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 âgravel or mtbâ tires is largely irrelevant as to what âcategoryâ 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 canât 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 wonât on the rear because the risk of puncture isnât 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, itâs a hard argument to make that the Tracer is âmediocreâ 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 isnât mediocre.
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I donât 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, itâs tied for 4th. (Median)
The average CRR of the 6 tires is .0093, and itâs .0098.. (Mean)
Maybe, âaverage in comparison with those listed,â wouldnât 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 itâs not indicative of rolling resistance but curious - how did they feel?
Canât 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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People who are putting a wider tyre on the front for racing; surely this is a little arse about face?
Yes, you can fit a wider tyre. But that tyre contributes (Iâm making this number up) ~90% of your total losses from tyre width for aero, and (well, this is a bit hard to find - but googling only gives me a source of the Continental product manager) but apocryphally ~30% of your total rolling resistance. It also has a much lower chance of needing the volume for puncture protection.
So youâre putting the wider tyre where it is least helpful and most harmful. You might get a bit more grip I guess? I sometimes run a wider front when racing EWS, but thatâs because grip is the most important feature I need.
Iâm not saying donât run wide tyres, but maybe - run matched tyres?
Unless itâs about cornering of courseâŚ
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 Iâve been wondering for a while.
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No, they are 36 mm wide external for the front and 35 for the back wheel.
Were it those, @jkarrasch ?
I actually wonder how the super wide hook flange of those new Duke rims are interacting with air flow. I think theyâve done this for superior pinch flat protection but these things are so massive they have to have some sort of influence at the tire-rim interface. But it could be anything - not terribly noticeable to an actual measurable disadvantage to an actual benefit depending on the tire model and tire width.
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My hunch with such optimizations and new trend is that they are thought of and tested and proven by clever minds and tinkerers who may or may not be connected to professional racing or even racing themselves. Of course there are overlaps like Dylan Johnson (who talks freely on his channels about his learnings - at least most of them) or Dan Bigham (who of course has to hold his cards close to his chest and has vastly more ressources as any racer or hobbyist available) and then said hobbyists who might have engineering background and know how to test stuff.
You might read some of such people here and there in forums like this or others and stumble across the odd blog. From there it gets picked up by some racers like e.g. Keegan and from pro tour teams (albeit in a more formal and longer taking process and supported by consultant services like Josh Portner from Silca runs). And only then⌠when their use is wildly and exhaustively debated back and forth in threads like this and the message shortened and repeated obnoxiously by cycling media to the point of oversimplification⌠only then you would see the crowd you mentioned on that techâŚ
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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 âgenerallyâ 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 Iâm 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 Johnsonâs 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, Iâd 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. Iâm pretty sure thatâs 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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