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wheelmonkey wrote:I think I'm going to have to end up doing my own testing. Only one lab can be right, and I'm really curious who it is.
ccand51997 wrote:Yes yes yes yes!!!
Honestly, to anyone who has followed the BRR site from the beginning, this really is not a question. BRR is one guy, with one method, for ten years. No one has done it as long, or as consistently. There are a couple of others (a company that if focused on road/TT in England) that also do good work but BRR is the standard.
Jarno recently converted all his tires to reflect the differences when run tubeless so his site is even easier to use. The difference between the G One RS and the Pathfinder pro is 4 watts or so, ie 8 watts. For a pro pushing more than 350 or more that is a much less significant difference than someone like me doing 200 watts or less.
Reading anything into what a pro uses is useless. The guys at Zipp wheels put Alberto Contador on their new spoked rim and showed, conclusively that it was faster than ACs old tri-spoke in ABAB runs. He kept racing the trispoke because he was convinced it was faster by feel.
Finally, not that I would discourage someone from doing some testing on their own, but in the end you will discover why this business is so tough. It is really hard to parse out RR from all the other noise while cycling. Not impossible, but really hard. On my tri bike I can go out and hit consistent five minute laps within one second of each other using a Powertap wheel, but you have to do that often enough to develop a level of confidence in your methodology. I've had times where I banged out three or four perfect laps, changed tires and had the wind shift on me so that when I go back to the first tire, it is not on par with the first laps. And sometimes you feel like your results are really good and then go try it again and find out they were crap.
Using BRR and realizing the limits of his testing is a far better way.
wheelmonkey wrote:@thumper88 respectfully I am not convinced. I don't think that only outlier tires beat the Pathfinder Pro at BRR. For instance, the Pathfinder Pro is beaten by 40mm Gravelking SS TLC and 40mm Gravelking TLC in BRR's testing. I think Gravelkings are real tires, not outliers. At velonews, the pathfinder pro beat every gravel king tire on test, including gravelkings at the same tire width.
I think I'm going to have to end up doing my own testing. Only one lab can be right, and I'm really curious who it is.
thumper88 wrote:A little more food for thought here:Probably sponsored by Vittoria.
http://bikeblather.blogspot.com
And just to show how muddy the water can get, this one has RR testing but is more of a beauty contest. The winner wasn’t particularly good at anything important:
thumper88 wrote:And just to show how muddy the water can get, this one has RR testing but is more of a beauty contest. The winner wasn’t particularly good at anything important:Some things, like comfort and handling, are hard to quantify. I've tried too many bike tires and found more than a few which look good on paper but just don't work for me. Maybe some enterprising bike shop will start renting tires for a week, that would be a big help.
CRR, at optimal pressure: Pathfinder 38 -- 23w
Schwalbe R 40mm --24.2w
SO: Pathfinder 38 is 1.2 watts faster at optimal pressure
Velo News: no optimal pressure stated but:
Pathfinder 38mm is 0.1 watts faster at 36 psi
And 2.6w faster at 43 psi
Average edge of these two pressures is 1.35 watts.
We can call that identical results or worst case? Say it is within the margin of error. Even if you DON’T average the two pressures from CRR.
The full two sets of rankings -- for this question -- aren’t useful, just cloud things, as CRR has much, much longer list of makes and models tested. And if you drag the 42mm Pathfinder into the discussion the methodology suffers as the construction may be different from 38mm and it is much much larger -- the Pathfinder “38mm" is identical (just 0.1mm difference) to the Schwalbe “40” R in width. The Pathfinder 42 meanwhile measures nearly 45 on my wheels.
So I’m not sure what we’re even really talking about here.
@thumper88 I had to read your post a few times and got lost, so I went and made a spreadsheet to get this sorted in my head. Admittedly there is a lot going on, so I put both tables into a spreadsheet for myself to try to make things a little more simple.
As concise as possible:
BRR shows that the Gravel King SS has a 18% RR advantage over the Pathfinder Pro
VeloNews/WheelEnergy shows that the Pathfinder Pro has a 8% RR advantage over the Gravel King SS
There are numerous tire pairings across the two test methodologies that show big re-ordered gaps like this. Imagine the Ford F-150 got a 5-star crash safety rating from IIHS and a 2-star crash safety rating from Euro NCAP, and consumers wanted to know if the F-150 was safe. It's like that. Consumers would, reasonably, start looking at the differences in testing methodologies and start wondering who was right about vehicle crashes.
