Old myths or established facts.

[Rock Creek Rider]

Before Americans, and by Americans I mean citizens of the US, started racing professionally in Europe, Greg LeMond in particular, there were a lot of myths about cycling going around. I was victim to a few. I think I mentioned the myth about ankleing in a previous post. Another one, I consider a myth, is the one about training on a fixed gear bike. Greg LeMond, the only American to win the tour and not have his victories taken away, "debunked" that one in his book. I haven't heard of any European professional teams training of fixed gear bikes. Maybe some do, but the idea makes no sense to me.
For years and years I was convinced that rotating mass (tires, wheels, pedals, shoes, cranks) had a greater affect on performance than non rotating mass. It is harder to accelerate rotating mass, but at a steady speed, there is no difference and may, in fact, help by steadying your speed. There may be little difference in effect between the two.
It was considered fact that a stiff frame is more efficient that a more flexible one. Boy, I've seen conflicting evidence on that one. I think there is more evidence that it is true, but then there is the thing about horizontal stiffness vs. vertical compliance. Some claim that you can make an efficiently stiff bike without it being harsh riding. Anyone that has stood and pedaled on a bike with suspension knows that bouncing up and down takes away power too, so I'm inclined to think vertical compliance hurts too.
Always thought hard, skinny tires were faster, but now they are saying that fatter tires with a little less air have lower rolling resistance. Maybe, but does that take into account energy lost from side to side tire deformation, as you pedal? I don't think it does. I also notice that on my indoor trainer, it is way harder to pedal if the tire pressure is low. I'm not convinced that fatter, lower pressure tires are faster.
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[cyclintom]

Before Americans, and by Americans I mean citizens of the US, started racing professionally in Europe, Greg LeMond in particular, there were a lot of myths about cycling going around. I was victim to a few. I think I mentioned the myth about ankleing in a previous post. Another one, I consider a myth, is the one about training on a fixed gear bike. Greg LeMond, the only American to win the tour and not have his victories taken away, "debunked" that one in his book. I haven't heard of any European professional teams training of fixed gear bikes. Maybe some do, but the idea makes no sense to me.
For years and years I was convinced that rotating mass (tires, wheels, pedals, shoes, cranks) had a greater affect on performance than non rotating mass. It is harder to accelerate rotating mass, but at a steady speed, there is no difference and may, in fact, help by steadying your speed. There may be little difference in effect between the two.
It was considered fact that a stiff frame is more efficient that a more flexible one. Boy, I've seen conflicting evidence on that one. I think there is more evidence that it is true, but then there is the thing about horizontal stiffness vs. vertical compliance. Some claim that you can make an efficiently stiff bike without it being harsh riding. Anyone that has stood and pedaled on a bike with suspension knows that bouncing up and down takes away power too, so I'm inclined to think vertical compliance hurts too.
Always thought hard, skinny tires were faster, but now they are saying that fatter tires with a little less air have lower rolling resistance. Maybe, but does that take into account energy lost from side to side tire deformation, as you pedal? I don't think it does. I also notice that on my indoor trainer, it is way harder to pedal if the tire pressure is low. I'm not convinced that fatter, lower pressure tires are faster.
.

Well, to address some of these so-called "myths"; They used to train on fixed gear bikes or race track in the off season because it actually does force you to learn how to pedal circles. So it has nothing to do with mass and everything to do with training technique.

Any compliance in the frame and fork is probably bad. But that's part of the reason that they are going to fatter, lower pressure tires. This gives a road bike about as much compliance as it needs and at the same time limits total travel via pneumatic pressure. Compliance in a frame gives far greater travel which in turn can cause handling problems.

On a perfectly hard smooth surface higher pressure narrower tires are faster. But that isn't realistic. Because asphalt isn't smooth a wider tire has a wider and less lengthy contact patch. This keeps the longer, narrower contact patch from pressing more deeply into the road grooves and acting like a suction cup when it reaches the end of the contact patch. Under any conditions it limits the amount of time any part of the contact patch is on the road.

There most definitely are limits. The racers are using 26 and 27 mm tires. If you go wider for any specific loading (combined rider and bike weight) you end up with more surface area in the contact patch and more rolling resistance. So it is not all cut and dried. And if you go lower pressure than necessary to achieve the same AREA of contact patch again you increase the rolling resistance.

