TLDR/?
I find it pretty interesting that many people are still referring to this tire width discussion as a zero sum game of âif the suspension losses make up for the added rolling resistance in asphalt/smooth gravelâ. The pivotal point here is that the fastest XC tires test as fast or faster than gravel tires on asphalt and smooth gravel, and are faster anywhere else. This notion is sometimes a bit hard to accept as it flies in the face of "common sense "
If youâve ever raced tight circuit crits, this patently isnât true.
I think Haas raises some very valid points. He also has tested quite a lot with a pretty robust methodology.
- the impact to repeated changes in speed is never quantitatively measured
- rolling resistance measures on a smooth drum do not really replicate the realities of riding on technical terrain
- weight on the outside of the rotating mass is the most critical for both climbing and acceleration (this hasnât been âdebunkedâ, just misunderstood)
- the benefits of comfort and compliance from a wider tire can be offset by rider skill
There is likely a sweetspot, and like anything it probably goes too far the other way, before coming back and settling somewhere.
The current methods to measure how âgoodâ a tyre is, are far too simplistic to draw such absolute conclusions.
If weight was such a big factor, above all else, then all World tour bikes would be exactly at the UCI weight limit, certainly at the biggest race TDF. Same in XCO/XCM. However, very few are and most are well over. Particularly in XCO/XCM where bikes have become heavier not lighter over the past 5 years. Even though technology and design has improved the benefits of other marginal gains has trumped having the lightest possible bike.
All else being equal, the lighter thing/part is marginally better. However, if you can trade a bit of extra weight for a bigger marginal gain elsewhere, then that is a trade off worth considering. Same when a thing/part is less aero. As long as itâs an overall positive itâs the better choice. Itâs never absolute and will generally always be âit dependsâ based on conditions, course and how you intend to race it. For example, aero bars are LESS aero unless youâre actually in the aero position. So often I see gravel bikes with aero bars in races and theyâre rarely if ever in the bars, even when taking their pull at the front 
.
How to measure these differences and compare? Well, the weight scale is the easiest and all other marginal gains are both difficult and expensive. This is why weight has traditionally been the holy grail but is more recently loosing its value.
- World tour speeds dictate that aero is a bigger factor
- The climbers will ALWAYS use 6.8kg bikes for stages where the climbs are the critical moments⌠even though they often ascend faster than most people here ride gravel on the flat
- Thereâs actually fewer short sharp accelerations in world tour races than technical (European) gravel races
- They still will go for the lightest wheels available to them for a given depth. Reducing the weight of wheels has been the primary target of manufacturers for the last few years
You are kind of right that a net advantage is the better choice⌠but actually the best choice is usually the option that gives you the greatest advantage when you need it.
Letâs see if the aero111 tyre gets used at all next year. It has lower rolling resistance than a GP5K TT, and in pretty much all circumstances would be slower over a full course TT⌠might be great for critical moments thoughâŚ
That argument falls apart when you compare it to XCO/XCM. There are actually fewer short sharp accelerations in European gravel races than technical XCO/XCM races. Yet racers have ADDED weight to the worst possible area, the wheel in the form of tire inserts. Clearly other marginal gains are believed to be better than weight.
Bingo. There is actually some good published research on the power demands of xco racing too.
Been racing crits since the late 80âs, thanks. So if weight is such a critical issue in them, I guess everyone is racing with low-profile, super-light carbon rims, right?
Sure it hasâŚ.and even if it hasnât, physics gives us the answer. It can be calculated.
I donât think anyone is arguing this point. It can, however, give your directional data.
Again, no one is disputing this. The point being made is the energy required to accelerate a wheel that is already in motion is not the same as the energy required to accelerate it from a dead stop. Further, the energy required to accelerate a wheel in motion with a larger tire is more than offset by the overall gains of that larger tire across an entire ride.
Irrelevant to this discussion. We are talking about which tire is faster. Comfort and compliance is a side benefit.
Of course every choice is a compromise of some sort. Iâm not suggesting weight is more important than all other factorsâŚ
Tire inserts have a negative impact on performance but the cost/benefit of a race ending puncture may deem them necessary. Not every rider uses insertsâŚ
Not to mention the race to lower weight in XCO IS still very prominent, let alone in pro road racing where it is not just prominent but still one of the (if not THE) most critical factors. That is why we have seen the move towards âone bike to rule them allâ where they try to develop the most aero bike that is capable of hitting UCI weight limits. Next year there is a move back towards full aero bikes, but primarily because they can now do so with little penalty above the limit, and pretty much every brand has a UCI weight limit option available.
The choice between aero and weight is made primarily on the basis of the critical part of the race for a particular rider (if they are sensible).
Thatâs starting to drift off topic a bit, but the point is that the best setup is not necessarily the net fastest setup.
