"Experts"

[Mark McM]

Originally Posted by bicycletricycle

Your attempts to muddy the issue do not make the situation any less silly. We aren't talking about trains or chip seal.

I repeat, the radical changes in "facts" about what the most efficient tire width / pressure, even in a limited variable environment like the track, is shocking.

They didn't even make high end tires in sizes above 25mm for years, now that is the smallest "experts" recommend.

this is a huge change that is way outside of your "well different variables call for different solutions excuse making"

The whole world of cycling was just way wrong about tire widths and pressures, or maybe was right and now we are wrong, I don't know but it is crazy.

Things always appear easy to people who have never actually tried it. Let's say you were going to try to find out the best tire width for smooth tarmac, how would you go about doing it? I guess you'd have to start by ascertaining what properties determined "smooth tarmac", how would you go about doing that? Then I suppose you'd have to come up with a way to measure the energy consumed by the tires - how would you do that? Would you try to measure the energy consumed by the tires directly, or would you make a measure of the total rolling power, and then control for all the other variables? If you were to measure rolling energy directly, now would you do that? Would you measure the force between frame and wheels (maybe a load sensor on the axles) to measure the drag experienced by the wheel? If so, how would you separate the other drag forces, such as bearing drag? Or maybe you'd measure the energy losses in the tire by measuring their temperature rise? What instrument would you use to do this? Maybe an optical pyrometer? If so, how would you account for energy dissapated while rolling, through convection to the air or conduction to the pavemnent?

Maybe instead of measuring the energy lost in the tires directly, you'll measure the total power, and then subtract out the other power losses? What additional power losses will you subtract out? Certainly aero drag, that being the largest, but how would you measure the aero drag? If a rider is riding the test bike, how do you account for rider position changes, which affects their CDA? Or maybe use a robot rider, which can accurately repeat their power and position (of course, you'd have to invent one first)? And of course, you'd have to account for winds, and air density, and all the other variables involved in air drag, how would you do that?

What, you have no answers to the above? Well, only someone who has figured out these things (and many more) would be able to do do tests to definitively figure out the best tire width on smooth tarmac.

(And that's just questions about how you'd make measurements, and not even starting to address all the variables in the construction of the thing you're trying to measure.)


Unfortunately, what you are asking is not nearly as easy as it sounds. Over time our ability to take measurements and to filter out extraneous noise has increased, but we are still no where near what it would take to answer your "simple" question.

What's that you say? We put a man on the Moon over 50 years ago, why can't we figure out the best tire width for smooth pavement? Because it's two different questions The question back then was just how to accomplish a particular goal by a particular data (at whatever the cost), not to determine the exact optimum way to do it. If you asked the Apollo engineers "What's the optimum number and diameter of nozzles for 2nd stage booster", they probably couldn't come up with an exact answers. But they could say that if you used 5 nozzles of a particular size, they could build it in time and get the job done.


All these criticisms about "Experts" not always having all the answers reminds me of this quote from George Carlin:

"Inside every cynical person, there's a disappointed idealist"

Me thinks the idealist in you somehow got the notion that it is possible to discover absolute truths; only to discover that these absolute truths rarely exist.

[krooj]

Originally Posted by bicycletricycle

Bicycle fit is weird, seems to be a strange mix of superstition and fashion.

The way people talk about / obey their bike fit….. well, just strange. Certainly they know some stuff but it ain’t a science, it’s barely an art.

I was talking to a bike builder who built a bike for a customer, they rode it around and liked it, then went to get a fit, the guy told him he couldn’t get the bike to fit him so he sold it. Well, what can you say.

At this point, I'm convinced bicycle fitting is a thinly veiled scam. I had a decent experience with Sacha last September, but most other fits have been a waste of my time. I think it boils down to two key things:

1. Nobody is really paying much attention to the spine and it's associated kinematics - this type of knowledge is way, WAY above the paygrade of someone in a bike shop, but it affects how literally every single other thing works.
2. The hard truth is that most of us need to do countervailing exercises to offset the adaptations an activity like cycling does to the body. Nobody wants to go for a fit and come away with an Rx for PT, but that's kinda what you need.

