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Thread: Some testing

  1. #1
    LMN
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    Some testing

    No not 29ers or expert men vs. elite women but some tire testing.

    Two sets of tires:
    Set 1: Maxxis Cross Marks UST. 20 psi. in the front, 21psi in the rear.
    Set 2: Maxxis Ignitor on the front and Aspen on the rear. Both are non-tubeless, but converted. 24 psi in the front, 25 psi in the rear.

    The non-UST wheels are 297 grams lighter.

    I used different pressures for the tires because that is how I ride them. At low pressure I have issues with non-tubeless tires. I would have liked to use the same tire, one UST, one not UST but I didn't have any non-UST Crossmarks.

    Used the exact same bike with both tires mounted on Mavic SLRs (the wheel with UST tires has an XTR casset, the one with non-UST has an XT casset). A Mtb SRM was used to measure power output. Before each test I made sure that my weight with water and gear was exactly the same (146.2 lbs). It was a calm day, wind had no effect.

    I did the test on a trail called Honey Comb. I chose Honey Comb because it has more climbing then descending (I wanted to measure climbing). Also because I built it and ride it several times a week I am very consistent on it. The trail starts off as twisty rolling single track and finishes with a about five minute switch-backing climb.

    I didn't do the test as a maximal effort, I did it at a pace that I would use for a 4hr MTb ride. I wanted the effort to be repeatable.

    Honey Comb is a smooth but twisty trail, the ideal set up allows good cornering and good acceleration. It is a smooth trail, there is no place on it where a superior ride is going to be an advantage. There is also no risk of flatting.

    My expectations for this test was that the non-UST tires would be superior. The question was how much.

    UST tires: time 9:59, average wattage 238 watts.
    Non-UST tires: time 9:50, average wattage 232 watts.

    Now I only managed to get a single run in on each tire. So the results are not worth drawing any conclusions on.

    On the second run I rode a bit better, a couple of corners I carried a bit more speed through.

    I am going to repeat the test in the next couple of days. Next time I am going to reverse the order.

    I am curious if I will see the same results, because the difference there is significant. Extrapolate that to a 2hr XC race and you are seeing a two minute difference.
    Last edited by LMN; 09-17-2009 at 08:40 PM.

  2. #2
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    Not to get off topic but can you tell me more about the Aspen. I've seen very little about it. Looks like a similar design as the Monorail, which I really like as a front tire because of its cornering.

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    I'd think you'd want to be using the same tread pattern for both tests for unambiguous power results. The Aspen has a really low and sparse tread profile.
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  4. #4
    LMN
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    Quote Originally Posted by rockyuphill
    I'd think you'd want to be using the same tread pattern for both tests for unambiguous power results. The Aspen has a really low and sparse tread profile.

    I agree. I think of this more as a tire test vs. is a heavier tire measurably slower.

    Both set of wheel do feel like roll the same. The Aspen is a bit faster then a crossmark, but the Ignitor is a bit slower.

  5. #5
    LMN
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    Quote Originally Posted by System
    Not to get off topic but can you tell me more about the Aspen. I've seen very little about it. Looks like a similar design as the Monorail, which I really like as a front tire because of its cornering.
    The Aspen is a very fast tire.

    In dry hardpack conditions it is one of the best tires I have ridden. Out side of those conditions it's performance isn't as good.

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    I have tried the 2.25" Aspen against the Conti Race King 2.2, the 2 places I noticed a huge difference: braking on loose surfaces where the Aspen doesn't have much bite; and in damp conditions (not full on wet - the sort of wet conditions maybe 4-5 hours after a rain). Definitely not a we(s)t coast tire.
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  7. #7
    ganginwood
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    just a few observations but nothing worth arguing over...
    why do a comparison on a ust to a non ust if its converted to tubeless? its essentally the same thing. why not just re-test the crossmarks with tubes in them.

    and while these tests are great entertainment to read at work, it would be hard to predict any difference (gain or loss) in a race unless its tested in a vacuum. as soon as there is a wheel to grab, the sphincter factor comes into play making all calculations null and void. by a wheel to grab i'm essentially talking about pushing yourself to follow a stronger rider. if that rider wasn't there.....the harder effort might not take place

    with that being said, i don't question the results on the measured power. but are we to assume that the 300 gram difference made the effort 2.521% easier and is contributing to the time or is it the increased tire preassure that made the effort easier?

