The marginal difference was fairly small, the 50mm tire he tested in the wind tunnel was the Pirelli Cinturato H 35-40-45-50mm v. the 53mm Race King.
I’m not sure this is generalizable to width alone. It’s within reason that other 50mm tires would scale differently. From the Swiss Side “Knob-Ness” testing we can see the difference may also be entirely due to the tread design.
Near the speed he tested (32kph/30kph) the tire surface and sidewall would be responsible for more than 2w of aerodynamic drag (how much more for 50mm+ tires I’m not sure as that test was specifically 35mm tires). Even the lower value from narrower tires is much greater than the marginal difference between the tested 50 v 53mm.
The Thunder Burt is also relatively faster than the Pirelli so it would be within or better than the margin compared to the Race King, which is a tire that essentially no longer exists. The Thunder Burt appears to certainly be faster than the fastest Dubnital and given it’s relatively narrower actual width, makes a good counter-argument to the initial wind tunnel testing.
50mm may have been a dead-zone in the recent past but I think it’s certainly not anymore. I will be curious to see how the new 50 Caracal Race compares for instance. Although the 50 G-One R Pro appears fast enough that it also refutes the dead-zone idea.
I think it is important to not read too much into a measured watt differences of 1 to 3 watts. At the point of a difference like that, I am more apt to consider other aspects of tire performance, like handling and grip, as a few little watts are pretty inconsequential. For example, saying the Dub 50 is “slow” is pretty misleading really when it is near the top of the RR rankings, much faster than the Specialized tires, for example, and quite close to even the Schwalbe RS and RX in similar sizes. consider that many much slower tires (Specialized) seem to win some races, compare the 50 mm Tracer to the 50 mm dub, for instance… I am wondering if the Pro version of the Thunderburt will have casing changes, or if it is just the Super Race with a name change…
Random thought: what if the new Crux comes out and is super mean and aero and has MTB clearance. What will the pros run? Spesh really doesn’t even have any fast gravel or MTB tires right now do they?
There are gravel races where I second guess my preference for running MTB tires. Today was not one of them. 100 mile gravel race out of Emporia, KS (Unbound gravel territory) with a mix of fast smooth gravel and plenty of chunky selective stuff (with some extended steep climbs). When you are climbing in that loose gravel that is the size of golf balls, big volume tires with low pressure are like cheating. Those sections were the difference in the race today.
How were the roads? I know this race isn’t necessarily on the Unbound course. Seems like Emporia has had normal rainfall so far this spring so hopefully that continues.
I will have a backup set of Schwalbe 45s if we get wet conditions (RK are horrible on wet gravel/dirt). I will trust them to re-route over extreme mud pits.
Also regarding potential new Crux and tire choice… I’m sure someone could pick some interesting notes from Traka setups this year w new bikes v last year on old bikes, I haven’t looked close yet.
I noticed the Spesh Pros all opted for the Pathfinder this year vs Tracer last year. Found that to be interesting. Beers flatted the Tracer at Unbound last year and seems to be trusting the Pathfinder more now. Wonder if it has better puncture protection or if the Pros get special casing or something.
Roads for the race today were fine. Just super chunky and loose compared to what you see at Unbound (after everyone pre-rides/drives and mashes everything down). But no rain since monday. Just the typical water/rocks at the bottom of rollers where you hold your breath hoping you don’t slice a tire bombing through it.
I’ve been up here riding for the last week, including the La Grind stage race course and some roads that may be part of the 200 course this year. I hit a few mud sections last weekend and early in the week after monday’s rain. Nothing extended, just some spots that quickly loaded up tires and forced a little walking/scraping. It really just depends on what the course is and where/when the rain hits. Most of the course dries pretty quick and many sections don’t turn into peanut butter. But if it rains right before/during the race, expect some mud and walking.
And yeah, if it’s muddy, I won’t be running 2.2’s. My bike has proper clearance for 2.2’s. but more clearance is better. Even if the mud builds up, having more clearance makes it much, much easier the clear quickly. If you can’t scope mud out with your fingers, you’ll be screwing around with a paint stick for minutes trying to get rolling again.
Interesting test here specifically because they used Schwalbe’s tire test lab.
One important thing this test provides:
None of the tires were as tall as they were wide. The average ratio of height to width was 91%. Meaning a 45mm tire would be 41mm tall. This is not hugely important, but tire height difference can be enough to make/break the value of a tire.
Otherwise, the limits of roller testing can be seen here. The Schwalbe tires generally tested significantly faster on the Schwalbe roller relative to their BRR result than most of the other tires. Which should be expected as that would be assumed to be their design guide.
I’ve added some columns to show the relative difference in speed between the Gran Fondo/Schwalbe roller test rating and Bicycle Rolling Resistance rating. The two rollers and test protocol appear different so this is more of a curiosity, or to re-iterate the importance of evaluating many sources as well as the tire system as a whole.
for real. Outdoor testing is not that precise. Margin of error has got to be at least 10w. Too many variables that can’t be 100% controlled. Not saying the Chung method is not a great source of info, but its not perfect
While there are differences, I had a pretty similar take away b/t the Grand Fono test, BRR, and even John K Chung test:
Schwalbe seems to be the best all-around gravel tire brand right now. Can’t really go wrong with TB, RX, RS, or even R. Pick your poison depending on terrain. I have been running RX and really enjoy them.