[fourflys]

Originally Posted by spoonrobot

This isn't correct. There was vocal opposition to narrow/hp as the best. For example, Jobst Brandt was besieged often for his views that max pressure narrow tires were fastest even on the rough unpaved tracks he rode between pavement sections. Bicycle magazines sometimes printed letters arguing against the experts from users arguing that they had better road results on 28/29/30mm tubulars than expected.

I don't think BT was trying to really say EVERYONE was saying this or that, he just trying to make a point.. I know that when I started riding seriously in mid-2000s, most of the riders in the San Diego Wheelman and most of the folks on here (when it was the Serotta Forum) would have said you were crazy for riding anything over a 25mm.. and actually finding quality tires at 28mm, but esp over 28mm, was pretty difficult.. this was also around the time Jan was starting to really lean in on wider tires, lower pressures, etc.. and, similar to now on his other things, folks on here would call him a kook, etc.. I was riding a Giant TCX and, later, a Salsa Las Cruces with 25mm Michelin Pro2s that plumped out to around 26-27mm on my rims (since most road forks barely fit a 25) and it was so much better than anything Conti was putting out in a 23mm or 25mm..

My point is BT's suppositions aren't wrong and I certainly don't believe he was trying to convince anyone that EVERYONE was doing something.. something more like the "royal we" concept..

[fourflys]

I think some folks on here are taking the initial (and some follow-on) posts way to seriously..

"What's the BEST xxxx?" impossible, because define "best".. you can try and quantify things like lightest, most puncture resistant, fastest (for a given surface at that snapshot in time), but you can never find "best" as that is a measurement that will always be personal to each person..

I've read several times that's one reason why bike weight (and now probably drag coefficient) is so talked about is it's one of only a few things that marketers can point and say their bike is the "best" at that metric.. doesn't mean it's the best bike for a particular rider or a particular race, only that it's the lightest currently made, etc..

but, this is to be expected when you use the term "experts" and folks who think they are get ready to battle.. https://www.psychologytoday.com/us/b...-kruger-effect

[bicycletricycle]

I understand the complexities and in no way am saying it would be easy to get a perfect answer, again, what I am saying is, it is shocking how much it has changed in such a short period of time. This makes me under what else we are getting really wrong. It also makes me wonder what we will think about tire widths 20 years from now.

Originally Posted by Mark McM

Things always appear easy to people who have never actually tried it. Let's say you were going to try to find out the best tire width for smooth tarmac, how would you go about doing it? I guess you'd have to start by ascertaining what properties determined "smooth tarmac", how would you go about doing that? Then I suppose you'd have to come up with a way to measure the energy consumed by the tires - how would you do that? Would you try to measure the energy consumed by the tires directly, or would you make a measure of the total rolling power, and then control for all the other variables? If you were to measure rolling energy directly, now would you do that? Would you measure the force between frame and wheels (maybe a load sensor on the axles) to measure the drag experienced by the wheel? If so, how would you separate the other drag forces, such as bearing drag? Or maybe you'd measure the energy losses in the tire by measuring their temperature rise? What instrument would you use to do this? Maybe an optical pyrometer? If so, how would you account for energy dissapated while rolling, through convection to the air or conduction to the pavemnent?

Maybe instead of measuring the energy lost in the tires directly, you'll measure the total power, and then subtract out the other power losses? What additional power losses will you subtract out? Certainly aero drag, that being the largest, but how would you measure the aero drag? If a rider is riding the test bike, how do you account for rider position changes, which affects their CDA? Or maybe use a robot rider, which can accurately repeat their power and position (of course, you'd have to invent one first)? And of course, you'd have to account for winds, and air density, and all the other variables involved in air drag, how would you do that?

What, you have no answers to the above? Well, only someone who has figured out these things (and many more) would be able to do do tests to definitively figure out the best tire width on smooth tarmac.

(And that's just questions about how you'd make measurements, and not even starting to address all the variables in the construction of the thing you're trying to measure.)


Unfortunately, what you are asking is not nearly as easy as it sounds. Over time our ability to take measurements and to filter out extraneous noise has increased, but we are still no where near what it would take to answer your "simple" question.

What's that you say? We put a man on the Moon over 50 years ago, why can't we figure out the best tire width for smooth pavement? Because it's two different questions The question back then was just how to accomplish a particular goal by a particular data (at whatever the cost), not to determine the exact optimum way to do it. If you asked the Apollo engineers "What's the optimum number and diameter of nozzles for 2nd stage booster", they probably couldn't come up with an exact answers. But they could say that if you used 5 nozzles of a particular size, they could build it in time and get the job done.


