The R Chung testing in the MTB tire thread shows similar results with other XC/Gravel tire comps.
The issue is that hysteresis losses are at a different scale from suspension losses. A wider tire may lose 5-7w by virtue of it’s width rolling along on pavement or smooth dirt, but a narrower tire will lose multiple times that from suspension loses on anything else due to it’s own width.
It’s much less likely a given racer can determine the best pressure for the fastest 38mm tires as opposed to the fastest 2.1/2.2 tires, because of the massive differences in losses from each type of rolling resistance. If you have to air down to extreme low pressures to limit suspension losses, hysteresis losses will necessarily increase.
It’s easy to fall into the “horses for courses” idea but the relative differences are of such different power, there’s a stronger argument to be made that the fastest 2.1/2.2 XC tires are a better general choice than the fastest 38-42mm gravel tires.
At least for right now, as I mentioned earlier. Gravel tires appear to be getting faster. The new Hutchinson Caracal Race is the fastest tire BRR has tested so far in the gravel class that has any sort of knob feature. In addition the new logo Specialized Pathfinder Pro appears to be an updated model that is slightly faster than the older Pre-2024 models.
Sure, there is short-term and long-term progression at play here, just like the MTB evolution WRT to stuff like suspension as well as tires & frames (26" > 29" > 650b > 32"? and then all the width growth for each one of those along the way.)
But I am talking more about the fact that we often see pendulum swings in these trends where there’s a point that too much becomes TOO MUCH. Suspension travel, tires, etc. have followed that trend to a degree or two and I fully expect to see something like that here. For the life of me I can’t see how a 2.?" tire on non-extreme gravel will be faster than something in the 40mm range, but that’s where science and data hopefully come in to clear the confusion & assumptions.
Either way I sit on the sidelines as I already found what I want so it’s just entertainment for me now.
DJ is always saying Pete (IRC also wicked slow) or Maxxis sponsored riders besides Keegan would be doing better if they weren’t tied to those grave tires.
I agree there’s some amount of bracketing going on, but it’s also hampered because it’s not a level playing field. We still see that the general trend in tire widths and travel is slowly trending towards “more”.
Totally agreed. My next commuter/offroad bike that will replace my hardtail will be a gravel bike with flatbars and an aggressive geometry (I’m leaning towards the Nicolai Argon GX).
As we discussed earlier, I think for those bike a frame that accepts wide tires (~2.1") on 27.5" wheels and 700c “narrow” ~45 mm tires makes sense as you’d have similar handling characteristics for both. For some reason, this hasn’t been very successful in the market.
Spot on. I remember arguing with someone on the internet (imagine that) whether you can feel a difference of a few psi of pressure. My argument was that you totally can if you are close to resonance points on different surfaces. If I ride on good tarmac vs. bad tarmac in specific places, I can feel the difference if I drop the pressure by 3–5 psi even on road tires. It gets tricky if on a single ride I ride on roads with rough and smooth tarmac. I have to decide what to optimize for.
For offroad tires this is even more true. Another factor we haven’t talked about is fun: do you enjoy being underbiked, for instance? Or do you want to have something that rolls smoothly over anything, and lets you go anywhere that XC mountain bikes can go?
I think what is happening is that gravel races have become gnarlier just like XC racing has become more technical over the years. So the bikes have adapted to those new, gnarlier races.
The most likely evolution is simply a bifurcation into different types of bikes just like in the mountain biking world. An XC bike is different from a trail bike to an enduro bike.
The next obvious step is that suspension will become more popular on some gravel bikes, and you have a blend of XC bikes (hardtail and fullys) and gravel bikes.
We are just looking at it from the perspective of speed. A lot of people in Germany used to buy hardtails for everyday use because they were robust, relatively cheap, relatively simple and the wide tires gave riders a lot of comfort.
These bikes are now being displaced by gravel bikes, at least where I live (which is, unfortunately, flat-as-a-pancake). Unless you are talking about ebikes, then eMTBs are all the rage. Who cares about rolling resistance, when you have a motor helping you?
As you correctly wrote, the pendulum will eventually swing back towards the middle. Maybe we will realize that for most intents and purposes, clearance for 50 mm wide tires are good enough and that you want to stay in the 40–50 mm range.
I did rolldown testing on them myself after seeing it mentioned in an IG comment from someone. I’m trying to get them added to the BRR voting list but no luck so far. I think they changed the casing slightly as they are more supple than the pre-2024 models.
How have the statistics looked with 2.2+ tires other than the continental race king? That seems to be the tire mentioned for the wide-tire argument 99% of the time.
Also, over say a 5 hour, 100 mile course, what are the expectations for increased finish time from a continental race king, vs one of the fastest 45mm tires?
No, the idea is that 35 mm is too narrow (starting point of the pendulum on the left) and perhaps 2.25“ too wide (pendulum reaches maximum deflection on the right), and the it reaches equilibrium somewhere in the middle.
The data I have comes from BRR, so drum. But I’ve also set some PRs on both paved and dirt (including light singletrack) on the Thunder Burts. Anecdotal for sure, but I’ve time probably 5-6 different tires on those same segments…
Yes, but why would you run a road wheel with such a bike in the first place and why wouldn’t those be your first choice for road/gravel?
