Aero bikes and the Pro peloton...

Discuss light weight issues concerning road bikes & parts.
IchDien
Posts: 533
Joined: Mon Nov 05, 2012 12:23 am
Location: Veneto

by IchDien

All this begs the question; if the cockpit is such high drag are we not due for a redisgn of the levers and brake hoods fairly soon? Chasing a few watts at most but surely all "marginal gains"? Or would this simply be trying to re-design the wheel in bicycle tech?

IchDien
Posts: 533
Joined: Mon Nov 05, 2012 12:23 am
Location: Veneto

by IchDien

IchDien wrote:
Fri Dec 07, 2018 8:08 am
All this begs the question; if the cockpit is such high drag are we not due for a redisgn of the levers and brake hoods fairly soon? Chasing a few watts at most but surely all "marginal gains"?

Or would this simply be trying to re-design the wheel in bicycle tech?

by Weenie


parajba
Posts: 613
Joined: Tue Oct 28, 2008 9:00 pm
Location: London, United Kingdom

by parajba

IchDien wrote:
Fri Dec 07, 2018 8:10 am
IchDien wrote:
Fri Dec 07, 2018 8:08 am
All this begs the question; if the cockpit is such high drag are we not due for a redisgn of the levers and brake hoods fairly soon? Chasing a few watts at most but surely all "marginal gains"?

Or would this simply be trying to re-design the wheel in bicycle tech?
I think the hoods are pretty much hidden behind our hands..and the levers look already pretty slick to me...and their primary purpose is safety and being ergonomic...

robeambro
Posts: 616
Joined: Sat Jul 07, 2018 6:21 pm

by robeambro

Lelandjt wrote:
Fri Dec 07, 2018 12:55 am
robeambro wrote:
Thu Dec 06, 2018 7:24 pm
Matt28NJ wrote:
Thu Dec 06, 2018 6:37 pm
parajba wrote:
Thu Dec 06, 2018 2:02 pm
Lots of interesting points here.

Does anyone know how little or big is the drag of the frame/wheels compared to the rider?
Cervelo's take:
...through CFD Cervélo studied the impacts of individual bike elements on the total aero drag of a road bike with its rider. The numbers revealed key elements that had major effects, and these were items where they dove into more deeply to minimize drag:
• 1% – seatpost
• 2% – rear brake
• 3% – front brakw
• 5% – rear wheel
• 9% – drivetrain
• 9% – bottle
• 9% – fork
• 16% – frame
• 16% – front wheel
• 30% – handlebar
Thanks!

As I remembered, handlebar matters more than the frame. (Which is definitely something not many pay attention to.. Weirdly, it is very much likely that a "traditional" round-tube bike with aero handlebars and integrated cables would be more aero than an aero frame with a traditional handlebar and cables lying around.

That being said, those %'s may be deceiving, cause they amount to the 100% of the bike-only drag. Which in turn is small compared to the rider's drag.
You're forgetting that every part of the frame can be made more aero. With the handlebar most of it is the same between aero and regular. To reach your conclusion they'd only be considering the flats of the handlebar.
Not quite sure what you mean - anyway I wasn't giving any conclusion, maybe I should've said "possible" rather than "likely", but still.

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taodemon
Posts: 96
Joined: Tue Aug 29, 2017 2:04 pm
Location: Massachusetts

by taodemon

robeambro wrote:
Thu Dec 06, 2018 5:21 pm
Same! Science (and even geometry for me) says SL6 .. But that Venge, man ...
(and also partly, I think the SL6 doesn't look good in black, and I can't bring myself to like any of the other paintjobs)
Have you seen the new paint jobs for 2019? Pretty much everything that was available as disc only before is now also available in rim if that was a consideration(it was for me). That means if I had been a bit more patient I would have finally gotten the chameleon frame I've been dreaming of for years. Ended up going with the black womens frame.

