Myths In Cycling

82 replies · 1,776 views

ljsmith
762 posts
#1Jan 23, 2021, 1:15 PM
Rene Hearse (Jan Heine) has a list of "Myths in Cycling" which is a great read. Most are tire and wheel related. Keep an open mind when reading these, most are considered proven facts so many may find these hard to accept.

https://www.renehersecycles.com/category/myths-in-cycling/
3
Jumbo
123 posts
#2Jan 23, 2021, 1:57 PM
This ought to be a fun thread!
3
Volsung
878 posts
#3Jan 24, 2021, 10:58 AM
Jan's rather delusional.
2
stu
646 posts
#4Jan 24, 2021, 1:26 PMedited▲ Top
To the best of my knowledge Jan has a great deal of experience as well as the talent and resources to put his ideas to the test. I also find his arguments logical and easy to follow. However I don't agree with all of his conclusions, usually due to different personal preferences but in a few instances due to what I consider incomplete data. A few examples:

Jan likes a flexible fork. Jan likes a light bike. Jan can afford the very best, even if he has to design something new and have it built. Rim brakes are light and work well with flexible forks so they're great for Jan. I'm not that concerned about weight and I want powerful brakes and the ability to swap wheels at a reasonable cost so discs work better for me. If I needed more fork flex I'd consider a Lauf Grit fork.

Jan says with supple tires rim width doesn't matter, at least between ETRTO minimum (about 33%) and 80% of tire width. I personally noticed stability problems with a supple 48 mm tire on a 21 mm rim (44%) but not on a 30 mm rim (63%). On Jan's journal I suggested he test his 55 mm Antelope Hill tire on 4 different rims: 19 mm (ETRTO minimum), 23 mm (gravel), 30 mm (MTB), and 40 mm (MTB plus). I got no reply. I don't know why but my guess is he's not too interested in wide rims since they don't work with most rim brakes.

Jan also says with supple tires rolling resistance doesn't depend on pressure. He tested supple 32 mm tires on smooth asphalt at pressures of 7, 8, 10, and 13 bar. Yes, those are 102, 116, 145, and 189 psi! I asked Jan about those numbers and he confirmed they were correct. If I were doing that test I'd include lower (and what I consider more realistic) pressures of 3, 4, and 5 bar (44, 58, and 73 psi). I'm not surprised that BRR (which has its own issues) finds rolling resistance is rather strongly related to pressure.

Despite these and a few other quibbles I find Jan's writing informative, helpful, and sometimes inspiring. I agree with most of his conclusions, where I don't I usually learn something. I just read it, like everything else, with a critical eye.
6
Volsung
878 posts
#5Jan 25, 2021, 7:25 AM
Most of my issue with him is hes more focused on sales and retrogrouching than actual science, which is fine but he tries to present it in a scientific way.

My mild OCD can't handle a laterally flexy steel frame. The sound of rotors rubbing on the pads is like fingernails on a chalkboard. He can go on and on about a steel frame that doesn't meet UCI requirements, hasn't been safety tested, and has QR dropouts, but that sounds like torture. Anyone can make a dangerously light bike. Its hard to make a light good bike.

Also he blocked me on Instagram because I asked about his tires blowing off rims. Rather than answer the question he chose to hide the problem.
2
ccand51997
265 posts
#6Jan 25, 2021, 11:43 AM
I like how he challenges some long held myths and he does use a lot of logic and some testing methods, but you could drive a truck through the holes in some of his arguments. Some don't really matter to me, but I'll comment on these.
Comfort: upright vs lower
He makes a good argument here but then talks about how you need a bunch of positions to deal with changing road and atmospheric conditions. Is anyone arguing that? That is why a drop bar is superior IMO to a flat bar. It offers a lot of positions. My gravel machine has an aerobar which offers even more positions.

Tubeless tires roll faster
Anyone who does the research knows this is not so. A tubed tire with latex can be as fast as a tubeless to within a very small wattage difference. I don't ride tubeless to be faster but so I can roll them at low pressure. I love riding my GP5000s at 35 psi. Yes, 35. And my other tires at 20 to 25.

Disc vs Rim brakes
A friend of mine contemplating his first bike in 25 yeas told me he had not ever in all his years needed more braking power than he had with rim brakes. True enough. But if I want to use very wide tires then I'm using discs. I've fought with cantis and vbrakes and the fight is not worth it to me.

Marginal gains
This was his worst argument, of those I read, because he never makes a point. Marginal gains is often maligned because people don't understand how wind resistence works against you. If you do 10 things that all gain you 3 watts then you will be more efficient but the power required to overcome wind resistence is exponential and thus, the faster you go, the less those marginal gains make you faster. Those 30 watts will be very helpful at 15 mph and much less so at 26.