 

[dabac]

Sometimes it's very hard to distinguish myths from something that's true, but only under certain circumstances.
"True" for you doesn't have to be "true" for me. Or even true for this ride but not for that ride
And what's always hard to factor in is that nastily uncalibrated, unlinear lump of biomass perched on top of the bike messing up the aerodynamics.

Take tire width/tire pressure for instance.
If you were to use a tire wheel w/o any "give" at all, even the smallest thing protruding above the surface of the road would force the bike upwards.
And the energy for going up would come from going forward.
And some of it will be transferred into your hands, feet and butt.
So looking at the bike only, it makes sense to go for a lower pressure where some lumps and bumps can be allowed to sink into the tire instead, to avoid that vertical kick.
Looking at bike + rider, you're then forced to consider fatigue too.
Ths is sometimes well demonstrated in MTB XC racing.
Well-equipped riders choose between rigid, HT and FS depending on both course length and roughness.
The bike that's the fastest for one loop of a circuit might not be the bike that's fastest for 10 loops of the circuit simply because by the 3rd lap, the one-loop-fastest bike has turned the rider into a state most aptly described as "well tenderized".

Rotating mass is another one of those so-so things.
And you're right, during steady-state riding it doesn't matter.
So when does a ride turn from steady-state to dynamic?
Again, the rider becomes an issue.
Less rotating mass makes a big change to the feel of the bike. It's easier to push yourself if you feel the benefit from each separate effort.
If you don't feel the response, it gets so much easier to simply muddle through.

 

[cyclintom]

Its winter

Sometimes it's very hard to distinguish myths from something that's true, but only under certain circumstances.
"True" for you doesn't have to be "true" for me. Or even true for this ride but not for that ride
And what's always hard to factor in is that nastily uncalibrated, unlinear lump of biomass perched on top of the bike messing up the aerodynamics.

Take tire width/tire pressure for instance.
If you were to use a tire wheel w/o any "give" at all, even the smallest thing protruding above the surface of the road would force the bike upwards.
And the energy for going up would come from going forward.
And some of it will be transferred into your hands, feet and butt.
So looking at the bike only, it makes sense to go for a lower pressure where some lumps and bumps can be allowed to sink into the tire instead, to avoid that vertical kick.
Looking at bike + rider, you're then forced to consider fatigue too.
Ths is sometimes well demonstrated in MTB XC racing.
Well-equipped riders choose between rigid, HT and FS depending on both course length and roughness.
The bike that's the fastest for one loop of a circuit might not be the bike that's fastest for 10 loops of the circuit simply because by the 3rd lap, the one-loop-fastest bike has turned the rider into a state most aptly described as "well tenderized".

Rotating mass is another one of those so-so things.
And you're right, during steady-state riding it doesn't matter.
So when does a ride turn from steady-state to dynamic?
Again, the rider becomes an issue.
Less rotating mass makes a big change to the feel of the bike. It's easier to push yourself if you feel the benefit from each separate effort.
If you don't feel the response, it gets so much easier to simply muddle through.

now in he bay area so riding drops rather dramatically. When it picks up again in the spring, I find that I try to ride as "normal". But I can't hold a steady pace and so I pedal for awhile and then coast. As the season picks up I get back to the point where I can pedal a constant pace. This also causes a problem since I ride drag most of the time so that we don't lose riders out of the group and most of them aren't as fast so I keep overrunning them and have to back off.

Finally this becomes irritating enough that I start doing singular rides for awhile until I can ride with the fast group. Then since I can't keep up on the climbs I get to catch them on the downhills or flats. But there are signs that that might be changing. The oldest of them is about 5 years younger than me and they are beginning to show the signs of aging (finally) and health issues and all those assholes that rode away in a flash the last two years are now not that fast anymore. Though we still have some Jack-the-Flashes.

 

[Froze]

Tom's an old myth with no established facts!

