Jan Heine "Busts" Another Tire/Wheel Myth...
 

A few years ago Jan Heine dispelled the generally held belief that narrower tires are always faster than wider tires of the same size. There are some particular and specific parameters, but it really shook up the industry. (https://www.renehersecycles.com/12-m...es-are-slower/)

Well, last week he challenged the notion that 700 wheels roll appreciably faster than 650/26" wheels (and smaller). Again, there are specific parameters (the wheels must have pneumatic tires on them).

https://www.renehersecycles.com/why-...t-roll-faster/

As before, how a tire/wheel combination FEELS can be different from how it PERFORMS.

I like his Bon Jon Pass tires, but Jan Heine and the scientific method have only a passing acquaintance. I would take his conclusions with a large grain of salt.

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.

Heine's been saying this stuff for decades. He also believes that bottom bracket stiffness is self-defeating etc. Interesting fellow, I'm not sure what to think about his ideas. I do like his tires, though.

I read that article, and it seems a bit thin and overly specific to me.

What really caught my attention is that he used off-road vehicles to make his point, but if you look at off-road BIKES, it has become apparent that 29” wheels roll faster, which is why they have dominated XC racing for years, are the majority in Enduro, and are making big inroads in DH.

The downsides of larger wheels off road has been about handling and design constraints.... the issue of whether they roll faster has been pretty well settled.

Every so often when I read one of Heine's articles I'm reminded of the excellent Wikipedia article on chauvinism (see https://en.wikipedia.org/wiki/Chauvinism), especially the second and third paragraphs. Fanatical devotion and undue partiality to the cause of Rene Herse building the best possible bicycles ever, anyone?

Of course, that partisanship doesn't mean he won't follow the market. Why else would Rene Herse offer twice as many tire models in 622 than they do in 584?

Did someone recently revoke his Ph.D.?

His joint article on relation of Q-value to efficiency in BQ demonstrated the issue. They took old measurement data, from a thesis (?), that, within errors, showed no significant correlation between Q-value and efficiency. The data were apparently never published as contributing next to nothing to the question. However, the average values seemed to line up with the claim that a low Q value helps up to a point. A lay person tends to disregard the errors and they wrote an article for BQ few pages long making the claim of evidence. Well, these data still contributed next to nothing to the question, just a hint that maybe more measurements are desired.

Having a PhD doesn't get anyone a free pass.

You might wish he could move on from this and prove something else but I guess that wouldn't sell tires

To be fair, testing tires under real-world conditions is an exceedingly complex undertaking in controlling for all the possible variables, including subjective ones, and he does point this out in his articles. I believe Heine has done as good a job at this as anyone has attempted.

N.B. I also seem to recall that Heine has an advanced degree (post-graduate, not sure if MS or PhD) in geology, so he likely has a decent grasp of the scientific method.

If only there was a website that independently tested tires and had a pretty good size database of them with CRR/wattage data at different pressures? Hmmm.

I have considered this question over the years, as I like the 26" platform but, in real world application, do find 700c to roll faster. If only it weren't so.
What I think is that it goes beyond tire size to construction considerations.

Until recently, it was hard to get a 26" size tire designed for speed. Most come out of the off road or touring genre where durability is prioritized over speed. The same goes for wheelsets. Again, until recently, most 26" wheels were build for toughness rather than speed while 700c has a longer history (and trickle down effect) related to racing like lower spoke counts, aero design, light weight materials etc... And, lastly the gearing/geometry of 26" bikes usually hasn't been optimized for speed (unlike many 700c road bikes).

Add all those factors up and 700c has been historically faster than 26".

I'd like to see two similar bikes, using similarly designed wheelsets, with 26" and 700c tires go toe to toe. A part of me would be cheering for the underdog :)

My take away is that he thinks that little energy is actually dissipated by frame and BB flex (energy is just stored briefly) and so you need to consider the dynamics of a rider’s pedal stroke and a bike’s frame flex throughout the pedaling cycle and find an optimal match.