Also depends where you ride. If its completely flat venge would be a no brainer.

robeambro
Posts: 616
Joined: Sat Jul 07, 2018 6:21 pm

by robeambro

taodemon wrote:
Fri Dec 07, 2018 3:21 pm
robeambro wrote:
Thu Dec 06, 2018 5:21 pm
Same! Science (and even geometry for me) says SL6 .. But that Venge, man ...
(and also partly, I think the SL6 doesn't look good in black, and I can't bring myself to like any of the other paintjobs)
Have you seen the new paint jobs for 2019? Pretty much everything that was available as disc only before is now also available in rim if that was a consideration(it was for me). That means if I had been a bit more patient I would have finally gotten the chameleon frame I've been dreaming of for years. Ended up going with the black womens frame.
I have, and the chameleon seems nice, I'm only afraid that it would look too "purple" in real life. I would like to see it.. But we're OT :mrgreen:

Now, to go back in topic, I think that for example the new Izalco Max is how aero bikes for the pro peloton should be. It may make a great GC contender bike.
It has most of the desirable aero features, including dropped seatstays, fully internal cabling and aero cockpit. It's not a feather but I reckon with tubulars may be very close to the UCI limit.

The only problem is that the white colourway is a bit out of my price range :mrgreen:

darnellrm
Posts: 242
Joined: Thu Sep 10, 2009 1:06 pm
Location: NC, USA

by darnellrm

cunn1n9 wrote:
Thu Dec 06, 2018 11:57 am
If you do a thought experiment you can see that for all intents and purposes lateral stiffness of the frame simply is irrelevant.

Think about the fact that the component of the force that causes the lateral deflection exists whether the frame is infinitely stiff or a “noodle”. This force is due to the fact that my feet apply force that is offset from the centre line of the bike and so creates a torque around (or about) that centre line that creates the lateral movement/flex in the frame. Now the actual distance the frame flexes is determined by its lateral stiffness. However the force that causes this flex has already occurred and the fact the the frame resists it either more or less happens after the fact of the force being applied. The key thing to understand is that this off centre force component does not contribute anything whatsoever to forward propulsion of the bike. In fact crank based power meters like Stages, Pioneer, Shimano, Infocrank etc. as well as pedal based power meters like Vector, Assioma, Powertap, etc identify this off centre component of the force vector for the express purpose of deleting it from the power calculation. If they didn’t the power reading calculation based on crank flex would be too high. (Some power meters like Infocrank actually orient their strain guages so that this off centre force is eliminated at the actual strain guage. They have a whitepaper with diagrams and explanations of this that if you read you will get a better explanation than what I have tried to provide above).

So it makes no difference whether the bike flexes laterally 0mm or 10mm due to the off centre force component. The force causing this flex doesn’t contribute anything to forward propulsion and is expended before the frame flexes. So the frame being stiffer doesn’t save anything at all. Nor does it flexing back return any useful forward propulsion force either.

There is however a difference in feel though and our minds will perhaps in some peoples experience interpret one as feeling faster than the other but I guarantee that if you pedal exactly the same way in two different lateral stiffness bikes your acceleration would be identical as long as all other variables (weight, aero) were the same.

(However if I was on a vertically compliant frame where the BB actually flexed downwards as I exerted force into the pedals WOULD deduct from the force being applied as the movement is in the same direction as the forward propulsion force. This would be similar to if I used soft soled shoes and as I pushed down I compressed the sole of the shoe. This compression absorbs useful force which is lost as it is in the same direction as the useful force.
However as this vertical flex movement is actually very small it is probably not worth worrying about.)


Sent from my iPhone using Tapatalk
The problem with your simplistic theory is that as the frame flexes, the proportion of pedaling force in the horizontal plane increases due to the force being applied at the angle of the bottom bracket defelction. The more the bottom bracket flexes the greater the portion of pedaling force that is directed into the horizontal direction.

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Lelandjt
Posts: 526
Joined: Tue Jan 19, 2016 7:10 am

by Lelandjt

robeambro wrote:
Fri Dec 07, 2018 1:08 pm
Lelandjt wrote:
Fri Dec 07, 2018 12:55 am
robeambro wrote:
Thu Dec 06, 2018 7:24 pm
Matt28NJ wrote:
Thu Dec 06, 2018 6:37 pm


Cervelo's take:
...through CFD Cervélo studied the impacts of individual bike elements on the total aero drag of a road bike with its rider. The numbers revealed key elements that had major effects, and these were items where they dove into more deeply to minimize drag:
• 1% – seatpost
• 2% – rear brake
• 3% – front brakw
• 5% – rear wheel
• 9% – drivetrain
• 9% – bottle
• 9% – fork
• 16% – frame
• 16% – front wheel
• 30% – handlebar
Thanks!