    either way, i'd probably want the faster wheel. but thats just me
    Quote Originally Posted by Mike Aswell
    the 5th poster, ganginwoods, is correct

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    interesting. i know you have always talked how catharine runs UST and doesn't worry about the weight etc. does this make you think twice about the weight?

    one thing i would suggest is why not run both sets at the higher PSI? just to take that variable out of the equation.

    keep the info coming.

    as well, would really like to see results from the same tire in UST and non UST.

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    i think psi and rolling resistance played a greater role then weight in this test if its a faster trail. Diddo on the read while at work lol, more tests please

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    Quote Originally Posted by LMN
    No not 29ers or expert men vs. elite women but some tire testing.

    Two sets of tires:
    Set 1: Maxxis Cross Marks UST. 20 psi. in the front, 21psi in the rear.
    Set 2: Maxxis Ignitor on the front and Aspen on the rear. Both are non-tubeless, but converted. 24 psi in the front, 25 psi in the rear.

    The non-UST wheels are 297 grams lighter.

    I used different pressures for the tires because that is how I ride them. At low pressure I have issues with non-tubeless tires. I would have liked to use the same tire, one UST, one not UST but I didn't have any non-UST Crossmarks.

    Used the exact same bike with both tires mounted on Mavic SLRs (the wheel with UST tires has an XTR casset, the one with non-UST has an XT casset). A Mtb SRM was used to measure power output. Before each test I made sure that my weight with water and gear was exactly the same (146.2 lbs). It was a calm day, wind had no effect.

    I did the test on a trail called Honey Comb. I chose Honey Comb because it has more climbing then descending (I wanted to measure climbing). Also because I built it and ride it several times a week I am very consistent on it. The trail starts off as twisty rolling single track and finishes with a about five minute switch-backing climb.

    I didn't do the test as a maximal effort, I did it at a pace that I would use for a 4hr MTb ride. I wanted the effort to be repeatable.

    Honey Comb is a smooth but twisty trail, the ideal set up allows good cornering and good acceleration. It is a smooth trail, there is no place on it where a superior ride is going to be an advantage. There is also no risk of flatting.

    My expectations for this test was that the non-UST tires would be superior. The question was how much.

    UST tires: time 9:59, average wattage 238 watts.
    Non-UST tires: time 9:50, average wattage 232 watts.

    Now I only managed to get a single run in on each tire. So the results are not worth drawing any conclusions on.

    On the second run I rode a bit better, a couple of corners I carried a bit more speed through.

    I am going to repeat the test in the next couple of days. Next time I am going to reverse the order.

    I am curious if I will see the same results, because the difference there is significant. Extrapolate that to a 2hr XC race and you are seeing a two minute difference.

    I agree the results are not worth drawing any conclusions on except to say the tires did not make a measurable change...

    I would have thought that maybe the first ride was just a warm up for the second ride...

    I have been kinda testing out Crossmark 2.1 vs a Conti Vertical 2.3 on the rear..

    The results are similar except the Crossmark is much faster on pavement, and the Crossmark gets overwhelmed with mud faster than the Vertical, and the Vertical is better on gravel than the crossmark...

    So fast clay track use a Crossmark, lots of gravel and rougher use the Vertical.

  11. #11
    LMN
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    Quote Originally Posted by ganginwood
    just a few observations but nothing worth arguing over...
    why do a comparison on a ust to a non ust if its converted to tubeless? its essentally the same thing. why not just re-test the crossmarks with tubes in them.
    They aren't the same thing though.

    UST tires have much thicker side walls. This makes them heavier, but safer against flats and more comfortable at low pressures. Converted tires are light, but more vulnerable to flats and "burps". Also at pressure around 20psi I tend collapse the side walls under hard cornering.

