Both are fast tyres, but the Super Race version of the Thunder Burt has never been tested by BRR (BicycleRollingResistance.com). Only the more robust Super Ground version of the Thunder Burt has been tested (see here). Nevertheless, that Super Ground version of the Schwalbe Thunder Burt is so far the fasted MTB tyre tested by BRR, marginally faster than the Continental Race King Protection.
In principle, the thinner carcass of the Super Race version of the Thunder Burt should be faster than the Super Ground version. This is at least what Schwalbe claims. However, some tests on BRR in the past gave some unexpected results, with the Super Ground version of the Racing Ralph testing a few Watts faster than the Super Race version. This showed that it's not guaranteed that the Super Race version should be faster tyre, which is what motivated me to do this test.
Test details
I tested the tyres using the same protocol used previously, which I explained in a previous post here. As for my most recent test though, I used my MTB with its Power2Max spider-mounted power meter which measures total power. As a consequence, this was one of the best executed and best controlled tests I've done.
I tested the two tyres in an A-B-A-B manner, so both tyres had a repeated test. In addition, I also test my older 2022 Schwalbe Thunder Burt Super Race tyre first, to check that it gave similar results to last week.
Results
The results are shown again below. The results are fairly conclusive, showing the Super Race version of the tyre (plotted with purple symbols/lines) being faster than the Super Ground version (plotted in red).
This is one of my favourite tests and well done it getting those results. It takes time, money and lots of patience. I'm also very impressed your other half allows you to use your bike and rollers in the house. Or have you got a man-cave? :-)
ReplyDeleteAh, I have a man cave on the back of the garage, so that helps :-) Still, knobbly tyres on rollers make a hell of a racket, and Sarah had to put up with that drone for 2-3 hours at a time. Thanks, it tested my patience doing that testing and I was starting to lose the will to live when doing all the repeated runs, despite telling myself it all useful base training. The tyres will go to good use, and it won't be wasted money. I'll still be happy to run that Super Ground version of the tyre, because I reckon the extra puncture protection it provides compensates for the small penalty in rolling resistance.
DeleteBBR also tested the Super Race: https://www.bicyclerollingresistance.com/mtb-reviews/schwalbe-thunder-burt-super-race
ReplyDeleteStrangely contradictory results. Any idea how to explain this? Schwalbe itself also claims that the Super Race is faster.
Yes, I just read BRR's review. I was waiting with interest for that test to be done by BRR, especially because their older Racing Ralph Super Ground versus Super Race test gave an unexpected ranking between those two casings. I can't explain it. It's strange that BRR's results are different to mine and, as you said, also different what Schwalbe says is their fastest rolling casing. I would expect that Schwalbe performs their own drum testing to verify which of their tyre models is fastest. I'd be surprised if they didn't do that.
DeleteFor what it's worth I think BRR messed up by not testing consistent tire widths the way you did. Both of their Super Ground tests (Thunder Burt and Racing Ralph) were wider than their Super Races (2.25 vs 2.10 and 2.35 vs 2.25 respectively). Anecdotally, I find wider tires to roll faster.
DeleteI think BRR messed up by testing different widths between Super Race and Super Ground. You did it right by testing the different compounds with the same width.
DeleteI think you did it right using identical widths. BRR used narrower widths for Super Race and I think that threw off their results.
DeleteThat's a really good point. I hadn't noticed that previously, that both of those BRR tests were done with the Super Ground versions having a larger width than their respective Super Race versions. BRR's own GP5000 testing shows that at equal pressures the wider version on the same tyre has a lower CRR. I think that might explain why their Super Race versus Super Ground testing threw up some strange results.
DeleteI'm the same as you, I find that for real-life off-road riding wider tyres are usually faster. I haven't done any tests to prove it, but their are other factors that affect rolling resistance in real life, in addition to the tyre hysteresis losses that are measured by drum testing, that would give wider tyres an advantage when riding off-road.
Have you ever considered a rough-terrain rolldown test? I used to blindly follow BRR but I'm starting to doubt him for MTB stuff. Glad I found this post because I thought I was having cognitive dissonance. My 2.35" Thunder Burt Super Race feel noticeably faster than my 2.2" Race Kings. I need to locate a good rough-terrain hill for rolldown testing myself. Have you seen Bontrager's uneven terrain treadmill? https://www.youtube.com/watch?v=gYaWetHzejQ
DeleteI hadn't seen that Bontrager treadmill until now. That looks brilliant. I like that they can test tyres with a rider on the bike. Doing that will pick up the suspension losses that occur (also called impedance by some people), in addition to the tyre hysteresis losses that drum and roller testing picks up. I still think drum testing like BRR's tests are useful, but it doesn't capture everything. For example the way CRR varies with pressure on drum test is not representative of real life. I still believe it has some value though, for comparing one tyre against another (if they have equal pressure and widths!).
