*Tour Aero Bike Tests*

[Nickldn]

Look, what we actually need are better road surfaces. In the UK at least road surface quality has got a lot worse since Covid, with no signs of improvement. I'm guessing it's much the same in the USA and in much of Europe too.

This is unwarranted assumption. Amazingly enough, government investment in basic infrastructure is not equally bad everywhere. I ride regularly on the Mediterranean coast of Spain, and the road maintenance there is amazing. Swizerland is also quite good, despite the mountains, snow, etc. UK is completely atrocious, by contrast, to a point where I wonder whether I should just be riding a gravel bike here all the time.

But I do agree that road surface quality (or lack thereof) do drive a lot of this debate. 25mm tyres at 90 psi are totally fine on super smooth surfaces.

Absolutely agree there are some bright spots in Europe and am very glad to hear that parts of Spain has smooth roads. I wish it was like that everywhere, as to me 25c @ 90psi provides great responsiveness and road feel. I was out today on my old rim brake Propel with 24.5mm actual width Vittoria Corsa tubs, great fun, but constantly had to dodge the potholes in Sunbury-upon-Thames.

[Jaisen]

The "problem" with suspension is that it always adds weight. With the current weight limit it's difficult to see many brands making a bike that's for example 8 - 9 kg in race setup with top shelf parts. Even when it would have minimal impact on flat races/stages and make the bike faster.

Not only does it add weight it also impacts the handling performance of the bike. Specialized's future shock system is rather interesting however since you can lock out the suspension at the turn of a knob. So you can get the smooth ride when you need it and disable the dampening when called for. But one major downside is their system precludes the ability of internally routing the cables, which then introduces some aerodynamic drag and is less aesthetic. I haven't seen any bike suspension system that doesn't have some compromises. It is curious though that for all other modes of transport, we rely heavily on suspensions to improve performance and to optimize tire performance, but for bikes we require the tires to pull double duty acting as our only means of dampening.

[Jaisen]

The need for more comfort due to terrible road surfaces is really what is driving the adoption of 28c+ tyres, not the desire for better RR. Better RR requires using high tyre pressures, even with wider tyres, which negates the added comfort aspect. So if you run wider tyres you still have to pick between better RR to offset the aero penalty, or more comfort. There is no free lunch as far as I can tell.

I don't think this is accurate. At the World Tour comfort is the least important variable. The performance of the equipment is the #1 priority. Pretty much all of the teams are now riding 28mm tires, some like UAE are riding very wide internal rims (25mm) on 28mm tires, which is effectively the same as riding 30mm tires on normal 21mm internal rims. So as far as the world tour is concerned, 28s and 30s are the fastest tested tires/equipment. For races like Paris-Roubaix, they are even running 32mm tires that can measure out close to 34mm when installed on the rims.

[cajer]

At the end of the day, we buy things a particpate in these threads to obsess over performance numbers. So I think every marginal watt matters, if it doesn't then there's no point in joining these conversations.

Also I don't see what the point of a wider tire beyond 25mm (just due to lack of good 23mm tire availbility these days). As it's been shown that larger tires are not more comfortable nor do they show better rolling resistance assuming same casing tension, I don't see the point of going wider unless you're on mixed surfaces.

It's been shown that wider tires aren't more comfortable? Cmon now, your taking the piss here.

If you keep the same casing tension then the initial spring rate is the same when loaded with your weight. If your road is decently and not very bumpy then you'll only have small increases in pressure from deformation due to bumps. So the spring rate of the smaller tire will remain similar to the larger tire. Of course this doesn't apply if you're heavy and don't use tubeless due to the need to keep smaller tires at high pressures to avoid pinch flats.

Basically with small perturbations the less progressive nature of smaller tires doesn't matter. However with larger things like pot holes, I'm doubtful going from 28-30 will make much of a difference due to the small change in volume. This is the same effect going on with all the air volume/progressivity tuning that is done on mtb air suspension.

Going from 28->30 (often just 30.5mm WAM to 31.5mm WAM) is going to be relatively minor, but you were promoting 23mm and 25mm just a post earlier. At the same casing tension, a 28mm WAM tire can absorb just about twice the impact energy as a 25mm WAM tire before bottoming out. From personal experience, almost all my DNFs in the last 4 years were when I elected to run nominal 25mm tires. All the flats were from hitting potholes at race pace.

I'm willing to give up 1.5 watts to aero drag if I can gain them back from comfort and real-world Crr gains...and reducing my chances of flatting out of contention.

I would agree with you there, if I had acutally flatted from an impact in the last 7-8 years. At those rates, I'm more than willing to take a gamble for 1-2W.

I'm entirely unconvinced that going to wider tires (if you're able to run low enough presses on skinnier tires + have the same tire construction) is any faster or more comfortable if your road surface is decent.

