*Tour Aero Bike Tests*

[Roadbiker10]

Yeah, one should look at aero testing at most as a guideline. And the rider is still the biggest cause of drag on a bike. So getting into an aero position is more important than the frame aero as long as the frames are in the same ballpark. In a hypothetical case where you had an extremely aero frame that's 10 watts more aero than anything else in testing but it's impossible to have below 40 cm bars on it and you can't get as low as you'd want to on it and it's still a lot slower than some other frame where you can get into an aero position.

I agree about the bars.

I don't know if I agree on the second point though. Is there really a race bike which one can not get in a low enough position? Maybe it's just me, but I have never encountered this problem when looking to buy a bike. Or maybe I just don't ride with a big enough drop.

You can get a size smaller otherwise to get lower stack.

I would also argue that you don't need a huge drop to ride in an optimal aero position, which is with your forearms parallel to the ground.

[Lina]

Yeah, one should look at aero testing at most as a guideline. And the rider is still the biggest cause of drag on a bike. So getting into an aero position is more important than the frame aero as long as the frames are in the same ballpark. In a hypothetical case where you had an extremely aero frame that's 10 watts more aero than anything else in testing but it's impossible to have below 40 cm bars on it and you can't get as low as you'd want to on it and it's still a lot slower than some other frame where you can get into an aero position.

I agree about the bars.

I don't know if I agree on the second point though. Is there really a race bike which one can not get in a low enough position? Maybe it's just me, but I have never encountered this problem when looking to buy a bike. Or maybe I just don't ride with a big enough drop.

You can get a size smaller otherwise to get lower stack.

I would also argue that you don't need a huge drop to ride in an optimal aero position, which is with your forearms parallel to the ground.

It was more of a hypothetical situation, I can't really think of any aero bikes that have so high stacks that you couldn't get low enough.

What makes the Simplon far less versatile than the latest Venge or Madone?

Compared to those? Nothing. Compared to more conventional roadbikes? You can't switch to a seatpost with an exotic setback if you happen to need it, you can't really switch to bars with your favorite drop shape if you don't like the one on tap (however I happen to do like that "sectioned drop" on the Pride2, just not the rest of it), you can't - no, that's about it. All other supposed lack of versatility is wildly overstated.

Well, except maybe for use in unpredictable wind scenarios, because usually aero bikes looks work out so badly with low section wheels (particularly the bigger frame sizes) that I'd rather keep a dedicated bike for windy/unpredictable than just a dedicated set of low section wheels for the aero bike. What I mean with unpredictable wind is not so much days that might be gusty, but entire weeks with no opportunity to swap. If I need to select a bike ten days ahead there's no way I'll go deep section. Therefore, almost all my "flagship rides" are on the ancient aluminum 11s, not on the amazing aero wonder. I switched the aero to low section once, decided to never repeat, it was so ugly. Not even in a moonless night. I guess it would not be so bad for sizes M or smaller, but a 2XL aero frame on low section wheels - don't try this at home!

Oh I agree with you regarding the comparison to conventional/all rounder bikes. But the original comparison was explicitly to those bikes.

And what exactly is wrong with shallow wheels on an aero frame? I genuinely don't get why it looks so bad that you couldn't ride one. Surely everyone on the road understands the situation if you're out on a gusty day with an aero bike and shallow wheels and literally no sane person is going to judge you for it. Also with good well designed wheels you can ride deep wheels on pretty much any day you want to be riding outside. I live on a coast that's windy always and the shallowest set of wheels I have are 55s. Well technically I have a set of box section aluminium wheels but those have not been on a bike in years because there's simply no need for them.

[Roadbiker10]

I've had some pretty scary moments in windy conditions on my previous bike, a Reacto with 55 Visions. This year I'll be on an Addict RC with 65s, so we'll see how that goes.

It depends on how heavy you are. I'm 65kg so I've always had issues with the deep wheels in strong winds. Shifting your weight forwards in these situations helps.