All these criticisms about "Experts" not always having all the answers reminds me of this quote from George Carlin:

"Inside every cynical person, there's a disappointed idealist"

Me thinks the idealist in you somehow got the notion that it is possible to discover absolute truths; only to discover that these absolute truths rarely exist.

[bicycletricycle]

Yes, this is what I am trying to say. Thank you for translating.

Originally Posted by fourflys

I don't think BT was trying to really say EVERYONE was saying this or that, he just trying to make a point.. I know that when I started riding seriously in mid-2000s, most of the riders in the San Diego Wheelman and most of the folks on here (when it was the Serotta Forum) would have said you were crazy for riding anything over a 25mm.. and actually finding quality tires at 28mm, but esp over 28mm, was pretty difficult.. this was also around the time Jan was starting to really lean in on wider tires, lower pressures, etc.. and, similar to now on his other things, folks on here would call him a kook, etc.. I was riding a Giant TCX and, later, a Salsa Las Cruces with 25mm Michelin Pro2s that plumped out to around 26-27mm on my rims (since most road forks barely fit a 25) and it was so much better than anything Conti was putting out in a 23mm or 25mm..

My point is BT's suppositions aren't wrong and I certainly don't believe he was trying to convince anyone that EVERYONE was doing something.. something more like the "royal we" concept..

[bicycletricycle]

The human body is about as complex as things get, even more complex because of its adaptive qualities.

I feel like bike fit is strange because it can have a lot of different goals that would require different approaches and different backgrounds for the fitter to accomplish. Goals can be pretty varied, relieving a specific pain, adapting to some injury or body limitation, maximizing performance, finding a position that will give you the longest cycling career with the least long term adverse effects (cycling is not a natural activity).

I feel like most bike fitters don't have enough knowledge to do any of these very well. (to be clear I am not claiming I do either). It seems like they basically apply whatever trend in fit is popular mixed with what has worked for them, which I guess is okay as long as it is stated that way.

Most fits are slightly above the level of a tailor adjusting a suit (I am by no means demeaning tailors and suit making, to do this well is an admirable skill) but for some reason they are treated more like a consult with a doctor.

Originally Posted by krooj

At this point, I'm convinced bicycle fitting is a thinly veiled scam. I had a decent experience with Sacha last September, but most other fits have been a waste of my time. I think it boils down to two key things:

1. Nobody is really paying much attention to the spine and it's associated kinematics - this type of knowledge is way, WAY above the paygrade of someone in a bike shop, but it affects how literally every single other thing works.
2. The hard truth is that most of us need to do countervailing exercises to offset the adaptations an activity like cycling does to the body. Nobody wants to go for a fit and come away with an Rx for PT, but that's kinda what you need.

[bicycletricycle]

Ya, I agree with all of this. there are always a few people in just about every camp at any one time. I am not actually claiming every single person on a bicycle got it wrong, who would claim that?

Maybe in the future we will all be on 17" wheels with suspension, I will write a post saying how crazy it is that we all got the wheel size thing so wrong for so long and you will say,

well actually, Sir Alex Moulton blah blah blah blah....

Ya, I know.

Originally Posted by spoonrobot

This isn't correct. There was vocal opposition to narrow/hp as the best. For example, Jobst Brandt was besieged often for his views that max pressure narrow tires were fastest even on the rough unpaved tracks he rode between pavement sections. Bicycle magazines sometimes printed letters arguing against the experts from users arguing that they had better road results on 28/29/30mm tubulars than expected.

I don't disagree with your broad point, but glossing everything from the post together as a monolith isn't an accurate representation. We can look back at the past as settled science based on the idea that what we know now had to be the most common and accepted because, we know about it now, but that isn't correct. So much information from the past never made it into the computer age, and so much of that information was from the outskirts, the opposition, the smaller groups of minority thought.

You can find all sorts of scans from old bicycle magazines and catalogs of marketing materials or reviews or technical details but it's very hard to find scans of letters and op-eds from the public which were also published in every issue.