 

[BrianNystrom]

I have no idea what Lemond's claims about it are, but fixed-gear riding has several benefits. Back when I was racing (just before Lemond turned pro), I found that it definitely helped to build leg speed and a smoother pedal stroke at higher RPMs. The negative resistance from braking with your legs builds strength, but it can be hard on the knees, so you have to be careful. As much as anything else, riding a fixed gear is a fun change of pace. Riding a bike that's stripped down to its very essence is a completely different experience from riding a road, gravel or mountain bike. Are the major benefits to riding a fixed-gear bike in the off-season? I don't know, but I don't see where it can hurt unless you're doing it in hilly terrain with inadequate base mileage. BTW, although back in the day I did occasionally ride a track bike on the road (no brakes), I wouldn't even consider it now and wouldn't recommend it except on a closed course, as it's simply not worth the risk.

Rotating mass is important when climbing due to the constant acceleration-deceleration with each pedal stroke, but less so in steady-state riding at higher speeds where aerodynamics is much more of a factor. That's why pros typically ride lightweight, semi-aero wheels in mountainous races/stages and more aero wheels when the terrain is flatter.

Regarding compliance:

I guess I'll have to debunk some of Tom's BS. Pros are riding wider tires because they have less rolling resistance (due to lower hysteresis losses, not some made-up "suction") and with properly matched wheels, they have less aerodynamic drag as well. The reduced rolling resistance/hysteresis is due to the shape of the contact patch; a shorter, wider contact patch defects the tires casing less and less energy is lost as friction-created heat. There is a limit to how wide you can go and still maintain these benefits, which currently seems to be somewhere around the 26-28mm range.

The major source of compliance on road bikes is and always has been the tires. Even back when 20mm tubulars were the norm for racing and riders were on relatively flexible steel frames, the tires were still the major factor. I defy Tom to show me any standard road frame that can provide 20mm of compliance. I'm not talking about suspension forks or Softride beams or any of that nonsense, I mean a real road frame. The truth is that and compliance from the frame is secondary to that provided by the tires.

Flexible frames can cause handling problems, but it's because they allow the wheels to deflect laterally and not track in the same plane. Consequently, lateral stiffness is critical to a well-handling bike. OTOH, excessive vertical stiffness can adversely affect handling by causing the bike to bounce on a rough surface. Vertical compliance has been shown to improve handling while also enhancing rider comfort. There are limits to this too, but it doesn't take a lot of vertical compliance to produce major benefits on a road bike. That's clearly evident if you spend any time testing different tire pressures. Speaking of which, the trend now it toward lower pressures at any given tire size, as it has been demonstrated that it results in less rolling resistance on anything less than a perfect surface and greatly reduces rider fatigue.

Modern carbon-fiber frames permit a level of independently tuning lateral and vertical compliance that simply hasn't been possible with metal frames. Advances like hydro-formed tubing have narrowed the gap somewhat, but carbon fiber is still king when it comes to fine-tuning handling and compliance characteristics.

There is another common misconception about tire pressure and width; wider tires are not automatically more comfortable. If you compare narrow and wider tires at pressures where they have the same contact patch area, they will feel the same in terms of compliance. However, wider tires allow you to reduce the pressure because they deflect more before bottoming out on the rim. Consequently, you can run lower pressure and increase your comfort. The contact patch area will increase, but the lower rolling resistance of the wider tire will at least partially compensate for the increased resistance of the larger contact patch. The end result is a gain in comfort with little or no sacrifice in rolling resistance.

FWIW, at 170 pounds, I run 25mm road tires on narrow (20mm) road rims at 70/80 psi, front/rear. I ride crappy New England roads and have never had a pinch flat. I arrived at these pressures after playing with them pretty extensively. If I go lower, the ride will start to get bouncy when I get out of the saddle. If I go higher, I can definitely feel the difference in harshness. Both of my road frames (Cannondale SuperSix Hi-Mod and Look 585) are quite stiff with no compliance-enhancing features, but they're comfortable for long rides at these tire pressures. I can't say that I've ever detected any difference in rolling resistance at any pressure that I've tested, so I can only conclude that whatever differences exist are masked by the difference in compliance/comfort.

 

[dabac]

Its winter

now in he bay area so riding drops rather dramatically. When it picks up again in the spring, I find that I try to ride as "normal". But I can't hold a steady pace and so I pedal for awhile and then coast. As the season picks up I get back to the point where I can pedal a constant pace. This also causes a problem since I ride drag most of the time so that we don't lose riders out of the group and most of them aren't as fast so I keep overrunning them and have to back off.

