*Tour Aero Bike Tests*

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BigBoyND
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Joined: Mon May 31, 2021 1:51 am
Location: Berlin, DE

by BigBoyND

Don't they test with two standard bottles already? I thought they did. And that's a good thing, I agree.

W/r/t bars, if it's a non-proprietary setup (including Cannondle, Spec, and Trek which allow for a standard stem without any modification) then they should use the same bars as a secondary measurement like the Zipp 404 test. Only bikes with truly proprietary bars wouldn't' benefit from this test. Wheels and bars are swapped by a lot of us.

If I want to go for an aero build. I want an aero frame, aero wheels, and aero cockpit. Testing different bikes with different components won't tell me which frame is aero.

A simple analogy is the same scenario for WW comparisons. Weighing complete bikes would make you think that the SuperSix is heavier than a Venge, but the difference comes from the pig of a SAVE cockpit which is easily changed.

rudye9mr
Posts: 498
Joined: Wed May 01, 2019 12:01 pm

by rudye9mr

Cool with it as is for a general guide.

i'm not averaging 45kmph in any case so use the results as a guide to effeciency...

in any event, so many small things can affect aero - loose clothing, cable out in the wind, one's own CdA etc.

by Weenie


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fa63
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Location: Atlanta, GA, US

by fa63

rudye9mr wrote:Cool with it as is for a general guide.

i'm not averaging 45kmph in any case so use the results as a guide to effeciency...

in any event, so many small things can affect aero - loose clothing, cable out in the wind, one's own CdA etc.
It is easy to scale to speeds that you ride at. Power is proportional to velocity cubed so for 30 kph, you would be looking at a scaling factor of (30/45)^3 which is about 0.3. That means 20W at 45 kph would be 6W at 30 kph.

BigBoyND
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by BigBoyND

Cubed or squared?

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fa63
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Location: Atlanta, GA, US

by fa63

Power is cubed, drag is squared.

BigBoyND
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Location: Berlin, DE

by BigBoyND

You're right.... I need to go back to school...

IanisCercariolo
Posts: 70
Joined: Sat Jun 06, 2020 9:58 am
Location: Vaud, Switzerland

by IanisCercariolo

fa63 wrote:
Mon Nov 15, 2021 3:37 am
Power is cubed, drag is squared.
Could you explain me the reasoning behind this statement ?

My understanding is the following, if we consider two different drags at the same speed :
- Power from the rider to the cranks equals Torque x Rotation speed
- Considering the same rider cadency and the same development, any increase in drag translates to a proportional increase in torque in the cranks
- So, any increase in drag (let's say +10%) results in the same power increase for the rider

Now, if we extrapolate a drag value to another speed :
- Power approximately equals (rho/2).Cd.A.speed^2
- Any relative speed shift results in the squared value for power (+33% speed = +100% power, etc.)

So, to me, power is squared and drag is linear, but I may be missing something, thanks in advance !

mgrl
Posts: 340
Joined: Wed Nov 25, 2020 12:49 am

by mgrl

IanisCercariolo wrote:
Tue Nov 23, 2021 8:16 am
fa63 wrote:
Mon Nov 15, 2021 3:37 am
Power is cubed, drag is squared.
- Power approximately equals (rho/2).Cd.A.speed^2

So, to me, power is squared and drag is linear, but I may be missing something, thanks in advance !
The error is here - that's the expression for aerodynamic drag not for the power required to overcome it. So the drag is squared, and then P = F.v which is where you pick up the cubic v from.

IanisCercariolo
Posts: 70
Joined: Sat Jun 06, 2020 9:58 am
Location: Vaud, Switzerland

by IanisCercariolo

mgrl wrote:
Tue Nov 23, 2021 10:16 am
IanisCercariolo wrote:
Tue Nov 23, 2021 8:16 am
fa63 wrote:
Mon Nov 15, 2021 3:37 am
Power is cubed, drag is squared.
- Power approximately equals (rho/2).Cd.A.speed^2

So, to me, power is squared and drag is linear, but I may be missing something, thanks in advance !
The error is here - that's the expression for aerodynamic drag not for the power required to overcome it. So the drag is squared, and then P = F.v which is where you pick up the cubic v from.
Thanks !

req110
Posts: 866
Joined: Thu Nov 22, 2018 10:23 am

by req110

Guys, do we have available some tests for

BMC Team machine SLR 01
Factor Ostro Vam
Scott Foil 2022

I am considering to build one of these bikes... (yes, i couldn't live without road bike for more than week)
SW SL8 RTP 56cm @ 9270 / CLX II / CS OSPW / CEMA BB
S Epic 8 L @ XX T-Type / Berg Ratheberg 30 / Quarq / Fox Transfer SL 100mm / 3p

FlatlandClimber
Posts: 2491
Joined: Tue Mar 31, 2020 3:37 pm

by FlatlandClimber

Image

It may be the fastest bike, but man is the Storck ugly.
Cervelo P5 Disc (2021) 9.1kg
Factor Ostro Gravel (2023) 8.0kg
S-Works SL8 (2023) 6.3kg

*weights are race ready, size 58/L.
Sold: Venge, S5 Disc, Roubaix Team, Open WI.DE, Émonda, Shiv TT, Crux, Aethos, SL7

Eterna7m
Posts: 377
Joined: Thu Jan 07, 2021 11:25 pm

by Eterna7m

FlatlandClimber wrote:
Fri Jan 14, 2022 11:48 am
Image

It may be the fastest bike, but man is the Storck ugly.
Which issue is that? Are these the only bikes tested?

FlatlandClimber
Posts: 2491
Joined: Tue Mar 31, 2020 3:37 pm

by FlatlandClimber

Most recent issue 2/22 - these are the fastest bikes tested. Only 2 bikes they tested were Simplon and Storck in this issue.
Cervelo P5 Disc (2021) 9.1kg
Factor Ostro Gravel (2023) 8.0kg
S-Works SL8 (2023) 6.3kg

*weights are race ready, size 58/L.
Sold: Venge, S5 Disc, Roubaix Team, Open WI.DE, Émonda, Shiv TT, Crux, Aethos, SL7

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cyclespeed
Posts: 1120
Joined: Mon Jun 06, 2016 8:45 am

by cyclespeed

req110 wrote:
Wed Jan 12, 2022 9:44 am
Guys, do we have available some tests for

BMC Team machine SLR 01
Factor Ostro Vam
Scott Foil 2022

I am considering to build one of these bikes... (yes, i couldn't live without road bike for more than week)
Would be keen to see results for Ostro VAM.

Or do you mean the One? Personally i think the Ostro is very close to the One aero wise, but a sh!t ton lighter.

StiffWeenies
Posts: 613
Joined: Sun Feb 28, 2021 3:39 pm

by StiffWeenies

FlatlandClimber wrote:
Fri Jan 14, 2022 11:48 am
Image

It may be the fastest bike, but man is the Storck ugly.
Interesting how a rebranded Pardus Spark EVO with a revised fork is among the world beaters in this test

by Weenie


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