For refrence I'm light enough to run 75/75 psi on 23mm GP5000 (21mm internal width) and 25mm GP5000 (23mm internal width) front/rear tires. I also live in the San Fransico bay area with very nice roads for riding.

[wheelsONfire]

The "problem" with suspension is that it always adds weight. With the current weight limit it's difficult to see many brands making a bike that's for example 8 - 9 kg in race setup with top shelf parts. Even when it would have minimal impact on flat races/stages and make the bike faster.

You have to scratch your "old" ideas of what suspension is. It could be a lamella design made from carbon. I don't think it would add so much, but ofcourse it would weigh more. Imagine it would work as a "fatter" tire not suffer from what some refer to as suspension bobbing. I think it would be a reasonable evolution. This aero yada yada can't progress much more. Soon we are nitpicking down to ridicule placebo gains when it comes to aero.

[Jaisen]

The "problem" with suspension is that it always adds weight. With the current weight limit it's difficult to see many brands making a bike that's for example 8 - 9 kg in race setup with top shelf parts. Even when it would have minimal impact on flat races/stages and make the bike faster.

You have to scratch your "old" ideas of what suspension is. It could be a lamella design made from carbon. I don't think it would add so much, but ofcourse it would weigh more. Imagine it would work as a "fatter" tire not suffer from what some refer to as suspension bobbing. I think it would be a reasonable evolution. This aero yada yada can't progress much more. Soon we are nitpicking down to ridicule placebo gains when it comes to aero.

Josh from Silca did a recent chat with Mark Cote, formally with Specialized and one of the main reasons they developed their wind tunnel in the first place. During their discussion it came up that aero tech has pretty much hit peak. Sure there might be a few little refinements here and there in the future but all the low hanging fruit is long gone. Before the aero phase, the big buzz was weight. Mark Cote mentioned the new area of peak interest going forward is looking into thermal optimizations. We're starting to see more and more emphasis on it, from the slushies all the teams are now downing, to the cooling vests, to better clothing materials, helmets, shoes, etc.

[spartacus]

In my experience even on great roads 25mm tires are more prone to being damaged than larger tires by rocks or debris. Here it is possible to ride over 30mph for minutes at a time and at those speeds on a 25c tire things that are hard to see can destroy the tire easily, not to mention the drainage dips around intersections, going into crowned roads etc, for me even with "nice roads" having more cushion to send it is a big advantage.

Also IME wide tires on narrow rims are a different thing than tires mounted on wide wheels and rims. It feels like they roll much faster when the sidewalls are not bulbed.

[TobinHatesYou]

I would agree with you there, if I had acutally flatted from an impact in the last 7-8 years. At those rates, I'm more than willing to take a gamble for 1-2W.

I'm entirely unconvinced that going to wider tires (if you're able to run low enough presses on skinnier tires + have the same tire construction) is any faster or more comfortable if your road surface is decent.

For refrence I'm light enough to run 75/75 psi on 23mm GP5000 (21mm internal width) and 25mm GP5000 (23mm internal width) front/rear tires. I also live in the San Fransico bay area with very nice roads for riding.

Most of the Bay Area’s ”best” riding roads are chip seal or slurry seal. Many have potholes and longitudinal cracks. Some roads just haven’t been repaved in decades. Just about everyone who races or rides fast in the Bay Area is on nominal 28mm minimum these days. Just join a Nooner or TMR or Spectrum and ask.

I’m literally the aero is everything guy here and I run 31mm WAM tires.

[twoangstroms]

Even as a smaller-than-Tobinhatesyou guy, I've also flatted out of races due to impact punctures, and can attest that "comfort" should more realistically be called "reduction in fatigue from repeated jackhammer hits" in NorCal races and rides. (Side note: we talked about Copperopolis and Low Gap gravel being on the same weekend, and decided Low Gap would be a smoother experience.)

Also, honest question: Aren't those tests numbers for a bike (w/ or w/o rider dummy) in isolation? If you're racing, even in a small break, you'll likely benefit from more security, better rolling resistance, and handling, but less so from the marginal aero gains?

[spdntrxi]

Also, honest question: Aren't those tests numbers for a bike (w/ or w/o rider dummy) in isolation? If you're racing, even in a small break, you'll likely benefit from more security, better rolling resistance, and handling, but less so from the marginal aero gains?

dummy is half- torso

[pmprego]

Also, honest question: Aren't those tests numbers for a bike (w/ or w/o rider dummy) in isolation? If you're racing, even in a small break, you'll likely benefit from more security, better rolling resistance, and handling, but less so from the marginal aero gains?

dummy is half- torso

I read his question as to the usual claims "x seconds over 40km" - how often are you in such situation?