It's hard for someone new to this data like myself to reconcile the differences in these results. I'm not sure in your post what a cloud thing is, but I do know that people use these tables to go tire shopping. My problem isn't the absolute numbers, it's the ~28% net gap in results between the two testing methodologies, and the specific claims that a small unsurfaced drum and a direct weight loading would read to results that didn't track with real world performance. The net 28% gap between two different test methodologies results in a real quandary for someone trying to "buy a fast tire" with a limited budget. At this point I feel like I know less than when I started.
ccand51997 I suspect you are right that trying to test this on my own is extremely hard and will probably fail. But I find that "the act of doing" often teaches us things, even if they aren't what we set out to learn. For instance I've been trying to find out how to get an accurate pressure gauge (with no luck, it appears the only externally verified gauge was Accutire and they went out of business) but in the process I found this video:
https://www.youtube.com/watch?v=VLqZjoYVaHI
The person who made that video ended up with many unexpected side results as part of "the act of doing". That video ended up teaching me how much pressure is lost when the pump is unattached, and how much variation there is in floor pump gauges. Pretty interesting, considering the results of the Silca breakpoint calculator show that "going over" your breakpoint creates more resistance than any mistake in tire choice.
My plan is to use my dual sided power pedals, which I have been able to externally validate via dual recording on a Kickr bike, to put out 400 calories over a known gravel course at a constant power and rpm profile. If I collect about six samples per tire set, I can calculate margin of error for the same setup, then look to see if there is a meaningful difference between tires. Keeping the watts and speed low should help filter out aero affects.
I think the most meaningful thing I could discover is that rolling resistance itself is so marginal as to be undetectable, which would mean we should select for other factors when picking tires.
Volsung wrote:Are you competing at a high enough level where any of these watts will cost you a podium spot?
barrows wrote:My search for the right tires ended when I found the G One RS, enough grip, reliably fast, reliably puncture resistant (only downside is expense). Now I only obsess over pressures. Off course, it is going to be much more relevant to try and get one's training to an adequate point for what one would like to achieve!
@Volsung Having thought about it, I think in general I reject the implicit premise of your question, which is that rolling efficiency only matters if you are contesting a podium. I've gotten such huge gains just out of learning about tire pressure on my existing tires - gains that I have felt on every 5000-calorie day - that I can't imagine understanding tire data to be only for the purpose of contesting podiums. If your average Saturday is 100 miles on gravel, this is going to matter in your life.
On the competition side, my biggest event every year is Cascadia super gravel ("Super G"). I try to always do "the big course", which is 8k feet of vert spread out over 60-70 miles depending on year and odometer reading. Now, how much does tire choice affect my result? Probably nothing I do is putting me on the podium, though I will (finally) be in a geezer category which means it's within the realm of the possible in the coming years. I haven't been on a podium in real life since 2005 but stranger things have happened (Zwift doesn't count). I will say that BAD tire choices have affected me at Cascadia Super G, notably my first experience with 5 flats, and my ensuing total refusal to run a certain tire brand that also makes wheels (I won't start that here).
I don't think you have to be certain you'll be on a podium to care about rolling resistance. I agree with @thumper88 above that it probably makes a big difference even for people who will never race. I could sandbag and drop down a category and be certain I would be contesting a podium at every race- if I did this would I then receive a license to care about tire data?
@thumper88 Interesting to hear that you - just like the guy in the video I cited - had a bad experience with Silca on-pump gauges. "2" isn't data, but it's a trend. I think where you & I disagree is simply in the idea that netted together, all the rolling resistance data sources agree and that if you pick a tire that tops most of the charts, you'll be ok. What I see, when I dump the data into Excel and start looking at paired testing of equivalent tires, is two completely different testing regimes that get different answers. Disagreement is the natural state when we're figuring out how bicycles work, but I want to thank you for the patient and informed way in which you disagree.
Why does any of this matter?
It's important to remember that we were racing on 120-200 psi on the road FOR YEARS because no one was doing the real world testing. We looked at drum resistance, that test said "more PSI is faster", and so everyone, including the pros, raced on high pressures that were much slower. The incredible work done to find the "break point" phenomenon, and the discoveries from the big-volume/low-PSI people (Rene Herse, Tom Anhalt, Josh Poertner) on pressure breakpoints has absolutely changed cycling. As someone who did hundreds (!!) of crits on 150+ psi and has suffered terrible crashes during those years, I like to question the thinking of the day because I've seen it change. I've been in criterium parking lots listening to racers say that 200 PSI was faster than 150 PSI. I would love to go back in time and show up with "fat" tires at 90 PSI and absolutely smoke corners from a place of grip safety.
