Jan Heine "Busts" Another Tire/Wheel Myth...
#26
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#27
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The move away from those narrow tires started way-before Heine was involved. 21 mm tires are, themselves, "really old".
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Anyway, on a recent group ride we were on a rest stop and the conversation turned to wheels and tire size. 32s seem to be the normal. One of the riders made the comment that implied that only newbs or holdovers from 80s ride with 23 or 25s. I of course have 23s and I sensed this person realized this only after making the statement. No bother to me, I'm not going to throw a bunch of dollars at my bike to make others happy. I have a 700 x 28 tire that was given to me, it fits but is tight.
In reality it is about the legs than anything else. A strong rider will always beat a weak rider no matter what tire is used.
John
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The "ideal" stiffness, in different situations, might not be the same for a particular rider either (more stiffness might be better for climbing and less better for "cruising"). A "more comfortable" frame might be faster for longer rides.
I don't think it matters as much as some think. Being able to claim a frame is "stiff" makes it easier to sell.
#30
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True. Not promoting Jan Heine ('tho I have received a sub to bicycle Quarterly as a gift and generally enjoy it),
so much as pointing to the issue of quasi-religious devotion to "the scientific method".
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It is funny but at one time only newbs on cheap bikes and old people rode 32’s. I’ve gone from 20mm to 25mm over the years. Pretty sure I can’t fit 28’s on my road bike. I’ll stick with 25’s. I’m not about to change bikes for a wider tire.
In reality it is about the legs than anything else. A strong rider will always beat a weak rider no matter what tire is used.
John
In reality it is about the legs than anything else. A strong rider will always beat a weak rider no matter what tire is used.
John
#32
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The idea that "narrow tires with lots of pressure" is still fairly common and it doesn't appear to be true for the kinds of riding people are generally doing.
Heine is useful because he's calling into question things that many people just assumed to be true (without much support).
It's hard to design experiments that reveal what is going on with tires. Heine is, at least, making some sort of somewhat-reasonable attempt at it.
The argument that he can't do good work in this field "because his PhD is in geology" doesn't make much sense.
Last edited by njkayaker; 07-23-20 at 11:45 AM.
#33
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Not that I doubt the accuracy of his findings (within such a limited scope-- Heine's "science" is on par with say Mythbusters or GCN Does Science) but I think that it's natural for readers to raise an eyebrow when they read through "tire test performed by the guy who sells tires." Impartiality tends to stop just before it reaches the bottom line.
#34
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Wheels on racing vehicles are as small as possible because rotating mass (and unsprung weight) is a huge issue. Racing vehicles will nonetheless run very big wheels at times, because they need to fit very big brakes-- not an issue with bicycles. Bikes are fairly limited as to what their tire height can be relative to width-- cars do not have this limitation, because they can run a tire with 5 plies in the 6" high sidewall.
I agree with everything stated about hysteresis, but there is obviously a practical limit-- if there wasn't, we'd all run motorcycle-sized tires... and there's Fatbikes, which do pretty much that, but are inarguably niche bikes with a narrow range of applications. This is (IMO) why their test seems to completely ignore the flywheel effect-- if they had tested a solid aluminum 20" wheel with any BMX tire on it, it would roll farther than all of them. End of the day, once fitted with an appropriate tire, 700c, 650b, and 26" all stand roughly the same height-- so it's not surprising that they would all roll similar distances. Somewhere in there is a point of diminishing returns.
I agree with everything stated about hysteresis, but there is obviously a practical limit-- if there wasn't, we'd all run motorcycle-sized tires... and there's Fatbikes, which do pretty much that, but are inarguably niche bikes with a narrow range of applications. This is (IMO) why their test seems to completely ignore the flywheel effect-- if they had tested a solid aluminum 20" wheel with any BMX tire on it, it would roll farther than all of them. End of the day, once fitted with an appropriate tire, 700c, 650b, and 26" all stand roughly the same height-- so it's not surprising that they would all roll similar distances. Somewhere in there is a point of diminishing returns.
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I like the part where he points out the wheel size on the vehicle with two feet of suspension travel
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Otto
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https://blog.silca.cc/asymmetric-eff...e-optimization
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Drum testing (like bicyclerollingresistance.com does) doesn't always reflect real world performance.
https://blog.silca.cc/asymmetric-eff...e-optimization
https://blog.silca.cc/asymmetric-eff...e-optimization
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In the heyday of bicycles (when the really bright people were designing bikes, not computers, software, aerospace ... someone did a study of wheel diameter vs road surface. (This was back when the worst roads were, by our standards, really bad and good pavement was a new concept.) He found that the rougher the surface, the bigger the optimum wheel diameter. Interestingly, he found that on smooth pavement, 27" was optimum. (27" being nearly exactly the outside diameter of a 700c road tire.)
Racers have settled on that diameter. Now, there have been race bikes built around much smaller wheels. In criteriums those bikes are fully competitive because what they give away in rolling resistance they gain in radically lower inertia; paying real dividends every corner.
The place where we moderns missed the boat is on poor surfaces. Mountain bikes. 45 years ago, the 26" wheel was adopted. Not because it had any advantages but because kid's bikes were available and cheap. Yes smaller wheels do better in tight places and fit smaller people better, but the disadvantages on rough surfaces were so limiting that you had to be seriously hard core (and slightly crazy) or willing to spend money, research, technology, etc, etc, to get enough suspension to make those bikes rideable. Much later, the 29s came along. Just what that guy told us 120 years ago!