If in a small break you rotate with someone else, then it is no longer 40km but maybe 10km (4 people break) then it is not x seconds but x/4. I read it in this way

[GrassQ]

In Chris Millers youtube interview Tour Magazines Robert Kühnen talk a little about bikes/wheels aeroprofile and choosen surrounding wind (and distribution).

I understood that if you want to know exact how aero a bike or wheel is, you should compare products aeroprofile/aerocurve to each other in different yaw angles, becauce "one number" is valid only in certain and choosen conditions (but probably also gives a good ballbark number in variable conditions)
Tour use 10 kmh average wind and Weibull distribution. If they would use lower or higher average wind, results likely be differend at least a little. In lower wind differences should be smaller, because the sailing effect is bigger in higher wind/high yaw angles especially in wheels

I havent seen that Tour had published aerocurves recently. I remember 60 mm wheelstest 2022 and some aero-lightweight comparison maybe from 2018 where you can see those curves.

[spartacus]

I sent an email to Swiss side a while back as well as another wheel builder asking some questions about the sailing effect and it is definitely a real but not always reliable or predictable thing that can happen (in the sense of real world conditions that is, in a lab it can be reproduced obviously).

I think I know the answer to this but I'm wondering if any of the wheel or entire bike aero tests take into account the sailing effect.

What specifically I'm wondering is about quantifiable differences in performance under side, tail, high yaw, etc... conditions that would generate thrust.

Something that made me think about this is arguments for rear disc wheels on slow twitch which seem to indicate potential aero "gains" well beyond what would be found in a "traditional aero test".

Furthermore there have been comments that for example the allez sprint is supposed to be "as aero" as the first gen venge but it has been widely purported that the venge "sails better" and in spite of claims assumed at low yaws; will perform better in general. This is just one example.

What I'm getting at is how much these aero rankings actually represent the performance of the bike in the real world.

Another thing I think about is the additive effect of forward and wind speed, which makes me wonder if aero bikes are more effective than claimed since effective wind speed can often be higher than indicated speed on the computer.

lastly I wonder about is coasting speed downhill. Because of the nonlinear nature of drag it makes me wonder how much of a difference happens when we are talking pure coasting at speeds over 40mph when the theoretical drag differences between aero and non aero bikes could be 100w or more...

[justkeepedaling]

I would agree with you there, if I had acutally flatted from an impact in the last 7-8 years. At those rates, I'm more than willing to take a gamble for 1-2W.

I'm entirely unconvinced that going to wider tires (if you're able to run low enough presses on skinnier tires + have the same tire construction) is any faster or more comfortable if your road surface is decent.

For refrence I'm light enough to run 75/75 psi on 23mm GP5000 (21mm internal width) and 25mm GP5000 (23mm internal width) front/rear tires. I also live in the San Fransico bay area with very nice roads for riding.

Most of the Bay Area’s ”best” riding roads are chip seal or slurry seal. Many have potholes and longitudinal cracks. Some roads just haven’t been repaved in decades. Just about everyone who races or rides fast in the Bay Area is on nominal 28mm minimum these days. Just join a Nooner or TMR or Spectrum and ask.

I’m literally the aero is everything guy here and I run 31mm WAM tires.

Canada is pretty much perfect road to me. Come to Utah and I'll show you shit roads

[justkeepedaling]

I sent an email to Swiss side a while back as well as another wheel builder asking some questions about the sailing effect and it is definitely a real but not always reliable or predictable thing that can happen (in the sense of real world conditions that is, in a lab it can be reproduced obviously).

I think I know the answer to this but I'm wondering if any of the wheel or entire bike aero tests take into account the sailing effect.

What specifically I'm wondering is about quantifiable differences in performance under side, tail, high yaw, etc... conditions that would generate thrust.

Something that made me think about this is arguments for rear disc wheels on slow twitch which seem to indicate potential aero "gains" well beyond what would be found in a "traditional aero test".

Furthermore there have been comments that for example the allez sprint is supposed to be "as aero" as the first gen venge but it has been widely purported that the venge "sails better" and in spite of claims assumed at low yaws; will perform better in general. This is just one example.

What I'm getting at is how much these aero rankings actually represent the performance of the bike in the real world.

Another thing I think about is the additive effect of forward and wind speed, which makes me wonder if aero bikes are more effective than claimed since effective wind speed can often be higher than indicated speed on the computer.

lastly I wonder about is coasting speed downhill. Because of the nonlinear nature of drag it makes me wonder how much of a difference happens when we are talking pure coasting at speeds over 40mph when the theoretical drag differences between aero and non aero bikes could be 100w or more...

All of them do. Take a look at the drag plot of a bike with rider on it. They all drop drag going out to higher yaw. Additive effect of true freestream velocity, yes, that is correct. The drag is higher. That said, from the math, the power to maintain velocity for a 40 kph speed vs a combined wind plus is higher, it's somewhere in between