Well, 2 points I can readily see is weight and aerodynamics. But not rolling resistance or overall quality of life (with bad roads, pot holes etc. pp and also champagne gravel forming ruts on descends inevitably).
For my No. 22 Drifter Gravel bike I never really liked to ride a road wheelset. It worked and I did it mostly because that was the wheelset with a dynamo (used it for Transcontinental Races). But the handling wasn’t optimal. This bike shines around 38 mm tires W.A.M. really. And so I run it on “road/gravel” aero wheels with such. Brilliant. So in a way it is at the same time prove that you would want to run a “road wheel set” as prove that you don’t need a “road wheel set” because now, finally, wheel makers (the current last to the party being Zipp) acknowledged the benefits and are willing to market these.
On the other hand again: My Canyon Exceed MTB with a pretty different geometry handles wonderfully even on tarmac and tarmac curves. And it’s the far more capable “gravel” bike than my drifter anyways. I would never really want to run road wheels and much more narrower tires on it anyways. Slicks? Maybe - but that would reduce weight and aerodynamic penalty (of a 2.2" wide tire on box rims) only very little anyways. It could improve rr a little, depending on the tire (which will be introduced more and more in the future, I’m sure).
I guess my point is: if you need a “direction” on gravel bikes because todays gravel bikes are only good / best on very curated routes or in certain locales then you wouldn’t want and wouldn’t benefit from changing it to road wheels and tires anyways. Very much so as you wouldn’t want your current XC mtb ride well on road wheels.
Somewhat depends on road surface, but this goes back to the point that bigger isn’t always better. I run 32 GP 5k’s on my gravel bike all the time for road rides and they are super smooth and fast running around 50 psi. And when I have a big MTB race coming up, I’ll spend all my time on my MTB (including group rides on the road) and run 38’s or 40’s. The typical big volume tire isn’t faster on reasonably smooth road at road speeds regardless of what kind of bike you are on.
I’m reading this discussion and find it really interesting.
Some comments:
People talk about the tire size problematic as if it is some deep, extremely complex philosophical question. It isn’t.
All its needed is testing. One picks a few segments representative of their use or race, tests different setups there and picks the fastest. Its that simple.
We have a hard time to wrap our heads around this, but even high level gravel and XC teams (road slightly less so lately) tend to suck at testing, its simply not in the culture yet. Riders are more often than not terrified of changing anything in their setup and there is too much reliance on dogma. This is changing, but will take some time.
Speaking of testing, one factor that delayed tire size evolution in road and XC was simply the lack of suitable products to test. 10 years ago, if a road team wanted to test 30 or 32c tires, only touring or CX models were available in that size. If a XC team wanted to test something bigger than 2.1, mostly enduro/DH tires were available in 2.4. This is very different in gravel, because the next bigger size is already available in a suitable construction (XC tires). This facilitates testing and will likely make this transition much faster.
Many contributors here are framing things as if these different setups are a zero sum game. I disagree for 2 reasons:
surely, if one goes too far in a certain direction, tradeoffs start to show, but there are plenty of modifications to a bike that actually increase its performance range. I’m going to use a silly example, but comparing a 1999 top notch XC bike with Nino’s Spark, there’s very little that the former is better than the later at, within the use envelope of a XC bike. Sometimes it is argued that some of the trends we see are due to the very different demands of XCO in later years, but one only has to check the setups used at XCM (those races are often glorified gravel races) and the bike setups tend to be quite similar to the XCO ones. More often than not the same tires as used. So when someone argues that, because the 2.2 tires are better in the chunk they’ll make the bike worse at champagne gravel, this is not obvious to me. Bike setup is not a zero sum game, just look at the evolution of road bikes.
I read some arguments in the sense that if gravel frames are to be designed to accept 2.2s, then the bikes will be/look weird if ones wants to put on 35s and ride some road. Keegan Swenson couldn’t care less how his Stigmata (or Highball…) looks or behaves with road tires. He wants his bike to be as good as possible on the gravel races of his calendar. Plenty of us still look at gravel bikes through this prism of a quiver killer bike that needs to kind of perform in a lot of different uses. But as gravel racing matures and grows, gravel bikes will more and more evolve to excel at…gravel races. My personal feeling is that what many people look for today in a gravel bike is rather the logical conclusion of an allroad bike and that allroad bikes will in the next few years mature and occupy that niche.
Unfortunately, it really isn’t that simple. Testing a few segments from a course that can can span hundreds of miles is not a good proxy for how different tires perform across the entire course.
To say it is not a perfect representation of an entire 200m long course I can agree with, but to go as far to say it’s not a good proxy, I’ll have to disagree. Testing will always be the creation of a simplified, repeatable model of a larger and more complex system. Otherwise it’s simply not feasible to test anything. In the end, what’s the alternative to test representative segments of an intended route ? Ride the whole course and hope it is repeatable ? Argue in a forum about it ?
Never let perfection be the enemy of good
and then all the width growth for each one of those along the way.)