Haasâ point is that in his experience, if asked what tires he would want for the race defining moment when attacks start flying on a steep climb, he wouldnât go for the widest tyres possible (based on his repeated testing of exactly that scenario).
I donât profess to know what the sweetspot is, but I can see the problems with the oversimplification of the âwider is fasterâ argument.
Except their obsession with weight is not based on science or data, it is based on âfeelâ and traditional beliefs.
Thatâs quite the assertion, but itâs not relevant anyway. My point was countering the statement that world tour bikes arenât weight focussed. They certainly are.
Who said they werenât?
You seem to be making strawman arguments and deflecting while tacitly admitting that the point others are making, namely the overall gains in one area can offset the losses from extra weight.
Here:
Yes, thatâs exactly what I am admitting⌠the OP question of this thread is âis a MTB tire the fastest and best tire for gravel racing?â
There are absolute statements made here that it is both the fastest and best. Nathan Haas has suggested otherwise, I am pointing out that his logic seems sound and I agree with it in principle⌠at least, I agree that there are some logical shortcomings in the argument âforâ. Fastest (over a full course) is not necessarily the same as fastest when it really matters, which may well determine âbestâ.
I think Haas raises some very valid points. He also has tested quite a lot with a pretty robust methodology.
Where?
- the impact to repeated changes in speed is never quantitatively measured
- rolling resistance measures on a smooth drum do not really replicate the realities of riding on technical terrain
- weight on the outside of the rotating mass is the most critical for both climbing and acceleration (this hasnât been âdebunkedâ, just misunderstood)
- the benefits of comfort and compliance from a wider tire can be offset by rider skill
Both point 1 & 2 are taken into account by R Chung methodology. There are also other tests used, and other trials that have been performed in real world conditions that align broadly with roller data. Tom Anhalt was working to address this 10+ years ago.
Weight and rotating mass are clearly understood and modeled. They are at a different scale than suspension losses.
They cannot. Rider skill can offset some of the suspension benefits, but again itâs at a different scale. The best tire is going to help every ride, regardless of technical skill.
The current methods to measure how âgoodâ a tyre is, are far too simplistic to draw such absolute conclusions.
If this were to be true - Why have world tour teams moved to 30mm+ tires? Why are XC racers using 2.4" tires? How did they move from 1.9" tires to 2.1/2.25 then 2.35?
What is the ideal gravel size? Gravel has been getting bigger in line with frameset tire clearance and quality of available tires in a given size. 20 years ago 33-38 was the size where the best tires could be found. Then it was 40-42, then 47, now itâs 52.
Haasâ point is that in his experience, if asked what tires he would want for the race defining moment when attacks start flying on a steep climb, he wouldnât go for the widest tyres possible (based on his repeated testing of exactly that scenario).
The widest tires possible arenât under discussion. Itâs very specifically the fastest XC tires in 2.1/2.2.
For discussion, equally as often the race defining moment is a descent. What tires does Haas want for rough technical descent where the time difference between the front and rear of the pack is potentially 20 seconds over 150 meters?
Listen to the podcast.
Youâre assuming that my position is that skinny tyres are faster. Thatâs not the case at all.
Yes agreed, they tend to mean the same thing.
Youâd have to ask him. I think his point from the podcast is that his technique level is good enough that he doesnât need a wider tyre for technical reasons, whereas an amateur might. BTW at that level race defining moments are very rarely on a descent.
This is a factually true statement. That doesnât mean that many WT riders arenât still âweight focusedâ.
Those statements have been based on data and testing. Hass is âsuggestingâ otherwise based on beliefs.
You seem to be getting hung up on the idea of an âabsoluteâ answerâŚthere will never be an âabsoluteâ answer. It will always be course dependent, largely based on how much asphalt there is vs. gravel.
Directionally, however, the data is very clearâŚfor the majority of gravel riding, an XC tire seems to be the fastest choice currently. Does that mean it is the right answer for every scenario? NoâŚbut in most cases, it probably is.
No, tested. Did you also not listen to the podcast? Here it is: https://youtu.be/NsG1UwhHXxo?t=454
I donât think anyone is going to spend 30+ hours listening to podcasts trying to figure out what testing he did and what his results were. There isnât enough information in the title or summary to even get started. What episode, at least?
If he is testing with robust methodology a podcast is the absolute worst place to disseminate that information. Does he have a youtube channel?
Youâd have to ask him. I think his point from the podcast is that his technique level is good enough that he doesnât need a wider tyre for technical reasons, whereas an amateur might. BTW at that level race defining moments are very rarely on a descent.
Thereâs no way to say this without sounding rude, but reality does not seem to back up this statement.
I donât think either one of us has the data to say where the race defining moment most often appears in gravel races at the professional level.
Me or you, no. Nathan Haas, yes for sure.
Itâs on youtube, see the link above. The exact same way that DJ disseminates his information. He did the testing with Chad Haga, for anyone who still doesnât want to listen themselves.