As I remembered, handlebar matters more than the frame. (Which is definitely something not many pay attention to.. Weirdly, it is very much likely that a "traditional" round-tube bike with aero handlebars and integrated cables would be more aero than an aero frame with a traditional handlebar and cables lying around.

That being said, those %'s may be deceiving, cause they amount to the 100% of the bike-only drag. Which in turn is small compared to the rider's drag.
You're forgetting that every part of the frame can be made more aero. With the handlebar most of it is the same between aero and regular. To reach your conclusion they'd only be considering the flats of the handlebar.
Not quite sure what you mean - anyway I wasn't giving any conclusion, maybe I should've said "possible" rather than "likely", but still.
I think Cervelo is saying the entire handlebar, maybe even including the levers and tape, contributes to 30% of a bike's drag. Switching from a regular bar to an aero one only changes the shape and amount of drag that the flat part of the bar contributes. Although the frame contributes only 16%, when switching between regular and aero the entire frame can be made more slippery. So, my thinking is the difference between regular and aero frames could be the same or even more than the difference between regular and aero bars, even though a quick look at their data would make you think otherwise.

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Lelandjt
Posts: 526
Joined: Tue Jan 19, 2016 7:10 am

by Lelandjt

Lelandjt wrote:
Thu Dec 06, 2018 8:58 am
Isn't the Tarmac laterally and torsionally stiffer than the Venge?
No one answered before so I'm asking again and we can broaden this to include everyone's climbing bike vs aero bike. Since almost everything can be built to 6.8kg is the difference in climbing feel* that aero bikes are flexier when you're climbing out of the saddle?

*I'm not saying there's a difference. I think my 6.6kg Fuji Transonic SL climbs like a rocket but others on here said otherwise about aero bikes in general and specifically the Tarmac vs Venge. The Fuji also feels like the laterally stiffest frame I've ever owned but I haven't ridden other high end modern bikes.

parajba
Posts: 613
Joined: Tue Oct 28, 2008 9:00 pm
Location: London, United Kingdom

by parajba

robeambro wrote:
Fri Dec 07, 2018 3:32 pm
taodemon wrote:
Fri Dec 07, 2018 3:21 pm
robeambro wrote:
Thu Dec 06, 2018 5:21 pm
Same! Science (and even geometry for me) says SL6 .. But that Venge, man ...
(and also partly, I think the SL6 doesn't look good in black, and I can't bring myself to like any of the other paintjobs)
Have you seen the new paint jobs for 2019? Pretty much everything that was available as disc only before is now also available in rim if that was a consideration(it was for me). That means if I had been a bit more patient I would have finally gotten the chameleon frame I've been dreaming of for years. Ended up going with the black womens frame.
I have, and the chameleon seems nice, I'm only afraid that it would look too "purple" in real life. I would like to see it.. But we're OT :mrgreen:

Now, to go back in topic, I think that for example the new Izalco Max is how aero bikes for the pro peloton should be. It may make a great GC contender bike.
It has most of the desirable aero features, including dropped seatstays, fully internal cabling and aero cockpit. It's not a feather but I reckon with tubulars may be very close to the UCI limit.

The only problem is that the white colourway is a bit out of my price range :mrgreen:
Totally agree re the new Izalco Max. The dropped seat stays and the handlebar / stem / top of the fork are so sexy. All bikes are becoming quite similar but hey, the ones with traditional seat stays look so old now (e.g. Cervelo R5). I wish Cervelo made an R5 with some aero features like dropped seat stays and better handlebar / cable management!

packetloss
Posts: 31
Joined: Fri Dec 11, 2015 2:29 pm

by packetloss

Lelandjt wrote:
Fri Dec 07, 2018 9:24 pm
Lelandjt wrote:
Thu Dec 06, 2018 8:58 am
Isn't the Tarmac laterally and torsionally stiffer than the Venge?
No one answered before so I'm asking again and we can broaden this to include everyone's climbing bike vs aero bike. Since almost everything can be built to 6.8kg is the difference in climbing feel* that aero bikes are flexier when you're climbing out of the saddle?