Finally this becomes irritating enough that I start doing singular rides for awhile until I can ride with the fast group. Then since I can't keep up on the climbs I get to catch them on the downhills or flats. But there are signs that that might be changing. The oldest of them is about 5 years younger than me and they are beginning to show the signs of aging (finally) and health issues and all those assholes that rode away in a flash the last two years are now not that fast anymore. Though we still have some Jack-the-Flashes.

And what has this got to do with what I wrote?
You’re usually not the guy who needs an excuse to ramble on.

 

[BrianNystrom]

Go look at what he posted in the Dangers of Carbon Fiber Wheels thread. I don't know whether these "brain dumps" are more funny or disturbing.

 

[Froze]

Go look at what he posted in the Dangers of Carbon Fiber Wheels thread. I don't know whether these "brain dumps" are more funny or disturbing.

They're disturbing because he does that very frequently unless he copies and pastes stuff off the internet, but you can tell when he does that because his spelling and grammar changes from bad to good which is not the way he writes.

Brian I have a question about tire size. I mentioned this earlier but not sure if you saw it. You spoke of slightly larger tire size, which I take it to mean going from 23 to 25, having less rolling resistance, and I've seen the studies that pretty much support that; however aerodynamics is an odd one to figure out since I haven't seen any studies on that aspect of tires yet. So wouldn't it make sense that a narrower tire on the front, like a 23, would be more aerodynamic than a wider 25? So since the air rushing toward a bicycle at say 25 mph first hits the front of the bike which includes the front tire wouldn't you want that tire to slice through the wind faster?

For the rear tire since the air disturbance has already been screwed up with due to the bike and rider, and since the rear tire is partially protected from the wind by the seat tube wouldn't going with a 25 tire would be better to take advantage of the lessor rolling resistance?

The reason I asked that was because back sometime in the 80's there was a test done with a full disk wheel in the back, which is how time trial guys use to run TT's, and there was some improvement on speed, but then somebody thought, wait, isn't that backwards? shouldn't the disk be in the front? So he had it tested both ways and by placing the disk in the front it significantly improved the speed of the bike. Of course with a disk in the front you have could have some dangerous handling effects if it's even a little breezy, but on a calm day this seems, according to the report I saw, would work the best. So that goes back to my thoughts about having the narrower tire on the front, it also would, or should, mean that front wheels could have a 35 to 45 mm deep dish to it while the rear could be 25 to 30, but instead you see people with the deeper rims in the back where it's doing the least amount of good...at least according to the report I read.

 

[BrianNystrom]

It's well-established that wider tires have lower rolling resistance (up to a point), but I agree that it intuitively makes sense that narrower tires should have lower aero drag due to lower frontal area. I suspect that the reason that wider tires are being touted as providing an aero advantage has little to do with the tires, but rather with the wider rims that they're mounted to. While I don't claim to understand all of the physics involved, the upshot is that it has been shown that wider, blunt-torroid-profile rims have lower drag at the typical yaw angles seen in bicycles than narrower rims. Wider tires are needed to match the profile of the rims and complete the aerodynamic "system", with some manufacturers like Mavic making matched tire and rim combinations to achieve the lowest possible aero drag. A narrower tire on a wide rim wouldn't provide any aero advantage, since the frontal area remains the same (it's determined by the width of the rim).

As you said, the biggest issue with front wheel depth is handling in wind. Disk front wheels are sometimes used in indoor track racing where there is no concern about wind. The reason that rear disks are used outdoors is that they provide reduced drag compared to a deep-section rim and a rear disk doesn't create handling problem in reasonable wind conditions that would be sketchy with a disk in front. However, in windy TTs, you'll seen riders using deep-section rims rather than disks in the rear and shallower rims in the front.

Does that help?

 

[dabac]

To chime in:
- there’s a crossover point where a wider - but ”better” profile ” creates less drag than a thinner - but ”poorer” profile. Frontal area alone doesn’t rule the roost. This is the niche that made CF and aluminium spokes not entirely stupid.
- front vs rear is a compromise in handling vs aero. Rear wheel carries more weight and isn’t free to flop around. Even though it does less good, a high profile/disc rear wheel also does less damage in windy conditions.

 

[BrianNystrom]

Agreed.

 

[Froze]

thanks guys, I do understand that, but of course having not been brought up in this world when I was racing still leaves me with some questions, sorry! LOL!!