    I am running different psi because I want to test the tires set-up optimally. UST tires allow me to run lower air pressures, which is an advantage of them. By running the same pressure I would be isolating the disadvantage of UST tires (the weight).



    with that being said, i don't question the results on the measured power. but are we to assume that the 300 gram difference made the effort 2.521% easier and is contributing to the time or is it the increased tire preassure that made the effort easier?

    either way, i'd probably want the faster wheel. but thats just me
    I am not sure what caused the difference. As I said I felt I rode better in the second run, that alone could explain the gap. I don't think it is the increased air pressure that made the other tires faster, I noticed right away a decrease in the quality of the ride of the bike with the increased pressures. I would expect that if I ran the UST tires at that pressure they would be at a greater disadvantage.

    I am looking forward to retesting. Honestly I didn't expect there to be a measurable difference between the two wheel set-ups.

  12. #12
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    Quote Originally Posted by kevbikemad
    interesting. i know you have always talked how catharine runs UST and doesn't worry about the weight etc. does this make you think twice about the weight?
    Definately.

    One of the driving reason why am doing the testing is so she as much information as possible when making her tire choices.

    I also want to test the effect of rolling resistance. I don't believe that for MTBing that rolling resistance is that significant (speed are too low). I am going to compare a set of Maxxis Medusas to the Aspen Ignitor set-up. I expect the Medusas to be slower but not significantly slower.

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    Quote Originally Posted by north_of_us
    i think psi and rolling resistance played a greater role then weight in this test if its a faster trail. Diddo on the read while at work lol, more tests please
    The trail is fairly slow. 2.1kms in 10 minutes (12.6km/hr).

    I am temped to do a roll out test and see in there is a significant difference in rolling resistance. On flat pavement both sets of tires feel like roll about the same.

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    Quote Originally Posted by LMN
    Definately.

    One of the driving reason why am doing the testing is so she as much information as possible when making her tire choices.

    I also want to test the effect of rolling resistance. I don't believe that for MTBing that rolling resistance is that significant (speed are too low). I am going to compare a set of Maxxis Medusas to the Aspen Ignitor set-up. I expect the Medusas to be slower but not significantly slower.
    i know, we worry about rolling resistance so much, but at any significant speed, wind resistance is probably what causes way more resistance.

    i have tried UST tires, they felt really sluggish to me, but I can't even recall the tires and it wasn't even on my bike. i know that the Schwalbe Racing Ralphs 2.25 with Snake Skin are probably the closest tires I have to a UST casing and weight and they are SLOW, very sluggish feeling, OK traction, but I am much faster on others. not sure if it is the snake skin casing, cause others seem to think those tires are fast rolling, but they aren't for me.

    anyway, keep the tests coming.

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    nice

    having average power and time with a correlation (higher average power and longer time to finish) in the first test is pretty telling. will be interesting if that relationship holds in the follow on.

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    Quote Originally Posted by LMN
    I don't believe that for MTBing that rolling resistance is that significant (speed are too low).
    I dunno, a 2.1" Stick-E Nevegal feels like rolling through molasses compared to the Race King 2.2 SS. At any speed it feels like having a disc brake dragging by comparison.
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    Pauly
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    This bogus testing is getting way out of hand!

    LMN: While I have great respect for your mtb knowledge and straight talk, you really need to read up on hypothesis testing. It's covered in every introductory statistics course. The randomness in your test is probably much more than the true difference between tires. Actually we can't tell without much more data.

    How much of the variation in the data is random? That is, how do you know that you wouldn't get the opposite result if you went out and did the same test again? What if you did the test 10 more times and got the same result 8 times and the opposite result twice?

    Comparing averages between two large groups of riders, each taking multiple runs and blind to which tire they are using would "regress out" many of the problems with this test. Then you can use the date and apply the basic tools of hypothesis testing.

    Sadly, nobody company would fund a test like this - it would cost thousands of $$. And how valuable would the information be? The money would probably be more wisely spent on some advertising or by paying some fast guys to say that their tires are the best.

    It's OK LMN You are still my fav. source for info on mtb racing.

  18. #18
    LMN
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    Quote Originally Posted by Pauly F
    LMN: While I have great respect for your mtb knowledge and straight talk, you really need to read up on hypothesis testing. It's covered in every introductory statistics course. The randomness in your test is probably much more than the true difference between tires. Actually we can't tell without much more data.

