Aero bikes and the Pro peloton...

Discuss light weight issues concerning road bikes & parts.
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robeambro
Posts: 602
Joined: Sat Jul 07, 2018 6:21 pm

by robeambro

AJS914 wrote: ↑
Sat Dec 08, 2018 4:18 pm
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.
If you plug the numbers here you can get an idea of the watts saved.
www.aeroweenie.com/calc.html

For example, at 30kmh (not the usual 45kmh bs), having a CdA of .30 vs .313 (Venge vs slowest Tarmac) seems to yield a saving of around 5 watts.

Doesn’t seem much, but then again, even the “slowest Tarmac” is quite aero optimised and doesn’t have basic wheels either.

Again, science says Tarmac is just fine.. But one can’t just avoid falling in love for the Venge.
But let’s just say that if people buy it to be considerably faster (or if they claim it after they ride it), I call bs.

by Weenie


AJS914
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by AJS914

So, plugging some stuff into that calculator I get that at .007 improvement in CDA is worth about 30 seconds over 40km @ 250 watts. That equals a 5 watt improvement. The .013 improvement in cda is worth 1 minute and 10 watts. I chose 250 watts because maybe that is what a mere mortal could ride a time trial at. If you are a pro with a 400 watt FTP then the savings are much greater.

For me the take-a-ways are:

Put aero road bars and deep wheels on your current bike.

A Tarmac (aero-ish road bike) with an aero bar and wheels is a close alternative to a full aero road bike

An aero road helmet like the Evade is worth 10 watts - that's even cheaper than handlebars or wheels.

A skinsuit is worth 20 watts. Consider that for group ride or next race.

robeambro
Posts: 602
Joined: Sat Jul 07, 2018 6:21 pm

by robeambro

AJS914 wrote: ↑
Sat Dec 08, 2018 7:56 pm
So, plugging some stuff into that calculator I get that at .007 improvement in CDA is worth about 30 seconds over 40km @ 250 watts. That equals a 5 watt improvement. The .013 improvement in cda is worth 1 minute and 10 watts. I chose 250 watts because maybe that is what a mere mortal could ride a time trial at. If you are a pro with a 400 watt FTP then the savings are much greater.

For me the take-a-ways are:

Put aero road bars and deep wheels on your current bike.

A Tarmac (aero-ish road bike) with an aero bar and wheels is a close alternative to a full aero road bike

An aero road helmet like the Evade is worth 10 watts - that's even cheaper than handlebars or wheels.

A skinsuit is worth 20 watts. Consider that for group ride or next race.
Yep - however, if you consider a surge/sprint, all those wattages increase (try and plug in 60kmh) and even a frame only could be worth some 40-50 watts which is not to be sniffed at.

On the other hand, if you’re drafting it matters all very little.

So, in the end, it’s really difficult to say which bike would be best in practice. But yes, for us mere mortals, a Tarmac with deep wheels and aero bars will do the job.
(I’ll still get the Venge cause it’s hot)

hogehoge
Posts: 49
Joined: Mon Feb 25, 2013 11:59 pm

by hogehoge

AJS914 wrote: ↑
Sat Dec 08, 2018 7:56 pm
So, plugging some stuff into that calculator I get that at .007 improvement in CDA is worth about 30 seconds over 40km @ 250 watts. That equals a 5 watt improvement. The .013 improvement in cda is worth 1 minute and 10 watts. I chose 250 watts because maybe that is what a mere mortal could ride a time trial at. If you are a pro with a 400 watt FTP then the savings are much greater.

For me the take-a-ways are:

Put aero road bars and deep wheels on your current bike.

A Tarmac (aero-ish road bike) with an aero bar and wheels is a close alternative to a full aero road bike

An aero road helmet like the Evade is worth 10 watts - that's even cheaper than handlebars or wheels.

A skinsuit is worth 20 watts. Consider that for group ride or next race.
Do you have figures of the CDA improvment by going to aerobars and aerowheels over standard bars and say 30mm wheels?

Also shoe covers can help and are problably the cheapest equipment upgrade, and of course improving position has a huge saving.

diegogarcia
Posts: 551
Joined: Sat Apr 24, 2010 7:31 pm

by diegogarcia

So, calling all serious weight weenies. Given the ethos and early strategy of this site ( personally been a member here since early 2010) was to help people get sub 6.8kg or less weighing bikes, which many have strived for and others get lambasted for not attaining, how come many many dyed in the wool weight weenies now find that + 7 / + 8 kg aero bikes are acceptable, faster, better than sub 6.8kg bikes which people spent years striving for ? Is it that WW folk are sheep, impressionable, easily persuaded, marketing mans dream, gullible, niave, blind to what others see ? Interested to hear other peoples thoughts on this. Of course we all love cycling and the bikes, but it occured to me the other day that these heavy propitiary bikes are far removed from a weight weenies wet spaff of a bike.

AJS914
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by AJS914

The forum is more main stream and, I think, science has entered into sport. Stock groupsets have gotten a lot lighter. People used to make the logical conclusion that lighter was faster and now we see that things like aerodynamics and rolling resistance having a larger impact on overal speeds.

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kgt
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Location: Athens, Greece

by kgt

@diegogarcia
Nice post. I agree.
@AJS914
Scientism has entered into sport. Science was always there.