How would a rim that was designed to be wider with aero in mind of course, but instead of being only matched to 25c tire it was instead matched to a 23c tire? would the aeroness of the rim along with the narrower profile of the tire be enough to compensate and provide a benefit for the lack of using a wider tire with wider rim on the front?

Like I said I do understand the wind situation of a deeper profile rim on the front, but is a deeper rear wheel in the back actually doing much at all if the most of the wind is blocked by the frame and rider?

This stuff I'm questioning did indeed come from studies I read some years ago about how people have this deep rim stuff backwards due to what was learned from TRACK racing as Brian mentioned. The study said that in reality a rider would be better off with a 45mm rim on the front and a 25 or so on the rear since the effect of an aero rim is minimalized on the rear. And in light of that newer TT bikes have the rear tire actually in a valley formed by the seat tube that protects the rear wheel from wind, so how is any aero effect being helped by the rim if the the whole idea the shrouded tire is to prevent wind from hitting it? As you can see from the below picture of TT bike, note how well that rear tire/wheel is protected by the incoming wind by not only the whole bike but also the seat tube, is a deep rim really effective if the design of the bike is to prevent airflow to the wheel and tire? And note here how they have the deeper dish in the rear vs the front, of course handling would be an issue, so why not have the front as it is with a shallow lightweight 25mm deep rim? details about the bike is here: https://ride.diamondback.com/andean

Now of course that study I remember is quite old so I know it, and myself, is out of date with the newer discoveries, so I'm trying to make sure I get my brain wrapped around the new logic more completely. And also for many years they always thought that a narrower front tire would slice through the wind better, which again is why I asked the question again but changed the question to reflect a wider rim for aerodynamics but designed for a 23c tire. Like I said it's difficult after years and years of studying, both in the technology world (not me, I was just a racer), and that information comes down to our level and we were told one thing only to find out years and years later that all of that is wrong. So I promise once I read your stuff on my newer formatted questions I should have a more concrete thought on all of this.

 

[BrianNystrom]

The tire needs to complete the profile of the rim and the rim manufacturers specify the recommended tire width to accomplish this. A tire that's narrower than the rim may be less than optimal in this regard. The same would be true for one that's too wide.

My understanding is that the major reduction in wheel aero drag with the new wider designs is due to improved airflow separation off the trailing edge of the front of the wheel. Don't take that as gospel, but I'm pretty sure it's correct.

When thinking about aero drag, you have to keep in mind that it's not all about air flowing over the bike in a straight line from front to back. Air hits the bike at a variety of yaw angles, up to about 15 degrees under common conditions, so the rear wheel is not always in the wind shadow of the frame.

 

[Froze]

So why can't they improve the airflow off the trailing edge of the front wheel with a narrower rim that can use a 23c tire that would fit that airflow concept that takes place with a rim that fits a 25c? I promise you I'm not brain damaged, just wanting to know how this stuff works! LOL!

The yaw thing was interesting, I would have thought that if you riding at 20 plus mph, that the wind wouldn't be able to effect the yaw degrees unless it was really breezy that day. Which is probably why Flo Wheels had this chart:

This was to show that most riders spend riding at yaw angles less than 10%. Even with yaw angles wouldn't the bike benefit more from deep rims in the front vs the rear since the the angles are usually less than 10% anyways?

 

[BrianNystrom]

I've seen similar yaw data. This is why wheel manufacturers don't typically optimize for more than 15 degrees yaw angle; riders simply don't encounter anything more than that often during riding/racing.

As for the width of the rim, I have no idea. I guess you'd have to ask an engineer at one of the wheel manufacturers, though perhaps someone like Leonard Zinn may have some answers.

 

[CAMPYBOB]

So why can't they improve the airflow off the trailing edge of the front wheel with a narrower rim that can use a 23c tire that would fit that airflow concept that takes place with a rim that fits a 25c?

Has to be marketing. At least in regards to aero. Track riders and at least 'some' pro ITT riders are still using 23 and narrower rubber (up front). You would think two of the fastest disciplines in cycling would be all over wider for aero? I read about a lot of 23F/25R ITT setups on CN. Why? No clue. Must work OK enough for some of the fast guys.

Also, a 23 tire on a rim designed for a 25 will usually just lay out to meet the rim. It may not be optimum for handling, but aero wise how much difference can there be to a 25 on that same rim? See also the 105% rule and all that jazz.