*I'm not saying there's a difference. I think my 6.6kg Fuji Transonic SL climbs like a rocket but others on here said otherwise about aero bikes in general and specifically the Tarmac vs Venge. The Fuji also feels like the laterally stiffest frame I've ever owned but I haven't ridden other high end modern bikes.
To me the Venge Vias feels a lot stiffer than the Tarmac (SL5 or SL6) seated or out of the saddle. It certainly didn't help in any way for climbing. Quite the contrary, out of the saddle efforts while climbing felt more strained than on the Tarmac. Best way I can describe it is climbing efforts felt effortless on the Tarmac compared to the Venge.

packetloss
Posts: 31
Joined: Fri Dec 11, 2015 2:29 pm

by packetloss

parajba wrote:
Thu Dec 06, 2018 3:04 pm
robeambro wrote:
Thu Dec 06, 2018 2:41 pm
parajba wrote:
Thu Dec 06, 2018 2:02 pm
Lots of interesting points here.

Does anyone know how little or big is the drag of the frame/wheels compared to the rider?
Frame is very little, less than wheels, and if I recall correctly, even handlebars (shape of the bar + internal cable routing).

Of course, this is not to say that an aero frame is useless, but if one were to dial in an aggressive position (as much as biomechanics would allow), fit deep wheels and have narrow aero handlebars with no cables in sight, adding an aero frame to the equation would definitely not bring huge changes. And probably any aero improvement would be offset by a loss of comfort.

But this is a lot of science, the problem is that some aero bikes are darn sexy. :mrgreen:
100% Spot on. Trying to decide myself between Venge / SL6. The rational me says SL6, but the new Venge is so so so sexy.
Haven't tried the 2019 Venge, but based on having a Vias, SL5 and an SL6 I would caution you against buying the Venge unless you can take one out for a decent test ride with some climbs first. An SL5 or 6 i can guarantee you won't be dissapointed with.

nulldreiundreissig
Posts: 36
Joined: Tue Oct 02, 2018 11:13 am

by nulldreiundreissig

I had the opportunity to test ride a brand new cannonball systemsix and SS EVO almost back to back. It wasn’t a fair comparison spec-wise, but I think I got the same sensation as you guys.
Although it felt great in (uphill) sprints (up to a minute), I didn't get the sensation I was expecting on longer climbs. Its handling felt slow in a way I wasn’t expecting, although it was objectively fast. The SS Evo felt more lively and agile on climbs, not only weight wise, but also in the way it behaved.

ichobi
Posts: 979
Joined: Thu Jan 19, 2012 11:30 pm

by ichobi

Your questions about cockpit / frame aero differences have actually been answered, by Specialized themeslves.

This is in the Venge whitepaper which as far as I know is hard to find in public.
Screen Shot 2018-12-08 at 14.33.34.jpg
They compare Tarmac SL6 with the new Venge.

Tarmac in this plot comes in 3 specs.

1. CLX50 wheels + Round bar
2. CLX 50 + Aerofly 2 Bar
3. CLX 64 + Aerofly 2 Bar

Venge in one spec

1. CLX 64 + Aerofly 2 Bar

So you can see there's still some gap between the Tarmac SL6 and the Venge in the same configuration. As someone said above, the aero frame will have other elemments like the seatpost more aero than the all round bike too. So even if frame is just 16% of the equation, it's still tangible.

I myself rides a Tarmac SL6 with full integrated Black Inc Cockpit. I also ride latex tube with spe turbo cotton. All bearings are lubed with light oil with grease cleared out. I can really notice the speediness of the bike, quite similar to my previous Canyon Aeroad CF SLX. It's still a tad slower, but it rides much smoother, lighter (6.45kg), climbs heaps better.

I also tried the new Venge. Very good bike, but as I favour the all around aspect of riding, I choose the Tarmca with aero package. Do it all, and dont really miss out much really.

by Weenie


AJS914
Posts: 3585
Joined: Tue Jan 28, 2014 6:52 pm

by AJS914

I've seen that chart from Specialized in the past and my thought was that there is hardly any difference. If I'm reading the chart correctly I see that they are showing 6 bars for each .01 of cda. That comes out to a difference of:

.007 cda (fastest Tarmac compared to Venge)
.013 cda (slowest Tarmac compared to Venge)*

I think this tells us that handlebars and wheels make a decent difference.

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