DeleteI've haven't tried doing an off-road rolldown test, but I'd like to give it a go some time. So far I've only ever done virtual elevation testing. Rolldown testing has the benefit over VE testing that you don't need accurate power measurements. I have the same problem as you though, finding a good test location reasonably close to home. Any good stretches of off-road trail normally has lots of dog walkers getting in the way!
Thanks for doing this! Very interesting. It led me to dive into the BRR numbers a bit more, and here's what I found.
DeleteBRR changed its inner tube protocol in 2023, testing MTB tires tubeless instead of with a tube. The old numbers were then recalculated using data from tires that were tested with both.
If you look at the Super Ground vs Super Race, we have that
- Racing Ralph SR and Thunder Burt SG were tested with a tube
- Racing Ralph SG and Thunder Burt SR were tested tubeless
It's possible that the tubeless conversion model doesn't work very well for MTB tires.
That's a really useful observation. Thanks very much for highlighting that, I hadn't noticed. The inner tube correction that BRR applies to the older tyres, which is a 4.5W adjustment at 25psi, could certainly be inaccurate. However, I'm not sure it could be wrong in a direction that resolves the inconsistencies for both sets of tyres, the Racing Ralphs and also the Thunder Burts. If the 4.5W correction is underestimated, for example, and it should actually be a larger correction, that would resolve the inconsistency for the Racing Ralph Super Race versus Super Ground. However, the same change to the inner tube correction value would make the difference between the two Thunder Burts even more inconsistent than the expectation that the Super Race is a quicker tyre. So it's not obvious in which direction the inner tube corrections might be wrong.
DeleteNevertheless, the mixing of inner tubes/tubeless testing and the variety of tyre widths by BRR makes it difficult to compare and creates some uncertainties on any conclusions we can draw.
Yeah that's true. The adjustments are not clearly one way or the other.
DeleteI don't think the size differences are meaningful enough to directly explain the differences in CRR. The TBurt SG at 35 psi is faster than the TBurt SR at 55 psi.
There's another variable to size though, which is that the wider versions of the tires are thinner.
The Thunder Burt Super Ground 2.35 is currently 10th in the voting on BRR and looks likely to be tested within a few months. That should answer a lot of these questions.
I agree about tyre width, it's probably a minor effect. That's interesting about tyre thicknesses. I had assumed the same tyre model had a similar thickness, regardless of width.
DeleteI voted for the Rocket Ron this month, because that's a tyre that has done surprisingly well in the past, and a tyre that I run when conditions get softer. I'll be vote for the Thunder Burt next month though, so hopefully we can get that tested. It's good to see a lot more XC MTB tyres getting tested recently by BRR.
Yep. Considering that you write
Delete"In principle, the thinner carcass of the Super Race version of the Thunder Burt should be faster than the Super Ground version."
It is interesting that the carcass isn't actually thinner when comparing the 2.1 Super Race vs the 2.25 Super Ground. Specifically:
- 2.1" Super Race is 1.7mm thick at the tread and 1mm thick at the sidewall.
- 2.25" Super ground is 1.6mm thick at the tread and 0.95mm at the sidewall.
Now, I don't know how accurate these BRR measurements are, but that is at least consistent with the story that the thinner casing is faster. For reference, when looking at the Racing Ralph, we have the following measurements:
2.25 Super Race: 2.2mm tread, 0.95mm sidewall
2.35 Super Ground: 1.9mm tread, 1mm sidewall
In fact, if you just take all the 5 tested modern Schwalbe MTB tires and compare the tread thickness, you get the correct ranking of their rolling resistance. If this theory is correct, a 2.25" Thunder Burt Super Race should be even thinner than 1.6mm, and even faster, and the 2.35" faster still. It will be interesting to see if this pattern holds up when the Rocket Ron is tested.
That's really interesting. Like you said, I don't know how much of that is measurement tolerance by BRR. For the Racing Ralph at least, the thread thickness difference of 0.3mm is probably greater that measurement tolerance, I would have thought. Then, it would also be interesting to know if those differences are made intentionally by Schwalbe, or whether it's just manufacturing variability and a coincidence that the thicknesses vary with tyre width for those two pairs. More data from the forthcoming Rocket Ron test, and hopefully later the Thunder Burt will be insightful.
Delete