Tire pressure
I read bicyclerolling resistence pretty regularly, but you have to recognize the limiations of his testing. He started his site comparing tires at 120 psi, which is largely useless to me. I've never running a tire over 100 again and that is my tri bike tire that is 20mm wide to fit the deep wheel I am not going to replace. I go as low as 60 on my tubed road tires when I dare and super low on my tubeless tires.
I've done a lot of my own tire testing and never found tire pressure to make much difference when testing on the road. I run a Conti RaceKing on my gravel/all-road bike and have twice tested it at varying pressures with no discernible difference in speed. I was pretty shocked when there was no difference between 50 and 8 psi. Now I'm not going to ride at 8, but it was not any slower. I'm sure that different tires react differently in varying conditions, but I don't worry about pressure much anymore.

He also obsesses with weight overmuch, which to me is the biggest myth that should be busted. The dfference in weight is not zero but its not very important either when you consider tires, aerodynamics, suspension and other factors.
stu
646 posts
#7Jan 25, 2021, 12:46 PM
ccand51997 wrote:He also obsesses with weight overmuch, which to me is the biggest myth that should be busted. The dfference in weight is not zero but its not very important either when you consider tires, aerodynamics, suspension and other factors.

Exactly! To me weight matters when carrying a bike up a flight of stairs or lifting it onto a roof rack.

Riding up a steep hill the power required goes up linearly with total weight of bike + rider + gear. In my case that's just under 200 lbs so a full pound would change things only half a percent. Helpful if you're racing, unnoticeable otherwise.

Riding on level ground the difference in total weight affects only rolling resistance, which at any speed you're working hard enough to care is much lower than air resistance.

An aside (which Jan gets right): weight on the rim or tire as opposed to weight anywhere else only matters for acceleration. Weight right at the wheel radius has exactly twice the effect of weight which is not rotating. Not a big deal unless you're racing on an indoor track.

All that said, weight really does count if you're trying to impress an unsophisticated observer.
0
ccand51997
265 posts
#8Jan 25, 2021, 2:05 PM
[QUOTE username=stu userid=7554320

An aside (which Jan gets right): weight on the rim or tire as opposed to weight anywhere else only matters for acceleration. Weight right at the wheel radius has exactly twice the effect of weight which is not rotating. Not a big deal unless you're racing on an indoor track.

All that said, weight really does count if you're trying to impress an unsophisticated observer.[/QUOTE]

That is funny! A buddy of mine once joked that he cares about weight so he could impress his buddies before or after the group ride. And he hated climbing!
And rotating weight matters even less than you indicate. Kraig Willet (a smart engineer/cyclist) did the math and found that even half a pound on each wheel at the rim mattered less than an entire watt for performance. Even in a criterium it was like .3 of a watt.
0
Jumbo
123 posts
#9Jan 26, 2021, 8:06 PM
It's been very interesting to browse through his posts. A few things jump out at me. One is the near-constant claim that comfort=speed. I was particularly struck by his anecdote about riding with aero bars actually taking the same amount of time in a long-distance event because he was sore and had to stop more often (that said, maybe more practice on said bars would mitigate that issue). Comfort has a point at which it's counterproductive as well. The most comfortable bike I have is my 70s Schwinn tandem cruiser. I could sit on that thing all day. It's like a barcalounger. But it tops out at like 12mph. Adding a little discomfort can add lots and lots and lots of speed.

It's also a little suspicious that the research and data he gives to support his points coincidentally emphasize the products that Rene Herse sells. As always, one has to consider biases in sources, whether data is generated in blind trials, etc. Now, it could be that they sell what they sell because of their data. But it could also be that they get the data because of what they're looking for. Or, even more complicated, they looked for something, found it, and developed some products around that, which led them to look for more confirming data.

Re: weights. Sure they're not everything. That's been discussed a lot, as far as I've read. But I can tell you anecdotally that switching from a bike that's 23 lbs (two years ago) to one that's around 19 has made a world of difference for me climbing. It's really night and day.

2
chas
1,305 posts
#10Jan 27, 2021, 4:59 PMedited
stu wrote:To the best of my knowledge Jan has a great deal of experience as well as the talent and resources to put his ideas to the test. I also find his arguments logical and easy to follow. However I don't agree with all of his conclusions, usually due to different personal preferences but in a few instances due to what I consider incomplete data. A few examples...

Agreed. I'll throw in my 2cents

I love his thought process, experience, and dedication. But I find that his conclusions fit his type of riding specifically, and may or may not apply to me.