The concept of shallower wheels in the front as for example Giant are doing is interesting if you want a compromise.

[Requiem84]

- Why compare aero bike 1 only to aero bike 2? Better comparison is a complete non-aero bike (let's say 5-6 years old) to a new aero bike. Difference will be much bigger than 3 watts.

As per old Tour figures, an old Emonda with Zipp 404s has a CdA of 0.1969 (with half mannequin), A Madone with same wheels 0.1746. A difference in CdA of 0.0223 (source: https://www.tour-magazin.de/uploads/tx_ ... 5ab73.jpeg).

If we plug a 0.0223 CdA difference in a calculator such as http://www.aeroweenie.com/calc.html , it gives approximately:
- a 8w difference at 30km/h,
- ca. 27w at 45km/h,
- ca. 55w at 60km/h.
etc.

The differences would possibly be even smaller than the above with a full rider on board.
The Emonda was as aero as a brick and equipped with round handlebars, today's bikes (probably even stuff like the Aethos) are more aero than that and anybody can use aero handlebars, so the difference would be even smaller.
So yeah, at 30km/h maybe most of us are sacrificing a handful of watts vs a full aero frame?

Not to mention that who knows exactly what happens when you're drafting, but definitely the savings are smaller.

Descending, sure (however - seems like everyone is hammering descents pedalling at VO2 max in this thread..). Sprinting, absolutely, give me all of those watts.
Regular riding and traditional road racing especially on hilly terrain? I'm not so sure.

Be my guest if you want to pick your frame based on these wind tunnel tests.

Personally I think 8watts at 30 km/h is quite significant, but that's just me of course.

On descending: if you do 70 km/h without pedalling, the cda difference of 0,02 will have much more impact of course given the relation between drag and speed.

[Rough]

https://ibb.co/4RJYxPg

Interesting results.

Is this result quite impressive for TCR as it has a round non-aero handlebar/cockpit?

Also as a general question: Is SRAM AXS considered less aero than Shimano Di2 because of the lever and derailleur shape?

[spartacus]

And what exactly is wrong with shallow wheels on an aero frame?

Doesn't look as cool. Here is my not very aero not very cool bike with 40mm wheels and a headlight. It's no simpleton pride 2 but I feel like it's a good all around compromise.

[cajer]

I think it's very unlikely the Pride 2 isn't significantly faster than the S5. On the most basic level, the amount of frame infill in the main triangle is huge. But whether that would lead to a 'significant' difference in the average rider's use case is questionable.

However the numbers say otherwise. There are older bikes with large amounts of infill that are slower.

[robeambro]

- Why compare aero bike 1 only to aero bike 2? Better comparison is a complete non-aero bike (let's say 5-6 years old) to a new aero bike. Difference will be much bigger than 3 watts.

As per old Tour figures, an old Emonda with Zipp 404s has a CdA of 0.1969 (with half mannequin), A Madone with same wheels 0.1746. A difference in CdA of 0.0223 (source: https://www.tour-magazin.de/uploads/tx_ ... 5ab73.jpeg).

If we plug a 0.0223 CdA difference in a calculator such as http://www.aeroweenie.com/calc.html , it gives approximately:
- a 8w difference at 30km/h,
- ca. 27w at 45km/h,
- ca. 55w at 60km/h.
etc.

The differences would possibly be even smaller than the above with a full rider on board.
The Emonda was as aero as a brick and equipped with round handlebars, today's bikes (probably even stuff like the Aethos) are more aero than that and anybody can use aero handlebars, so the difference would be even smaller.
So yeah, at 30km/h maybe most of us are sacrificing a handful of watts vs a full aero frame?

Not to mention that who knows exactly what happens when you're drafting, but definitely the savings are smaller.

Descending, sure (however - seems like everyone is hammering descents pedalling at VO2 max in this thread..). Sprinting, absolutely, give me all of those watts.
Regular riding and traditional road racing especially on hilly terrain? I'm not so sure.