Thus, stiffness should match the rider’s power output, with stronger riders needing stiffer frames while lower output riders will prefer to ride more flexible frames.

It’s an interesting idea. The first part doesn’t surprise me and could be verified with appropriate testing. The second part is probably much more subjective, though I suspect stronger riders will generally tend to like stiffer frames.

Otto

You have assembled all of the pieces - now put them together. With Heine's background, he should understand that he lacks the resources to control for "all the possible variables" and hence his results are dubious.

Just chatting nothing technical to add.

I just started doing club/group rides, I have 6 or 7 rides in which are the first group rides (outside of two organized mass rides) since the mid 1990s. My current bike is nothing special, actually one of the few non-carbon frames in the groups I ride with. Although nothing special, it is a huge improvement over what I had in the mid 1980s to 1990s. 9 speed, AL frame, 700 x 23 tires.

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. Anyway, although I consider myself a newb and thus fitting the mold of only newbs using skinny high pressure tires, I'm not having any problems keeping up with my fellow riders. This is in a hilly area, not big hills, maybe 1600 feet of ascent over 22 miles but not flat by any means. Maybe this says more about them than me, I don't know.

I don't think anyone, even Heine, has claimed that wider tires are faster than narrower tires; only that they are more comfortable and not slower (or at least, not that much slower.)

I’ve accidentally had some practice at this. I regularly ride both of my bikes, an 80s MTB and and 80s road bike and there is a significant overlap of routes I ride with both.

Until the pandemic, both had the same fit, with classic round drop bars and 11.5 cm from saddle top to stem clamp center. I also had “road” tires on both though most riding is on crushed stone and concrete paths. So 700x32 Ultra Sports and 559x58 RTPs.

Both bikes are steel frame and heavy by modern standards: the road bike is about 27 lbs and the MTB about 29 lbs.

On a favorite flat route with only hills when first heading out and finally getting home, the 26er was about as fast and more comfy. Terrain matters as I cross old railway bridges and I can hit hit them faster with the bigger tires. Best route times and level speeds were about the same.

On hillier routes, the 700c bike was consistently about 1 mph faster overall, which I assume is partly the weight on the climbs and partly because those routes tend to be more pavement where the damping of the 26” tires isn’t much of an advantage.

Since the pandemic I’ve changed both cockpits (raised the bars on the road bike and swapped for Scott AT-4 Pro on the MTB) so that part is less comparable but the results are pretty much still the same.

Otto

Oh. Thank goodness!

The riding surface will decide what tires are faster. Racers use wider tires on rougher surfaces (rough roads and gravel) and of course they are optimizing for actual riding speed.

Otto

Earning a PhD implies that you (under the guidance of a mentor) have shown expertise in the very specific field/topic in which you did research. Along with the topical knowledge of that very specific field is an understanding of the accepted scientific research models and types of data/experiments/observations and expectations of that field, and also the accepted methods of analyzing that information (again, in that field).

Having a PhD in geology makes one an expert in bicycle tire research about as much as earning MD in orthopedics makes one able to diagnose heart problems. Sure, they will likely understand better than the average Joe, but it is not their area of expertise.

Further, getting a PhD is just the first step. It is what you do AFTER that which determines if you are an expert in your field. Or have much credibility as a scientist at all.

Well said.

For example, this person has a PhD in my field - and from Harvard, which is a top program. But he is widely regarded (rightly so) as a joke. He literally made up sources for some of his books.

...combining his education and his business....he clearly knows how to ride a bike over rocks....using his own tires.

https://www.renehersecycles.com/wp-c...rner.jpg?w=640

Yet the fact that there are Bon Jon Pass tires for you to like is arguably due to his methods that you disparage.

"The scientific method" is often put on a pedestal and dressed in a lab coat, leading to confidently repeating steel drum tests that show 19mm tires at 120psi to be best.

The scientific method doesn't generally tell us what is "best."