Big Sugar Gravel a handful of people chose to run MTB tires. Dylan Johnson ran a Race King in the front, couldn’t fit one in the rear so was running something else. I want to say Tobin Ortenblad was another, Maxxis if I remember?
In that case, it was probably how rough it was, but also trying to run lower pressures, inserts, minimize chance of flatting when riding fast in a group where you don’t see everything coming…
This was a large motivator for the Epic HT drop bar build that I’ve posted elsewhere on this forum… Its been my hypothesis for a while now, that on a lot of gravel/dirt roads(my local ones included), a larger volume tire isn’t any slower, and in fact is faster while being more enjoyable and forgiving.
The Thunder Burt 2.1" first confirmed this, and the Race King 2.2" further validated it.
Also @oldandfast , I’ve heard of at least one person fitting Race Kings on their Mog, but clearance “Tight” so probably only works in dry conditions. 650b might give you better clearance but Enve doesn’t recommend that - unsure why and if it’s just because it’s “Not Needed”
It depends on the course. I have a 7 mile gravel/dirt segment and the 38mm Pathfinder Pros are faster than my 2.2 Race Kings. With average speeds above 15mph you pay an aero penalty with a fat tire on the front. Where did Dylan finish at Big Sugar, 18th? How about the winner or those 2 through 17? I bet they ran a smaller tire than Dylan.
Not mtb tires but I ran 700x50 Conti Terra Hardpack’s all year for gravel racing and training (on road) with Cushcore insert with good results.
They definitely feel like more of a mtb casing than most gravel tires I’ve used and they rank pretty good on BRR. They feel faster on road and gravel compared to 42 Pathfinders and various sizes of Gravel King SS and SK’s I’ve ran.
Only drawback is they’re not the most confidence inspiring at cornering on gravel but what tire really is.
I honestly don’t know how you could test for it……it is likely unique to every race / set of course conditions. The best you could probably do would be some Chung Method testing on the course itself, but even that is only representative of that test section, not the race as a whole.
No doubt that was a HUGE part of it….but it all played into it and we can’t isolate all the compounding factors.
But I am interested enough in going even bigger for some races next year that I am considering finding some 650b wheels and doing some testing.
I think you’re over exaggerating the aero penalty. This would essentially be negated by the lower rolling resistance that these top tier MTB tires offer. Per Swiss Side’s study, a 10mm increase in tire width is ~3.5w at 30km/h(18mph, which is pretty on par for the non pro fields). Knobs only add a watt or so. And I bet this all has a point where it tapers off significantly, and say anything larger than a 55mm tire is essentially very similar or within the margins that testing it would be really hard to expose. Keep in mind that this is all in “clean” air. So unless you’re solo TT’ing the race, this is irrelevant, and similarly, that larger tire would be a massive perk when you’re smacking rocks and potholes while sitting on the wheel of the guy in front of you. I’m a firm believer in aero benefits, and marginal gains, but the aero penalty of a mtb tire isn’t something I’d fret over when the upsides are so prevalent.
I was the one running the conti 2.2’s on my Mog. Yeah it can only be ridden in dry conditions, I had to trim down the tire hairs so they would stop rubbing. Going to try the 2.1 thunderburts at some point to see if I can gain a few mm in clearance, the biggest issue is actually the top of the front tire and middle of the fork.
The 50mm Race Kings are the PureGrip rubber, not the BlackChili. The 2.2s are faster.
The RaceKings have about the same grip off road as the Terra Speed, which isn’t much on loose top layers. The ride quality doesn’t get much better after a certain point because of casing tension. You might has well use the 45mm Terra Speeds if you can’t do the 2.2s - unless you’re on big rocks.
As for other tires, I’d only also look at the Thunder Burt.
I tried this for a couple seasons back in 2017-2019 - went from WTB Resolute/Rene Herse Steilacoom 700cx42/38 to 29x2.25 Schwalbe Rocket Ron and then Thunder Burt - based on the BRR testing. Same drop-bar 29er, just swapped tires and adjusted gearing slightly.
The MTB tires, despite the tests, were never as fast as the gravel tires. I think the diamond pattern and roller diameter vastly understate the real world rolling resistance of most of the MTB tires tested at BRR.
I race a lot of the same guys year after year and my races with MTB tires I was losing minutes to them when prior and after I was hanging til the sprint or dropping some as the race developed. Courses generally 3/5 surface roughness, not buff but not too bad.
I think it’s worthwhile to experiment, but MTB tires for gravel racing, here in the Southeast, were not a benefit for myself.
Yep, Tour Int clearly shows the increased watts you need with wider tires at speed. Something I’ve seen myself from my 7 mile dirt/gravel loop when comparing the 2.2 Race Kings versus the 38mm Pathfinder Pros.