Be my guest if you want to pick your frame based on these wind tunnel tests.

Personally I think 8watts at 30 km/h is quite significant, but that's just me of course.

On descending: if you do 70 km/h without pedalling, the cda difference of 0,02 will have much more impact of course given the relation between drag and speed.

Yes 8w at 30km/h can be significant but as I have explained:

- it's 8w with half a mannequin, we don't know whether it holds fully with a pedalling rider on board

- it's between one of the fastest aero frames (Madone rim) vs one of the slowest frames, if not the slowest, Tour ever tested, so 8w is more like a "worst case scenario". Most of us today will pick between a semi-aero and a full-aero frame.

- frames aside, most possibly the 8w can be halved by fitting aero handlebars on the "slow" bike (most likely, Madone was tested with aero bars and Emonda with round bars)

So in the real world differences could be far smaller than 8w.

I am not an aero denier, i love aero. I just want people to acknowledge that the frame is by far not giving them as sharp of an edge as they think. At least for regular riding - as I said, sprinting is different.

[Lina]

I just want people to acknowledge that the frame is by far not giving them as sharp of an edge as they think. At least for regular riding - as I said, sprinting is different.

This is what people need to understand. Frame is probably the last place you should be upgrading in terms of aero. Wheels, cockpit, clothing, helmet, position on the bike. All a lot easier, and cheaper to upgrade and most probably have a bigger effect than upgrading your frame to more aero. Now if you're looking to buy a new bike it might make sense to at least make sure it doesn't have the aero properties of a brick. But don't worry over single digit differences in wind tunnel tests done at 45 km/h. Especially if the "slower" bike comes with round bars and/or shallower wheels.

[usr]

And what exactly is wrong with shallow wheels on an aero frame? I genuinely don't get why it looks so bad that you couldn't ride one. Surely everyone on the road understands the situation if you're out on a gusty day with an aero bike and shallow wheels and literally no sane person is going to judge you for it.

Then call me insane, because while I hope that I would not judge others, I certainly do judge me. If I didn't, I'd ride looking like a hobo, complete with a matching bike that looks like I found it on the side of the in the Lance era. How did I know? Because that's basically off-bike me (There might be an element of compensation hidden somewhere between Castelli, Canyon and Campagnolo?)

And, yeah, shallow wheels on an aero frame look quite alright. If it's not a particularly large frame. Up to "catalog size" they almost look better, because the perceptually light wheels emphasize the visual boldness of frame. But in the larger sizes, the deep sections of the frame just balance out the length of the tubes, the frame just looks well-proportioned in a way frames that size usually don't. Until you put on non-deep wheels, then it just looks off. The wheels look like placeholders not intended to riding.

Also with good well designed wheels you can ride deep wheels on pretty much any day you want to be riding outside. I live on a coast that's windy always and the shallowest set of wheels I have are 55s. Well technically I have a set of box section aluminium wheels but those have not been on a bike in years because there's simply no need for them.

Yeah, it's been a while since I last felt "this is really too much" on 60s. On a typical home ride I'd rather adapt the route than change wheels/bike and when the wind is too strong for that I'd probably stay home completely. But when my last opportunity to switch bikes is on Thursday and I still have to ride that bike Saturday after the next, then no weather forecast in the world will be able to promise me absence of storms convincingly enough for me to take the deep wheels. Particularly if that Saturday has scheduled as many long, fast descends as I can climb (like all the days in between tend to have - and I wouldn't mind the deep wheels at all most of those days, if the choice was available in the morning but it's not). I've had wind barely ridable with Zondas on occasions like that, no way I'd risk taking the 60s instead.

[Hexsense]

I don't know if I agree on the second point though. Is there really a race bike which one can not get in a low enough position? Maybe it's just me, but I have never encountered this problem when looking to buy a bike. Or maybe I just don't ride with a big enough drop.