BTW whatever the new trends in our forum are I still believe that a hi-end road racing bike weighting 8-8,5kg is just ridiculous. And I believed the same in 2006 when I became a member of the forum.

robeambro
Posts: 602
Joined: Sat Jul 07, 2018 6:21 pm

by robeambro

diegogarcia wrote: ↑
Sun Dec 09, 2018 6:48 pm
So, calling all serious weight weenies. Given the ethos and early strategy of this site ( personally been a member here since early 2010) was to help people get sub 6.8kg or less weighing bikes, which many have strived for and others get lambasted for not attaining, how come many many dyed in the wool weight weenies now find that + 7 / + 8 kg aero bikes are acceptable, faster, better than sub 6.8kg bikes which people spent years striving for ? Is it that WW folk are sheep, impressionable, easily persuaded, marketing mans dream, gullible, niave, blind to what others see ? Interested to hear other peoples thoughts on this. Of course we all love cycling and the bikes, but it occured to me the other day that these heavy propitiary bikes are far removed from a weight weenies wet spaff of a bike.
To be honest, there’s no way to get it right. If you follow trends you’re gullible and naive, if you don’t follow them you’re old-fashioned/ignorant, either way you’re not doing it right.

For sure there is plenty more information nowadays than there was in the past - Weight was always there and easy to measure, while aerodynamics much less so.
Now all of us can access online calculators, videos, papers, and study how changes in weight/aero are affecting their performance.

Finally, to be honest I really don’t understand why people are so bothered by what others do. If others fall victim of marketing and buy a 8.5kg bike, so what? You still have plenty of choice of lightweight frames and components, and you can do whatever you like..

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kgt
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Location: Athens, Greece

by kgt

The irony is that never in this forum did members admire 8,5kg bikes. In fact most members would just ignore a >7,5kg bike. So the title 'weightweenies' is not relevant anymore. That's what diegogarcia said.

aeroisnteverything
Posts: 178
Joined: Fri Aug 24, 2018 4:43 pm

by aeroisnteverything

robeambro wrote: ↑
Sat Dec 08, 2018 5:44 pm
If you plug the numbers here you can get an idea of the watts saved.
www.aeroweenie.com/calc.html

For example, at 30kmh (not the usual 45kmh bs), having a CdA of .30 vs .313 (Venge vs slowest Tarmac) seems to yield a saving of around 5 watts.

Doesn’t seem much, but then again, even the “slowest Tarmac” is quite aero optimised and doesn’t have basic wheels either.

Again, science says Tarmac is just fine.. But one can’t just avoid falling in love for the Venge.
But let’s just say that if people buy it to be considerably faster (or if they claim it after they ride it), I call bs.
This. Plus IIRC tarmac is tested with CLX50 and Venge with 60s. Makes the frame comparison even closer.

And then we all have our reasons. As I mentioned in another thread, I just cannot get over those exposed cables and otherwise there’d be very little reason not to get a tarmac with an aeofly bar.

RyanH
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by RyanH

kgt wrote: ↑
Sun Dec 09, 2018 8:50 pm
The irony is that never in this forum did members admire 8,5kg bikes. In fact most members would just ignore a >7,5kg bike. So the title 'weightweenies' is not relevant anymore. That's what diegogarcia said.
Weightweenies still exists but it's lost some of its meaning since many stock bikes now come under 6.8kg. It's pretty hard to not build a sub 6.8kg bike, but that isn't being a WW. A WW will take a given frame/fork module and make it respectably light. In my opinion, a carbon rim brake bike isn't worthy of WW consideration unless it's under 6kg, maybe 6.3kg for a Ti bike and 6.8kg for a modern steel bike.

With the above idea that one can still be a WW but have different weight criteria due to frame material, then I don't think having a disc bike precludes one from being a WW, but maybe the bar should be set at 7kg or so. I mean, you can be a WW and MTB, but your idea of light is 8 or 9kg. However, people rolling around on 8kg road disc bikes aren't even trying and thus, are not weightweenies. You can hear it and see it when they won't swap a multitude of parts because they feel that Enve this or Zipp that is the best compromise of weight and performance.

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themidge
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by themidge

I haven't been on here all that long, but I think (going off myself and what I've read on this forum) that WW is about taking a frame or concept that you really love and trying to make it as light and high performance as possible. Maybe I'm just saying that because both my favourite frames are easily >1000g :D but if you take a look around the forum at builds like @Bmanx's (aero + light), @RyanH's (Ti frame), @ubergoober's English (steel, shame he had to put it up for sale I think) you see the same kind of thing. All those builds could be a few grams lighter if the frame was swapped out for a C'dale ss evo*, but it's the variance that makes WWs more exciting.

*no shade! They're just quite common and lightweight :D

burnthesheep
Posts: 4
Joined: Mon Dec 10, 2018 12:42 am

by burnthesheep

When you’re doing work in a way that’s going to get you up (down?) the power duration curve, 5 to 10 watts could mean a duration of 20min or an hour. Or popping and fading.

Whether in a break or climbing, use and save what ya got.

Also, in TT downhill aero matters on those little -1.0% or minus 1/2% grades where you can hold 30+ mph for minutes. That’s real air speed too, not a wind assist.

Same in a breakaway I’d suppose. You’re going down at some point. So those watt savings will come into play.

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