Now we have this emerging sport of gravel racing with new ideas everywhere and very little data. We have many manufacturers of aero gravel wheels while Rene Herse is asserting publicly that above 32mm you can't get aero gains on big tires (and Enve agrees!?). We have Cannondale shipping full-suspension gravel race bikes. Which matters more, suspension or aero? Neither? And finally we have the divided church of rolling resistance, fighting about test methodologies and getting very different answers. I am invested because I've seen so much change since I first pulled up to a race line in 2002. So many times we've gone from "everyone does it" to "nobody does it". Look at an old downhill race bike with 26" tires and its steep head angle and try not to laugh! Gravel feels very early days and I expect we'll look back at this time and laugh as well. The way forward is always science.
Reminder again to all that my original question was about the impact of the changes in methodology at Wheel Energy: large drums and shock-driven leveraged sensing. I've read in this thread that BRR has been doing rolling resistance testing longer than anyone else. I have no direct knowledge, but Wheel Energy claims they've been testing since 2003:
It may seem like the early days in some ways but …. As with aero it took only a few short years for the low hanging fruit to be picked.. they may get another watt or two out of good gravel tires but at the end of the day they have to resist flats….
Road tires for example are all piling up around 7-10w at fast end, BRR measured.
Gravel tires that are actually functional? 17-21w for fastest.
at some point there aren’t any big tricks left in the magician’s hat…just tiny changes.
it almost took gravel to make RR important. In a world tour race in 1980 tires were so similar there prob wasn’t 2 watts difference between most.
but in gravel it’s been hugely helpful as a framework for thinking through why tire pressure and volume is so important on rough surfaces and what to do about those things.
and now bikes are able to handle 700c tires up to 50mm in some cases we’re starting to see the upper limits of what works well for width, at least for typical races.
and yes you can still get some aero benefit from medium to deep wheels, if you hold front tire width to a dull roar. And depending on the AWA (apparent wind angle).
specialized tested in “wintunnel””
And schwalbe gas tested though jyst for internal consumption, it has not been published. Their engineers say it’s pretty startling the difference in drag from different sizes of side bobs which of course can detach flow before it reaches the wheel.
so… in some cases I’ve downsized front a few mm and gone with rounded profile. 3-4 watts saved for 100-plus miles upwind in 20-22kts is not as small as it sounds.
thumper88 wrote:...New materials could make a big difference. Consider carbon fiber in frames. Or lithium in batteries. Of course I don't know what those materials might be, if I did I'd be selling them.at some point there aren’t any big tricks left in the magician’s hat…just tiny changes.
...
stu wrote:New materials could make a big difference. Consider carbon fiber in frames. Or lithium in batteries. Of course I don't know what those materials might be, if I did I'd be selling them.
stu wrote:New materials could make a big difference. Consider carbon fiber in frames.
ccand51997 wrote:
Carbon fiber made a big difference in aero frames, but I'm not sure they did much in other areas other than drop a couple of pounds and increase the cost considerably.
When newbies ask me about gravel bikes, I tell them to focus on tires. A set of good tires at 16 watts vs. say a Maxxis tire at 30 can make a 28 watt difference. At most, a steel to carbon frame is going to get you 3-4 watts climbing and almost nothing anywhere else.
To me, the material trend I just can't understand is carbon in non-aero wheels. They go for two or three grand and are not measurably faster than my cheap, handmade wheels I put together with some used spokes, used DT swiss hub and a sub-$100 wtb rim. I've heard people say they are much tougher, but I've never had an issue with a WTB rim unless the tire went flat on a descent and I did not realize it.
barrows wrote:
Totally disagree on carbon wheels for gravel. Consider the Roval Terra CL, for example. Very light, very stiff and responsive wheel, only ~$1500.00. 25 mm inner width, you are not going to get anything which compares to that with an aluminum rim. There is almost no aero advantage when talking about 40 mm and up tires, so there is no need to consider that. At the same size (inner width), a carbon rim is lighter, stronger, and stiffer than aluminum. carbon rims offer higher performance, and there are relatively affordable carbon wheels out there which are very good, such as what I mentioned.