I'm reminded of a short anecdote I experienced last year. I was loaned a big batch of Bicycle Guide issues from the early-mid-1990s.

Bicycle Guide covered road and mountain and eventually spun off the road stuff into Bicyclist. The first issue of Bicyclist the editor Garrett Lai wrote an introduction to the new magazine and how the Road-Only direction was going to go. He mentioned that the magazine was successful covering both MTB and Road back when it was Bicycle Guide, that nobody complained and the spin-off was to better serve each group of cyclists.

Well, as I worked through the magazines I found that wasn't true. Almost every issue from the early 1990s had letters to the editor complaining about MTB coverage and how the subscriber wanted less or no MTB and more Road. Dozens and dozens of letters.

My point is that it's easy to view the past from a forward looking perspective. It's easy to get caught up in the current messaging and marketing. It's easy to forget that people in the past may have been just as curious and disagreeable as they are today and done the best with the information and iteration they were able to generate. We will never know every opinion or idea from the past but we can be sure that our view of what it was like will most likely get worse as it recedes into the distance.

[pmarkos]

I appreciate this post. I've been feeling the bike bs lately and it's disheartening. I haven't stopped riding. I'm just not willing to buy things to try trends. I'm only guessing but it seems like others aren't either. I haven't read all the posts so I don't know if some has brought this up. I think cycling is an industry driven by sales instead of knowledge. I hate it more and more, but under those circumstance knowledge gets manipulated to generate sales or to minimize a bottom line to maximize profit. From some of the post I've read it sounds like some have taken the perspective that it's an individual journey to understand what you like about bikes. I get that, for me it just has resulted in liking very little about the bike industry. Or at least what I understand about the industry. Does anyone know are there (non biased) journals around bike science?

[Chris]

I work in medicine. What I tell our patients is that medicine is based on the average person, but it’s the rare person who is average. We start by throwing the first dart (average) at the dart board and we adjust from there. I think it’s the same thing with bike fit.

[Wakatel_Luum]

Originally Posted by bicycletricycle

Remember all those amazing theories about crank length being a percentage of leg length yielding 200mm plus cranks for tall people? Nope, everyone on 165's now.

Knee over center of axle?
axle centered under ball of foot?

According to the "expert" interviewed on this podcast 175mm cranks are fine, depending on hip location yad yada yada yada.

Worth listening to but taken with a pinch of salt.

https://escapecollective.com/review-...about-saddles/

[martl]

Originally Posted by Chris

I work in medicine. What I tell our patients is that medicine is based on the average person, but it’s the rare person who is average. We start by throwing the first dart (average) at the dart board and we adjust from there. I think it’s the same thing with bike fit.

I disagree that the average person should be "rare". About 85% of the general population is close enough to the "average person" for cures to work, and epecially so for body geometry etc.
But it seems that 85% of the cycling general public is somehow a member of the other 15%. don't we all like to feel special

[Elefantino]

Originally Posted by Peter P.

Add "aero" to the list.

.

[Black Dog]

Originally Posted by Elefantino

.

That is the ad that sums up the industry. I am not talking about the aero claim.

[gravelreformist]

My recollection from the 1990's/early 2000's era was that we were on the cusp of making a lot of these discoveries just by trial and error - but without data, testing by feel takes a lot of time - and a lot of effort is expended going the wrong direction.

However, we were advising riders in our shop at that time that 90psi was the sweet spot for the 23mm tires everyone was riding on our chipseal roads. That pretty well matches with what Silca's calculator suggests today.

We were running as little as 15psi in cross tubulars depending on conditions. At the top levels, it was almost impossible to be competitive on clinchers because you couldn't reliably run them at less than 35psi.

We also discovered that cross bikes with their 700c wheels were remarkably manageable on terrain that was often considered mountain bikes only at that time. The larger wheels rolled so much better than the 26" MTB wheels that they largely made up for the lack of suspension.

Those same bikes were also capable of mostly keeping up with those 23mm road bikes on pavement group rides. And as a result, our cross bikes were our first gravel bikes. Mostly limited by tire clearance, tire availablility, limited low gearing, and brakes.

I was put on 165mm cranks when being fit for my custom team race bike circa 1998. I still have that bike on the trainer today.

So I think that even 30 years ago, we were on the right track even if we couldn't strictly quantify why these things worked.