I don't notice any difference that amounts to anything, between 23's and 25's, as far as ride goes, but that could be chalked up to my low weight, air pressure, tire brand/mode differences, frame characteristics, etc. Doing an exact comparison would require a duplicate set of wheels mounted with matching rubber. There is probably a contact patch/handling advantage to the wider rubber, but I haven't failed to come out of a corner yet on my 23's. Aero? Who knows? I don't own a wind tunnel and don't do 40 Km ITT's at 40+ KPH. Moot point to me.

 

[BrianNystrom]

I doubt that marketing has much - if anything - to do with it. Wind tunnel numbers don't lie and there's absolutely no point in making wider rims that are also heavier and more costly if there aren't clear aero benefits.

You really cannot directly compare road and track riding, as track riders don't see the same yaw angles that road riders do.

As for TTs, the higher speeds compared to road racing reduce the yaw angles experienced, so perhaps there's something to be gained with a narrower front tire & rim combination. This may also be dependent on the prevailing wind conditions.

Putting a 23mm tire on a rim designed for 25s changes the profile at the front and the depth from front-to-rear. If you're comparing a carefully-engineering 25mm tire/rim combo (Mavic does this), to the same rim with a 23mm tire, there may be some increase in drag. Of course, this would vary based on the particular combination and perhaps on the wind conditions. Without wind-tunnel testing, there's really no way to know.

It's a moot point for me as well, as the only wide rims I own are on off-road bikes and I don't currently own any deep-section aero wheels.

 

[cyclintom]

I'm still waiting to see you use the term "hysteresis losses" again. I don't think you understand what the term is. This wasn't used out of electronics much but became increasingly used on anything that showed a different recovery rate for an input. In our case - the energy that is required to distort the tire is offset by the slower recovery rate of the rubber molecules rubbing against each other and causing frictional losses.

While tire compounds vary in their hysteresis losses wider tires using the same compound ALWAYS have higher hysteresis losses. This is why many tests show that 25 mm, or so, tires are the "ideal" size - the increasingly shallower contact patch of wider tires is made up for by the increasing hysteresis losses from additional rubber distortion.

And riding 20 mm tires at 150 psi which was normal, I would LOVE to see you show that they had the slightest "compliance". Those older very shallow tires on those paper thin rims had all of the compliance in the rims and spokes.

On sew-ups you could distort the rims so far as to pull the tires off. If there was compliance in the tire you couldn't do that. This used to be blamed on faulty glue jobs which were done even by professionals.

I agree that steel frames had very little compliance but it was an order of magnitude more than the carbon fiber frames. About the third generation of carbon fiber frames, such as my Time VX, simply could not be ridden with 23 mm tires unless you had a crotch of concrete. Moving to wider softer tires made the bike not just ridable but a very nice handling bike indeed. And steel forks did have quite a bit of compliance. There used to be slow-mo pictures of the Paris-Roubaix riders and the vertical compliance of those fork legs was plain as day.

I don't think that your Look has any compliance at all. My brother has one and he is slightly lighter than you. He uses those coverless carbon fiber saddles and breaks one about every six months. I can't get him to go to a stronger saddle because he's a weight weenie.

I doubt that marketing has much - if anything - to do with it. Wind tunnel numbers don't lie and there's absolutely no point in making wider rims that are also heavier and more costly if there aren't clear aero benefits.

You really cannot directly compare road and track riding, as track riders don't see the same yaw angles that road riders do.

As for TTs, the higher speeds compared to road racing reduce the yaw angles experienced, so perhaps there's something to be gained with a narrower front tire & rim combination. This may also be dependent on the prevailing wind conditions.

Putting a 23mm tire on a rim designed for 25s changes the profile at the front and the depth from front-to-rear. If you're comparing a carefully-engineering 25mm tire/rim combo (Mavic does this), to the same rim with a 23mm tire, there may be some increase in drag. Of course, this would vary based on the particular combination and perhaps on the wind conditions. Without wind-tunnel testing, there's really no way to know.

It's a moot point for me as well, as the only wide rims I own are on off-road bikes and I don't currently own any deep-section aero wheels.

