-50mm range.
Stats: Lady rider, 65-70kg depending on the time of year, currently I run 700x40c 30 psi and 650x47 sub 30 psi.
And here’s a nice picture of some terrain, sometimes worse, sometimes better.
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