Not sure. More people are running them
@joshcroxton I enjoyed the article. Is there any way to see a straight up CRR value from these tests?
The deltas seem to lineup with what I’ve done outdoors on cobbles.
Unfortunately not. With the way the pedalling efficiency rig works, it gives total system loss rather than crr. I tried reversing the equation too, but couldn’t get it to make sense. Was getting ~0.08, which was way too high.
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FWIW my outdoor cobble CRR values have been from .007 to .013 across 3 courses. Pretty high.
.08 would be wild.
My Schwalbe Thunder Burts in super-ground / 2.1" are ordered and on their way. In combination with my 165mm crank arms, I’m drinking all available Kool-Aid.
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I’ve gotten some really good Chung testing runs done over the past two weeks. This round mainly focuses on aero Comparisons between two different tires (caracal race 700 x 40 and thunder Burt 29 x 2.1) and two wheel sets ( stock Reserve and Hunt Limitless gravel Aero)
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Nice work!
Thx again for those. I probably ran a dozen tests, just on that one set of tires.
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This stuff is my jam, so I’m glad I could help you get some good data.
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Great stuff again John, asking the right questions.
For reference, the Hunt Limitless 40’s are 30 external, so the Caracals also bulge out. I think these results align with what I’ve been suspecting for a while. Once you get away from
external width ~= tire width:
- There are real aero gains from deeper wheels, although less than with optimized width.
- This benefit is pretty much independent of the tire.
This is also basically what Dylan found in the wind tunnel. The 35’s were obviously more aero than the 2.2’s, but the benefit from going with deep wheels was pretty much the same with both.
For this reason, I’m a bit sceptical that there are much to gain by getting 303 XPLR SW’s or Dylan’s new 43mm external wheels for MTB tires, compared to a modern road rim. The wider internal is a small but real benefit, but the tire is still much wider than the wheel. The industry needs to get working on those 55mm external wheels 
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Far as I can tell, the Caracal Race and Thunder Burt are easily the fastest in their size for gravel tires.
Link below shows what their overall performance looks like across a mix of pavement and medium
rough gravel at midpack and pro speeds:
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Just watched a Keegan Swenson Stigmata bike check at Ben Delaney’s YouTube channel and he’s running some Maxxis Maxxlite 29 in ONE70 casing, 29x2.0. I don’t recall ever seeing those ? I mean, I know Maxxlites used to be a thing, but not with this new casing
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I’ve gleamed this from BRR so spent last year on Thunder Burt Suoer Ground 2.1 on both my gravel bikes and got a pair of Caracals after BRR tested them to have for this season on the lighter and stiffer bike.
It’s great to see your tests validate the drum results in real world and on gravel and add a data based pavement/gravel split to an expectation that narrower Caracal does best on tarmac heavy course and TB on off road.
The other so-what looks to be that the loss on tarmac with wider TB vs narrower Caracal is minimal. So opting for wider tire all the time makes sense. Is this one of the key takeaways? (Why would anyone use Caracals if they can fit Thunder Burts or Race Kings?)
Would be amazing to have a 3D version with added elevation, and I have a question: is it possible to use chunging on a course which is just an uphill segment? If I ran these tires on a paved steep uphill and off-road steep uphill segments to determine how much better a firmer and lighter tire may or may not be vs a heavier squishier wider one?
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Maybe there is a petition to be started to bring back ultra light XC tires - Maxxis Maxxlite and Schwalbe Furious Freds?!
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Based on the most recent bonk bros podcast, they mentioned that Keegan was running a discontinued tire.
I ran the rattlesnake gravel grind yesterday and the course was vastly more technical/rougher than years prior. VC Cyclist will have a video coming soon.
For the race I ran a 2.1 thunder burt up front and a 47 pathfinder pro in the rear. Despite lots of sharp jagged rocks and cactus lining the sandy & rough sections, I had no flats. I absolutely loved the combo and will likely run it at unbound and big sugar.
I will say that the front felt a bit squirrelly in the turns. I thought it was largely just my inexperience, but also heard Dylan mention the same in the aforementioned podcast. Aside from turns it did great in the high speeds, technical, and sandy sections.
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The best way for that is Chung test (or just use the coefficients on my main blog) to get aero and/or rolling values then plug the setups into analytic cycling or similar calculators at different gradients and the respective weights. Works really well.
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One70 casing was around years ago for this tire. Would love to find or borrow a set to run a test round on.
Wasn’t aware that the ONE70 casing was available back then. Thanks, that explains it
Conti is launching a new bigger gravel tire, the Terra Adventure.
https://www.instagram.com/p/DHnWiwVJugU/
From the drawing with the full Terra range, it looks massive, clearly bigger than the Hardpack. But on the real-world picture it only looks like a 50.
The writing on the side is identical to the Speed and Trail, with Adventure in yellow. This is unlike the Hardpack which has Hardpack written in white. The Hardpack is the only PureGrip compound tire in the Terra range, so this could be a Black Chili tire. That said, the name and marketing direction doesn’t really indicate that it will be similar to a lightweight XC tire.
It has a lot of closely spaced large knobs which should be good for puncture protection. Looking forward to seeing what it’s really like!
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Details are up on the Conti website here: Gravel Tires | Continental Bicycle Tires
Doesn’t appear that the new Terra Adventure is offered in Black Chilli.
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