Examples:
Flexible frames are fast. Jan agreed with my "counter argument" on this, so kudos to him. My most extreme example is riding a velodrome, when I switched from a flexy steel frame to an ultra stiff modern track frame. It literally gave me the same improvement as going from 16t to 15t cog. It was that large. My argument was that if I'm randoneering at ~200watts, sure, I don't need a stiff frame and after 8 hours a compliant frame may leave me with more energy. But if I'm putting down 1000++ watts in a sprint, stiffness is everything. So yes, he is right in a specific use case, but agrees that if you want good acceleration - a stiff frame is better.

You don't need tread on gravel. While I am happy to mountain bike race on semi-slicks (in the dry), there is one huge difference with treaded and non treaded tires on gravel. Slick tires have very sharp and nasty breakaway characteristics. If its wet (non paved), they can give away as fast as a tire hitting an ice patch. When riding a treaded tire, I can drift the bike on dirt, or catch a slide. With a slick - when it lets go, it lets go very fast. So, I agree - the ultimate traction may be similar or the same, but the handling is very different. Its the difference between catching a slide, or crashing.

Either way, his posts are thought provoking - just realize its from a certain perspective.
3
chas
1,305 posts
#11Jan 27, 2021, 5:24 PM
ccand51997 wrote:

Disc vs Rim brakes
A friend of mine contemplating his first bike in 25 yeas told me he had not ever in all his years needed more braking power than he had with rim brakes. True enough. But if I want to use very wide tires then I'm using discs. I've fought with cantis and vbrakes and the fight is not worth it to me.

So true - that and having to adjust my brakes every time I had a wheel of different widths. That alone has revolutionized tires wheel options for our bikes.

He is right on the surface about "power." But the modulation with hydraulic disks is amazing braking power - more for modulation which is amazing. Good brakes of any type should be able to have the power to lock up a wheel, but of course - threshold braking is where it really makes a difference.

(theoretically you could do that with hydraulic rim brakes too, but good luck putting that together).
0
ccand51997
265 posts
#12Jan 27, 2021, 9:26 PM
chas wrote:

You don't need tread on gravel. So, I agree - the ultimate traction may be similar or the same, but the handling is very different. Its the difference between catching a slide, or crashing.

Either way, his posts are thought provoking - just realize its from a certain perspective.

I've spent a lot of time using a G-One Speed 2.0 tire over the last couple years and would buy it again if they had not messed up their compound and made it slower. But only as a rear tire. I'll never take a tire without some kind of side knobs off-road as a front tire. Maybe if all your gravel is graded and you never see ruts, but I crashed once when my G-One front could not climb out of a rut and I had a few other white knuckle moments. I never see water or mud so that is not a problem but there are a lot of ruts with soft dirt that require a bit of side traction. Even a minimal side knob like the WTB Byway was sufficient and never caused me problems on the front. My personal favorite now is an older model Thunder Burt. I would love to test the aerodynamics of the 27.5 TB I'm using now vs a 40mm 700c tire, but that is beyond me right now.
1
ccand51997
265 posts
#13Jan 27, 2021, 9:52 PM
Jumbo wrote:

Re: weights. Sure they're not everything. That's been discussed a lot, as far as I've read. But I can tell you anecdotally that switching from a bike that's 23 lbs (two years ago) to one that's around 19 has made a world of difference for me climbing. It's really night and day.

Do you mind if I ask how you measured the difference? Because 4 pounds is roughtly a 4 watt difference when climbing a steep hill which is not really earth shattering. That is why I try to bust that myth; well, not exactly a myth but a gross overestimation of importance. A good tire vs. a poor one can make more of difference than a few pounds on your bike.
1
Jumbo
123 posts
#14Jan 28, 2021, 8:18 AM
ccand51997 wrote:
Do you mind if I ask how you measured the difference? Because 4 pounds is roughtly a 4 watt difference when climbing a steep hill which is not really earth shattering. That is why I try to bust that myth; well, not exactly a myth but a gross overestimation of importance. A good tire vs. a poor one can make more of difference than a few pounds on your bike.

I don't have a power meter. That would be a fun toy, though! My feeling about the diffence comes from two sources. One, perceived effort. Obviously, subjective and subject to all manner of other potential causal factors. But it's notable that I can use higher gears with the lighter bike than on the heavier bike, and hills that previously made me question my will to live are now kind of fun. Two, segment times for climbs on this bike are always faster. Again, could have to do with fitness (though probably not, because I'm consistent in that generally) or some geo factor or whatever, but the most notable difference between the bikes I'm comparing is weight, a lot of it in the tires.