From memory, it isn't the inside width of the rim but the outside. The most aero rim/tire combination has something like a 1.5 mm wider tire than rim on each side. Assuming aero rims.

 

[BrianNystrom]

Well Tom, since you've taken a calm tone in this post, I'll respond in kind.

I'm still waiting to see you use the term "hysteresis losses" again. I don't think you understand what the term is. This wasn't used out of electronics much but became increasingly used on anything that showed a different recovery rate for an input. In our case - the energy that is required to distort the tire is offset by the slower recovery rate of the rubber molecules rubbing against each other and causing frictional losses.

While tire compounds vary in their hysteresis losses wider tires using the same compound ALWAYS have higher hysteresis losses. This is why many tests show that 25 mm, or so, tires are the "ideal" size - the increasingly shallower contact patch of wider tires is made up for by the increasing hysteresis losses from additional rubber distortion.

While that may be true with car tires, which have a contact patch that is wider than it is long, it's not true for bicycle tires that have a contact patch that's much longer than it is wide. The longer contact patch increases tire deformation and internal friction. This has been published in many places by bicycle tire manufacturers and it explains why wider bicycle tires have less rolling resistance. If you don't believe me, go to their sites and check it out. It's their data, not my opinion.

And riding 20 mm tires at 150 psi which was normal, I would LOVE to see you show that they had the slightest "compliance".

Who is talking about 20mm tires at 150psi? You're bringing up something that's not even relevant to the discussion. FWIW, even when I was racing on 20mm tubulars, I never ran more than 120psi in them and typically ran 110psi or less.

Those older very shallow tires on those paper thin rims had all of the compliance in the rims and spokes.

Again, this is not even close to true. Rims were not "paper thin", even the 199-gram HI-E rims I used at one point. Yes, they were shallow section, but they were also supported by many more spokes than we typically use today. All of my racing wheels from back in the day were 36 spokes (some of the Hi-E wheels I built had more than that, but that's another discussion). Wheels with 32 spokes were considered light and 28s were typically for time trials only. These days, I'm riding 24-spoke wheels.

Regardless, The major compliance is and always has been in the tires. Otherwise, the wheels would fail in short order as I explained above. I've built and rebuilt something on the order of 1000 wheels, so I know a bit about how they work.

On sew-ups you could distort the rims so far as to pull the tires off. If there was compliance in the tire you couldn't do that. This used to be blamed on faulty glue jobs which were done even by professionals.

I rode tubulars for 36 years, so I think I can speak with some authority on the subject. Your first statement makes no sense. Assuming that what you mean is that you could deflect the rim toward the hub enough that the tire could come loose, that's simply not true.

First off, if the rim actually deflected that much, the spokes would go slack in the load affected zone, they'd fatigue quickly as a result and would be snapping like popcorn. That was never an issue.

Second, a good glue job will adhere to the rim up to the point where it actually breaks. I've seen this MANY times and in most cases the base tape separated from the tire and remained adhered to the broken rim.

I agree that steel frames had very little compliance but it was an order of magnitude more than the carbon fiber frames.

While that may have been true with carbon fiber frames of a few years back, it's not true of the most recent generation (the last 5 years or so, depending on the manufacturer), which have compliance features designed in. You can still buy an ultra-stiff carbon frame if you want one, but there are lots of options now.

About the third generation of carbon fiber frames, such as my Time VX, simply could not be ridden with 23 mm tires unless you had a crotch of concrete. Moving to wider softer tires made the bike not just ridable but a very nice handling bike indeed.

I could say the same thing about both of my road bikes, although not to that extreme. They're both a bit harsh with narrower tires at higher pressure than I currently run.

And steel forks did have quite a bit of compliance. There used to be slow-mo pictures of the Paris-Roubaix riders and the vertical compliance of those fork legs was plain as day.

Nobody is disputing that.

I don't think that your Look has any compliance at all. My brother has one and he is slightly lighter than you. He uses those coverless carbon fiber saddles and breaks one about every six months. I can't get him to go to a stronger saddle because he's a weight weenie.

It's definitely stiff and I feel it when I hit a significant bump. The tires smooth out the ride and tame the typical road imperfections I encounter.

From memory, it isn't the inside width of the rim but the outside. The most aero rim/tire combination has something like a 1.5 mm wider tire than rim on each side. Assuming aero rims.

That's my understanding.