    How much of the variation in the data is random? That is, how do you know that you wouldn't get the opposite result if you went out and did the same test again? What if you did the test 10 more times and got the same result 8 times and the opposite result twice?

    Comparing averages between two large groups of riders, each taking multiple runs and blind to which tire they are using would "regress out" many of the problems with this test. Then you can use the date and apply the basic tools of hypothesis testing.

    Sadly, nobody company would fund a test like this - it would cost thousands of $$. And how valuable would the information be? The money would probably be more wisely spent on some advertising or by paying some fast guys to say that their tires are the best.

    It's OK LMN You are still my fav. source for info on mtb racing.
    I absolutely agree with you. The test results do not mean anything. It is a single test on a single day. To be able to say difference is statistically significant I would have to do many test, with as you pointed out many different riders. I have a degree in mathematics; I know just how flawed my test is.

    You have nice summed up as to why there is not a single test of any value to show what is faster dually or hardtail, 29er or 26er, ect.....

    All that being said, collecting data is a starting point. Combine enough data with some "feel" and I get an indication as to what is quicker on a particular trail for myself. Another rider with a different style and different skill may not get the same results.

  19. #19
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    Quote Originally Posted by rockyuphill
    I dunno, a 2.1" Stick-E Nevegal feels like rolling through molasses compared to the Race King 2.2 SS. At any speed it feels like having a disc brake dragging by comparison.
    Funny you say that. I have a 2.1 Stick-E Nevegal on my dually right now. On the road I hate it. But as soon as I hit the dirt I don't find it too bad (although I love how hard I corner with it on).

  20. #20
    LMN
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    Did the test again tonight.

    Tonight I went harder. I rode at my 2hr race pace, not full out, but a maintable effort.

    On the first run I used the Ignitor/Aspen, second run the UST CrossMarks. On both runs I rode very well. I definitely prefer the CrossMarks in the corners and found that on the steep part of climb they offered more grip.

    Ignitor/Aspen time: 9:06 average watts 270 (1st run)
    CrossMarks time: 9:06 average watts 274 (2nd run)

    The conditions did change a bit between tests, on the first run I had a bit of a head wind up the climb, it was calm for the second run.

    I am quite impressed that I managed to do the same time for both runs.

    This is interesting to me. I am a huge fan of UST tires. I do not like where this is going. Definitely more runs are in order.
    Last edited by LMN; 09-18-2009 at 08:16 PM.

  21. #21
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    You'd like the RK's then, all the wet root and rock grip with none of the weight or sloooooowness of the Stick-E Nevies. And they stick like magic on sand and pea gravel or dust over hardpack.
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    Is it just me or is anyone else jealous that LMN has an SRM and enough wheels, tires and bikes to play around with things like this?

    It seems like a lot of fun to me.

    Keep the non-statistically sound tests coming. With enough pseudo-replication, you'll get it past 95% of people. For the rest, you can boot-strap your samples and use a Bonferroni correction.
    Canuck in the homeland

  23. #23
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    Quote Originally Posted by transient
    Is it just me or is anyone else jealous that LMN has an SRM and enough wheels, tires and bikes to play around with things like this?

    It seems like a lot of fun to me.

    Keep the non-statistically sound tests coming. With enough pseudo-replication, you'll get it past 95% of people. For the rest, you can boot-strap your samples and use a Bonferroni correction.
    You should see the bike I am doing the testing on; there is only two of them in existence.

    Actually the quiver is rather empty right now. With everyone away racing and bikes all over the continent, there is maybe a dozen bikes in the house right now.

  24. #24
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    tires are silly things.... we put so much weight on them (figuratively and literally).

    lets get rid of them altogether. i think they are just holding us all back.

  25. #25
    LMN
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    I just broke down the runs in the last test.

    On the first half the course I averaged the exact same power output for both runs (245.8 watts) but was 4 seconds faster on the first run.

    On the second half the course (the climb) on the first run I averaged 298.4 watts for 4:00 minutes. For the second run I averaged 309.5 watts for 3:56.

    Yes, I admit it, I am a geek.

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