You can get a size smaller otherwise to get lower stack.

Yes. I do. My main issue for the aero bike fit is the required stem is not 17 degree.

First, my normal bike size is 48-50cm. Going down in size usually cause 2 out of 3 problem:
1) need 120-130mm stem on size 44-47mm frame... On some bike, availability of 130mm is an issue. Extra long stem on tiny size bike is also wrong fashionally.
and could be either..
2) severe toe overlap and unstable handling due to short wheel base (Allez Sprint approach)
or
3) headtube angle slacken too much without proper fork offset to bring trail value back to proper value (chinese open mold approach)

So, my best fit usually require -17 degree stem slammed. Then, I can use size 48-52cm bike and 110-120mm stem length.
If the bike require proprietary stem and that stem is slacker than 17 degree or require tall transition spacer, then I have no choice but to downsize the bike and use longer stem to get it low enough.

Specifically, I can use 532mm stack if the stem is -17 degree with no mendatory spacer required, and headset cap is less than 12mm tall.
I require 521mm stack if the stem is -12 degree.
508mm stack if the stem is -6 degree and no spacer required. This start to get less common.
Sub 500mm stack if that -6 degree stem also require a sizable mendatory spacers... That's normally not an option.

[Lina]

I've never not had a road bike without toe overlap. Can someone explain why it's supposed to be such a problem?

[Hexsense]

It's not the toe overlap that is the problem. But rather, front heavy-ish weight balance that come with bike that has it. It's not that front carry more weight than the back, just that more weight in the back is easier to handle.

I never knew how a properly balanced bike would handle until I switched from Allez Sprint size 49 to SuperSix Evo size 48.
Allez Sprint has 566mm front center with about 1cm toe overlap. Supersix Evo has 588mm front center with load of toe clearance, more than front center number suggest, because more fork offset move wheel more away from my toe as I turn.
Both have about the same reach and both use 120mm stem. My cornering improve dramatically with the lengthening of front center. I no longer have to scoot back before hard corner anymore. I imagine Allez Sprint 49 with shorter stem weight balance would also be okay.

PS. below are example 3 bikes that has similar stack and reach but short, medium, long front center length and wheelbase in size 51-52
https://geometrygeeks.bike/compare/spec ... x-2020-51/

[Roadbiker10]

It's not the toe overlap that is the problem. But rather, front heavy-ish weight balance that come with bike that has it. It's not that front carry more weight than the back, just that more weight in the back is easier to handle.

I never knew how a properly balanced bike would handle until I switched from Allez Sprint size 49 to SuperSix Evo size 48.
Allez Sprint has 566mm front center with about 1cm toe overlap. Supersix Evo has 588mm front center with load of toe clearance, more than front center number suggest, because more fork offset move wheel more away from my toe as I turn.
Both have about the same reach and both use 120mm stem. My cornering improve dramatically with the lengthening of front center. I no longer have to scoot back before hard corner anymore. I imagine Allez Sprint 49 with shorter stem weight balance would also be okay.

PS. below are example 3 bikes that has similar stack and reach but short, medium, long front center length and wheelbase in size 51-52
https://geometrygeeks.bike/compare/spec ... x-2020-51/

I never even thought of that. After I read your post I was worried that my new Addict RC in 54 which is a size too small for me, might have that issue.

It doesn't say anywhere for the Addict what the front centre is. But from what I gather, on other bikes. Wheelbase minus chainstay length + 1cm gets you the front centre figure. So I realised the Scott pretty much has the same front centre as my old bike, which had a 56cm top tube. The Scott in 54 has a 55cm top tube and the same reach as my old bike. So the front centre on the Addict RC in 54 is 592 from what I understand. The Venge has 591 on a 56.

But yeah, that's something to consider on smaller bikes.

[FlatlandClimber]

Not as aero as it looks:


Stupid wheel choice though.