Conti: Can’t really go wrong with Conti tires. All test solid. I think Dub in 50mm and Terra competition in 45mm might cover you for just about every type of gravel race. I have run the Terra speeds and like them, but they wear down quickly. Keen to try the Dubs and Terra Comp next.
Spesh: I am still unsure if Pathfinder is fast lol. I loved the previous gen, but the testing on the new model has made me second-guess the new version. However, Grand Fondo tested it as a very fast tire. But Spesh teams seem to be winning on it, so it has to be solid. - All other: Everything else looks totally fine and offers different strengths. Vitorria sounds like a great ride quality, for example, other brands seem like they are slower but offer valuable strengths in other areas like puncture protection or grip. These are things that won’t show up on rolling resistance but might be just as important when racing. Other than WTB I feel like you really cant go wrong nowadays if you are racing.
Great post. It seems that both the testing of gravel tires has improved significantly over the last few years, and manufacturers have also done a reasonable job meeting what the consumer is looking for. Obviously some gaps, but right now there are a LOT of great options out there for tires on a gravel bike, from 40’s to 2.2 (or a beach rider 2.35, if that’s your thing ).
I’m running 50mm RX’s on my race wheel set this year and very happy with them. I had a 50mm front RX and rear 47mm pathfinder pro for unbound last year, and was also very happy with the setup.
Schwalbe has particularly knocked it out of the park with their latest lineup. I’m excited to see what this new thunder burt has in store.
I’ve been running the 55mm G One RS Pro’s on my gravel bike this year and the 40mm GR One RS Super Race on my road bike this year. I’m in Ohio where the gravel can get rough but punctures usually are not a major issue. On the gravel the RS Pro’s have been great, but you more or less forget you are on a gravel tire when you hit the road. I did a recent 1 week training camp in Maui on the 40mm G One RS Super Race’s and they were fantastic. Maui can be hard on tires with the small volcanic rock boring through the tread, but didn’t have any issues including on the chopped up East Maui Loop.
The flat protection of Schwalbe’s gravel tires in the Pro casing anecdotally seems pretty good. Multiple high finishing Pro’s ran them in Unbound last year. Cam Jones ended up running a 50mm G-One RS in the front and then the 45mm RX in the rear. Karolina Migon Schwalbe Thunder Burt 2.10 front and 45mm G One RS in the back. She had been pre-riding on a RX in the front but switched to the TB for race day. Again anecdotal, but it seems I heard of more folks flatting on Dubs than on Schwalbes.
It’s really hard to figure out if any of these tires is measurably more durable than others on a given course. I did a stage race last weekend near emporia on roads that are common for unbound. I do it every year and do a bunch of pre riding on those roads also. Ends up as ~600 miles of “unbound” gravel over 9 days. This year, not a single flat or puncture (first year I can say that). I ran race king 2.2’s every day except the final stage Sunday when I ran rs pro 50’s. The only flats I saw in our group were on rs pros and both guys had major cuts requiring tubes that cost them big time. There was a kid that rode away for the win both days running thunderburt super race casing, no tire issues. another guy on race kings had some sealant spraying a bit, but sealed.
At some point, all you can do is pick the best lines and pray.
Between racing unbound, la grind, and pre-riding, I’ve ridden over 3k miles of gravel around emporia in the last 4 years. Here’s my experience-
S-works pathfinders were most prone to flats, really fragile. Pathfinder pros were ok, but still a few flats. Race kings were better per mile than both, but the one time I flatted was my only flat I’ve had at unbound in 3 tries. I don’t have enough miles on rough terrain on the rs pros to have much opinion, but watching those guys flat out last weekend wasn’t a positive data point. I’m really not sure how to form an opinion besides anecdotes and riding a bunch of miles on different tires. With my experience around emporia, big sugar, and rule of 3 riding race kings, they are my current go-to for speed and durability on chunky courses.
I run a TB up front for all my training miles and we go very hard and fast through super chunky gravel and I’ve had no issues. I did have a flat on my rear 47 pathfinder and also broke a spoke this week on my reserve rear wheel.
My riding partner also had a flat on a rear TB this year that was too big to be patched.
I’d be hesitant to run a TB in the rear on areas prone to rough/chunky terrain. Less concerned on the front.
How did you rate the RS on the pavement? I am tempted to make it my go to training tire as well as race tire but have heard it’s squiggly on the road, esp when cornering, due to side knobs?
I’m back for another season on the RX Pro for the high alpine/rugged type gravel races we have in Colorado. I have a Challenge Getaway Pro for the rear when it comes to a gravel race with more pavement and smooth roads (Pueblo for example). But that’s more or less due to the limitation in rear clearance on my 2020 Crux. I’m hoping the RX Pro 40 will fit alright and if it does, I’ll just leave it on for the summer. The Getaway is a good training tire.
Truth be told, the race next weekend (Wild Horse Gravel) might be better suited for my Epic due to how rough and long the descents are. Nearly every strava ride from the race last year was: shoulda raced my mtb or a suspension fork etc. I don’t see myself climbing any faster on the Crux vs the Epic and I could toss a 36 ring up front for the flats - though, outside of the neutral start, there isn’t much. It’s basically neutral, up, down, up, down finish.
I haven’t had any issues with the 40’s or the 55’s. That being said, Maui was super overgrown last week with the grasses along the road being super high from all the rains. It made visibility around corners on the West Maui Loop (narrow hilly sections) tough to see oncoming cars, so I was being a little more cautious on the descents. However wet or dry, traction held and just having a 40 underneath me was pretty confidence inspiring.
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