Dunno yet. Cat 2 / medium rough track gets the really meaningful results… the cat 1 is interesting and like 5 minutes from my house so it’s always in the mix
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Based on just those results I’d say they look pretty quick…
Wider and records the same RR as a Terra Speed which is generally regarded as one of the fastest “gravel” tires out there.
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It appears, that if/when the Tracer 50 is tested by BRR they should be the fastest 50mm tire by quite a margin ~2w.
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Certainly reasonable comments. I think at this point the conversation of “gravel or mtb” tires is largely irrelevant as to what “category” they are in.
My comment was regarding that they appear around 20% slower than a thunder Burt. For anyone that can fit either tire, the obvious choice would be the TB, except for certain instances where flat protection might be at a premium. Granted, the jury is certainly still out on the Tracer regarding its flat protection. With so many new variables, it certainly can’t automatically fall into pathfinder reputation for protection (same with the new pathfinder, at this point).
I can fit a TB front and rear but generally won’t on the rear because the risk of puncture isn’t worth it to me. I like the 47mm pathfinder pro, but I would be thrilled to have a faster 50mm, that matches the most recent gen. Pathfinder pro in puncture resistance.
Even so, it’s a hard argument to make that the Tracer is “mediocre” given that it appears to be faster than every other Specialized gravel and MTB tire.
The relative differences between the TB and Tracer are very close to the E25 Race King and the TB, and we know the RK isn’t mediocre.
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I don’t disagree with any of those statements. I suppose I should have clarified my statement to be mediocre, in comparison to the other tires listed.
Of the 6th listed, it’s tied for 4th. (Median)
The average CRR of the 6 tires is .0093, and it’s .0098.. (Mean)
Maybe, “average in comparison with those listed,” wouldn’t have carried the same connotation as mediocre.
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Awesome! Pleasantly surprised! These look like a GREAT option for those that can only fit 50mm or want extra clearance (me). I know it’s not indicative of rolling resistance but curious - how did they feel?
Can’t wait for the Pathfinder test!
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Yeah legit option.
Subjectively… I like them. Feel good on pavement and dirt. Overall good traction.
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Unless it’s about cornering of course…
Also probably helpful to think about it as reducing width on the rear due to frame limitations rather than going wider on the front for speed. This particular gravel mullet tire setup is very much a compatibility-dictated compromise when the ideal setup would be a matched set at the wider of the two widths.
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According to the Swisside gravel test, the difference in CdA is roughly 0.03 per 10mm of tire width. The measured width difference between a 2.1 Thunder Burt and a Caracal Race on BRR is 9.9mm. For the computations we use An interactive model-based calculator of cycling power vs. speed with the baseline drivetrain efficiency and air density. For rolling resistance, we use Jkarraschs category 2 gravel results.
Suppose we have a 85 kg system weight rider who has a 0.4 CdA when the bike has Caracal Race F/R. Given your 30/70 weight distribution and assigning 100% of the aero drag to the front wheel, the power to hold 30 kph is
- Caracal Race F/R: 228w
- Caracal Race F/ Thunder Burt 2.1 R: 220w
- Thunder Burt F/R: 217w
This is on rough ground - on smooth gravel the Caracal race F should win out. I think the 30/70 distribution is wrong though, the Silca calculator says 47/53.
Edit: I see I totally misunderstood your point! Anyway, this was a fun exercise and something I’ve been wondering for a while.
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Yup, its very important for people to run narrower tires on the front for aero gains, that way mediocre descender me can drop them on twisty downhills and never see them again (even when theres a flat paved section after the dh).
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It has been shown countless times that on gravel in particular, the rolling resistance saved by a fast wider tire (TB or RK) outweighs the aero advantage of going narrower.
Also, while wider tires are ‘generally’ more puncture resistant, the thunder burt is rather notoriously puncture prone. The pathfinder, although narrower and not as fast regarding rolling resistance, has one of the best reputations for puncture resistance. I can fit a TB front and rear, but I’m not at a pointy end of a race anyways where risking more flats for more speed in this scenario is worth it. I could certainly understand why podium contenders may take that risk, however.
The actual studies backing this up about aero in tires and rolling resistance have been mentioned previously in this thread. Dylan Johnson’s most recent video on the topic outlines it fairly well.
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Yes. Aero tested recently w 40 mm and 52 mm tires. They work
Yep, I’d run matched sizes for gravel if I could in most cases, just not as much room in the rear on my current bike. But there is a significant handling benefit also provides a little suspension up front. Besides cornering/descending benefits in loose conditions, a wider front tire can be a big advantage in deep sandy stuff (much less chance of that front wheel grabbing).
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RE: Aero concerns vs rolling resistance. We should always remember that aero concerns do not really matter much when one is drafting in the bunch, but rolling resistance matters all the time. This factor alone means that rolling resistance is a bigger factor, especially considering racing speeds in gravel. I am not suggesting that aero does not matter at all, many times I have been chasing, alone, to a group ahead, and am thankful for being having trained to get in a reasonably good aero position, I am just pointing out that RR is more important.
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Agreed in the limited context of tires, but aero overall still trumps rolling resistance by a healthy margin unless you are going really slow through mud or very chunky gravel. I’m pretty sure that’s what you meant, just calling it out for anyone who might think rolling resistance is a bigger factor compared to the overall aero factor. When moving at decent speeds (even in the draft), aero is still sucking most of the watts. And body position on the bike is still the biggest difference maker for aero.
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Aero overall is the biggest factor for the full system yes.
Aero of the front tyre is a small part of that larger aero penalty.
front tyre as a system, the rolling resistance benefit of the larger tyre, outweighs the aero penalty of the slightly bigger tyre.
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Generally agree (particularly when the road/gravel gets rougher and speeds get lower), but it obviously depends on how big the rolling resistance difference is vs. the amount of the aero penalty. Like most of this stuff, it’s highly dependent on course, speeds, and strengths/weaknesses of the tires being used. I recently tested a front race king vs. a front pathfinder pro and the pathfinder pro was a bit slower on a mixed surface course. Rolling resistance of pathfinder tests slower, but it was faster. I’d attribute that to being ~9mm narrower and more aero.
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No misunderstanding, had just moved on to additional discussion. And totally agree that wider probably has more rolling resistance benefits in the rear without as much aero penalty. But many bikes have more limited clearance in the rear so people tend to run a staggered setup. I look at the front on it’s own and there are certainly cases where larger makes sense with lower rolling resistance and better handling trumping aero losses. Would there be cases where you run larger in the rear and smaller in the front? Maybe, but if a road is rough enough to favor a wider tire, it’s often going to favor it front and back and having a grippier tire in the rear (compared to front) can also cause some handling challenges (ie- crashes).
edit - I wouldn’t read too much into tire wear as an indicator of rolling resistance percentage. Sure, some of that wear is related to weight and corresponds to Crr, but mostly they were faster because the rear is the drive wheel. Drive wheels always wear faster whether they are carrying more or less of the load compared to non-drive wheels.
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