There something I've been thinking about that I feel doesn't come up as often as it should in discussions about power. Power numbers don't tell us nearly as much about real-world speed as something way more important: watts/kg. Rounding all numbers, I weigh 138lbs (62.5 kg). Suppose that 4 lbs.=a 4w difference. For me, that's .064 watts/kg. For somebody who weights 200lbs. (90.7kg), that's .044 watts/kg. So 4w is actually 32% more significant for me than the 200lb. person. Couple that with pedaling style. I use higher cadence up hills because that's what my muscles are built for. Higher cadence is lower power, right? (Correct me if I'm wrong about that!) The lower power you're generating, the higher percentage of it 4w will be (and add). So basically, unless I've got this all wrong, which is entirely possible since this stuff is complex, for a light person who rides with a high cadence, 4w is going to be a lot more significant than it will be for a heavier person who grinds up hills. And that could account for the difference I notice between my bikes.
2
Mark W. Ingalls
62 posts
#15Jan 28, 2021, 9:31 AMedited
@Jumbo, I love that your handle is Jumbo and you weigh 138 lbs. 🥰
One of the toughest kids in my high school was a 138 lb. wrestler, btw.
0
Jumbo
123 posts
#16Jan 28, 2021, 10:53 AMedited
Mark wrote:
@Jumbo, I love that your handle is Jumbo and you weigh 138 lbs. 🥰
One of the toughest kids in my high school was a 138 lb. wrestler, btw.

It's short for Jumbotron. My hillbilly robot name.

Oh, and the toughest kid in my school was named Mark W. Ingalls. 😁
0
ljsmith
762 posts
#17Jan 28, 2021, 10:54 AM
Jumbo wrote:

IHigher cadence is lower power, right? (Correct me if I'm wrong about that!) The lower power you're generating, the higher percentage of it 4w will be (and add). So basically, unless I've got this all wrong, which is entirely possible since this stuff is complex, for a light person who rides with a high cadence, 4w is going to be a lot more significant than it will be for a heavier person who grinds up hills.

power=Force x velocity
force=mass x acceleration
velocity=change in position/change in time

A higher cadence produces more velocity and therefore power. You can produce the same power at 50rpm as you can at 100rpm. At 50rpm you just have to produce twice as much force.
0
ccand51997
265 posts
#18Jan 28, 2021, 11:50 AM
Jumbo wrote:

There something I've been thinking about that I feel doesn't come up as often as it should in discussions about power. Power numbers don't tell us nearly as much about real-world speed as something way more important: watts/kg. Rounding all numbers, I weigh 138lbs (62.5 kg). Suppose that 4 lbs.=a 4w difference. For me, that's .064 watts/kg. For somebody who weights 200lbs. (90.7kg), that's .044 watts/kg. So 4w is actually 32% more significant for me.

You are not wrong in your thinking about how 4 watts will help you more as a lightwieght. But it is not a huge number. One time I read and then verified that 1 pound lighter would save you about 14 seconds from the bottom to top of Alp d"Huez. So that is roughtly 1 second for every 250 feet climbed. So your four pounds would be about 4 seconds every 250 feet climbed. If you are experiencing much more massive gains than that, then something else is in play, probably much better tires, maybe newer drivetrain and maybe just feeling better on the day. The great thing about a power meter is that it cuts through all of that and just gives you data. I've had one since 2004, off and on, and though I don't ride with it every day, when I want to test something I know I can go and get solid numbers. After an argument once, I went out and tested a 10 pound differnce over my rolling hills TT course I use and there was less than 4 seconds over 10K/18ish minutes and frankly, that is sort of within the "noise" of what I think I can test.
Now, that was an aero position at 37 to 38 kph but 10 pounds is a lot. Some people forget that filling a 24 oz water bottle is about 1.5 pounds so two of those on a long ride is 3 pounds. Unless you have a way to keep stuff constant and test you never really know what is happening. Until power meters came along, no one had a really reliable way to test things on their own.
0
Jumbo
123 posts
#19Jan 28, 2021, 12:10 PM
ljsmith wrote:

power=Force x velocity
force=mass x acceleration
velocity=change in position/change in time

A higher cadence produces more velocity and therefore power. You can produce the same power at 50rpm as you can at 100rpm. At 50rpm you just have to produce twice as much force.

I really appreciate the correction! I have like the worst education in physics.

So, just for the record, each stroke at a high cadence has higher velocity but lower force, so can come out the same power as a low cadence with lower velocity but higher force?
0
Mark W. Ingalls
62 posts
#20Jan 28, 2021, 12:42 PMedited
I like to use a logic tool called “Dimensional Analysis.” Force has the dimension, pounds (Newtons). Distance has the dimension, foot (meter). Work has the dimension, foot-pound (Newton-meter) because work involves moving a force through a distance. Energy only differs from work because of context— is it available? Power is the rate of work, with the dimension foot-pound per second (= 1.35581795 watts). Here’s the deal— When you get your electric energy bill it is for “kilowatt-hours.”

I hope that helps put force, work and energy in context. If not, ignore me ‘cause I’m a fuddy-duddy.
0

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