Ben
Racers have settled on that diameter. Now, there have been race bikes built around much smaller wheels. In criteriums those bikes are fully competitive because what they give away in rolling resistance they gain in radically lower inertia; paying real dividends every corner.
The place where we moderns missed the boat is on poor surfaces. Mountain bikes. 45 years ago, the 26" wheel was adopted. Not because it had any advantages but because kid's bikes were available and cheap. Yes smaller wheels do better in tight places and fit smaller people better, but the disadvantages on rough surfaces were so limiting that you had to be seriously hard core (and slightly crazy) or willing to spend money, research, technology, etc, etc, to get enough suspension to make those bikes rideable. Much later, the 29s came along. Just what that guy told us 120 years ago!
Ben
Last edited by 79pmooney; 07-23-20 at 09:19 PM. Reason: SIgnificant typo, 1st paragraph
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#42
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No, but a Ph.D. in a field of science from the University of Washington makes me more willing to take him seriously than an anonymous person on the internet who makes such claims. As a scientist myself, I have a reasonably nuanced idea of what constitutes "scientific method," and from everything I have read from Jan Heine, it is clear he does as well.
It is cheap and easy to denounce someone like this on the internet, but I would find evidence far more compelling.
It is cheap and easy to denounce someone like this on the internet, but I would find evidence far more compelling.
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#43
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#44
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The scientific method is for testing hypotheses, which might include questions about the effect of tire size (or width) on rolling resistance, smoothness/comfort, speed, etc. But since those are sometimes competing goals, it cannot tell us what is "best." In other words, "best" is a subjective judgment which reflects preferences or priorities.
#45
In the heyday of bicycles (when the really bright people were designing bikes, not computers, software, aerospace ... someone did a study of wheel diameter vs road surface. (This was back when the worst roads were, by our standards, really bad and good pavement was a new concept.) He found that the rougher the surface, the bigger the optimum wheel diameter. Interestingly, he found that on smooth pavement, 29" was optimum. (27" being nearly exactly the outside diameter of a 700c road tire.)
Otto
#46
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In the case of Heine's experiments, I've always found that - while he may be doing as well as possible for "real world" tests - his methods don't allow him to adequately control for the variables other than those in which he is interested. (You know, the whole ceteris paribus thing.) Additionally (and this is not entirely disqualifying, but still), it is clear that he is a less-than-dispassionate analyst.
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The "scientific method" is an overly idealized conception of what happens when people "do science".
It doesn't capture the "try stuff out (in a reasonably careful/disciplined way) and see what people think of it".
???
The point is to understand the properties so that it can inform a choice.
No one is saying the purpose is to determine a singular "best" tire for all uses.
It seems that a wider tire is objectively better than a narrow one for rough surfaces (that is, it doesn't seem to be merely a "preference").
Seems like a normal thing for these sorts of investigations (looking at a complex situation with a limited budget). In any case, it might be better than nothing (it doesn't seem what was done before was better).
The alternative was hewing to the standard "understanding" of narrow/high-pressure being faster (based on assumptions and worse investigations).
It appears, he's managed to challenge many assumptions reasonably convincingly, Maybe, not perfectly (but, so what?).
It doesn't capture the "try stuff out (in a reasonably careful/disciplined way) and see what people think of it".
The scientific method is for testing hypotheses, which might include questions about the effect of tire size (or width) on rolling resistance, smoothness/comfort, speed, etc. But since those are sometimes competing goals, it cannot tell us what is "best." In other words, "best" is a subjective judgment which reflects preferences or priorities.
The point is to understand the properties so that it can inform a choice.
No one is saying the purpose is to determine a singular "best" tire for all uses.
It seems that a wider tire is objectively better than a narrow one for rough surfaces (that is, it doesn't seem to be merely a "preference").
It appears, he's managed to challenge many assumptions reasonably convincingly, Maybe, not perfectly (but, so what?).
Last edited by njkayaker; 07-23-20 at 02:59 PM.
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#49
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???
1) The point is to understand the properties so that it can inform a choice.
No one is saying the purpose is to determine a singular "best" tire for all uses.
2) It seems that a wider tire is objectively better than a narrow one for rough surfaces (that is, it doesn't seem to be merely a "preference").
3) Seems like a normal thing for these sorts of investigations (looking at a complex situation with a limited budget). In any case, it might be better than nothing (it doesn't seem what was done before was better).
The alternative was hewing to the standard "understanding" of narrow/high-pressure being faster (based on assumptions and worse investigations).
1) The point is to understand the properties so that it can inform a choice.
No one is saying the purpose is to determine a singular "best" tire for all uses.
2) It seems that a wider tire is objectively better than a narrow one for rough surfaces (that is, it doesn't seem to be merely a "preference").
3) Seems like a normal thing for these sorts of investigations (looking at a complex situation with a limited budget). In any case, it might be better than nothing (it doesn't seem what was done before was better).
The alternative was hewing to the standard "understanding" of narrow/high-pressure being faster (based on assumptions and worse investigations).
2) Scientific testing might prove that a wider tire gives a smoother ride, but only you (your preferences) can determine whether that is "better," since a wider tire brings other tradeoffs. This gets to your first point: that the tests can only inform your choice, not determine what is "best" in any universal sense.
3) Agreed.
#50
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