Yeah, everyone has been grappling with this concept all year.
Think of it this way, the fastest XC tires are (able to be) constructed to a finer balance between speed and puncture protection than most of the fastest gravel tires. This seems to be changing, but it’s always going to appear to be a lag based on the BRR historical results.
Otherwise, the BRR Mountain Bike testing tab has wildly out of line pressure test values. 25-55 is much too high and should have been corrected to a more reasonable pressure range as he did with CX and Gravel tires a few years ago.
25psi for a MTB tire (even on pavement) is much closer to the maximum pressure most people are going to run, than the lowest pressure.
BRR also tests the MTB tires on a really narrow rim…their testing protocol is invalid. Pressures too high on a narrow rim will make the tires shape be unlike the shape it holds when being ridden in the real world, so the results don’t matter.
And keep in mind, Keegan had a mechanical this year (rode on a flat, solo, for a while). Had he broken the record, no telling how many drop bar mountain bikes we’d see in 2025.
This is whattaboutery. Racekings have totally acceptable puncture resistance, and none of the ‘gravel specific’ tyres do much better.
The only qualification I think that needs to be added to @oldandfast 's closing of the discussion is 'until Continental (and others) bring out their 2025 tyres.
Shocker: The Race King is the fastest gravel tire. Among the tires tested, the second fastest was the 2.4 Peyote. The test was less kind to my Terra Hardpacks, as these were actually slower than the 45mm Terra Speeds.
Additional take away: The increase in CRR when going from category 1 gravel to category 2 was twice as high on the narrower tires compared to the Peyote.
I’ve been following this on Facebook and while it’s an interesting experiment, the fact that he is unwilling to share the tire pressures he used makes it more of a curiosity than a useful trial to generalize.
The Race Kings have shown to be fast in a bunch of tests. And from my own experience, they’ve been the fastest MTB tire I’ve ridden. If I could fit them on my gravel bike, that’s what I’d ride.
I like what hes doing, but those wattages are so close…i think the margin of error has to be ± 10 watts at power that low. I hope hes not using gps for speed, as that would also introduce more error.
While I would be he first to being wary on the many caveats of the diverse testing methods we have available you also have to be a bit practically orientated.
If you run enough test repeats (each back and forth or each lap already counts as one and one of the many beauties of the chung method is you actually ‘see’ what kind of errors happen along each meter of your testing) you can get reliable differentiation between test set-ups.
Also it’s the Chung Method and thus quite the gold standard for such tests. You really can’t get better as this. Especially not with roll down tests and the like.
And third - it’s another data point in the list of showing what good XC tires can do and especially in regard to the Conti Race King which I tested with this method myself and also listed literature which tested several tire modes over a typical XC course. Also with the Chung method. Which show again and again: yes, drum testing shows only part of the equation but it can reliably (at least more often than not) rank tires in accordance to their real world rolling resistance performance.
This one is just for the forum and the casual reader: Sure - depending on your discipline and riding style you might have diverse preferences and needs in addition to just a fast rolling tire. And you might weigh those higher than the rolling resistance. And that’s fine. Ultimately one has to like a tire. I e.g. like easy rolling tires sapping me the least amount of my puny watts.
Since the Conti Race Kings 2.2 won’t fit in my Crux, but Thunder Burt 2.1’s apparently will, I am likely going to give them a shot next year.
But damn, someone really needs to find a way to name tires without all the confusions. Super Ground, Super Race, with Addix Speed compound, without, etc.
Can the MTB guys help me out? It seems like the fastest option is actually the Super Ground with Addix Speed compound…which is weird because you would expect the Super Race (w/ addix) to be faster (and the Super Race is lighter).
Can anyone confirm the above that the Super Ground Addix is the fastest version? I know Dylan and others have said “just get the one with the red stripe”, but it seems that indicates the Addix compound and is therefore on both the Super Race and Super Ground versions.
I really appreciate all of the work you’ve done and have spent hours on your site.
One comment I saw in a different forum was concerning tire circumference when reducing pressure. Since the speed sensor is dependent on an accurate circumference to calculate speed, this person felt that by reducing pressure, thereby reducing circumference, and then not re-measuring, all calculations favoring lower pressure were simply due to this error. Does this seem plausible?
You have to dig into it, but its basically the tread pattern, the casing construction, and the rubber compound. Just go to bicyclerollingresistance.com and pick out the faster of them
Actually when I was super deep in the rabbit hole on aero- and rolling resistance testing I was also in contact with Sebastian Schluricke and he gave me further insights on how aerotune copes with GPS imprecision and how actually using gyroscopic speed sensors (the ones you wrap around your hub) would improve stuff or rather should improve stuff. For Aerotune especially, there is going a lot of very in depth calculations and matching of sensor data going on. As that is precisely one of the major hurdles you face when integrating all that stuff. Even without but also all the more with seperate aero-sensors or pitot tubes etc.
Long story short - for my testing (with aerotune as well as with the chung method I found I could get better and in case of the chung method even visually more sense making results when using GPS instead of such wheel-revolution sensors. You can go into a whole rabbit hole for these kind of sensors alone, as well. And it’s not only (or maybe even the least) the tire circumference of the tire. That one is mostly taken care off by the sensor or the cycling computer you pair it to by itself. Or you enter it manually.
