Low hanging aero fruit - handlebars?

Discuss light weight issues concerning road bikes & parts.
spartacus
Posts: 45
Joined: Mon Apr 04, 2011 6:53 pm

by spartacus

I keep hearing some people claim the handlebars make more of a difference than the frame or possibly even the wheels. What do you think? Am I throwing away watts by not having aero-profile bars? People claim to notice a difference by using aero wheels, has anyone actually noticed a difference from the bars? What about my K-edge?

pdlpsher1
Posts: 1715
Joined: Thu Jul 19, 2012 6:09 pm
Location: CO

by pdlpsher1

I've heard the same claim on aero helmets. If you look at the helmet it has a huge front area, one that is much bigger than the horizontal part of the handlebar. Although an aero helmet doesn't reduce the frontal area from a non-aero helmet, the opportunity to reduce air drag is far greater than reducing drag on a handlebar IMHO. I went out and bought an aero helment, one that was tested to be the fastest in a wind tunnel (Bontrager Ballista). While I can't prove that I'm faster than before, the biggest difference it made is noise, or lack of it. It's so much more quieter than my non-aero helmet while riding. I attribute this to a significantly reduced air turbulence. So in summary I think the helmet is a lower hanging fruit than a handlebar. Also if you go with the handlebar route you must also hide all of the cables as all aero bikes do nowadays.

by Weenie


morganb
Posts: 601
Joined: Wed Mar 15, 2017 5:30 pm

by morganb

I think if you are going to go out and get aero bars and want a noticeable difference, I'd consider going narrower at the same time. Going from 42cm to 38cm is definitely worth some free watts.

spartacus
Posts: 45
Joined: Mon Apr 04, 2011 6:53 pm

by spartacus

FWIW I already have 40CM bars and an aero helmet, though I'm sure my helmet isn't the best one - and my frame isn't aero, etc... I know there are lots of other areas to look at and I'm not ignoring them or discounting them. I'm just specifically wondering whether or not the handlebar thing is really worth exploring. I think it's really interesting reading reviews about aero wheels where people rant and rave about how fast they feel and how they go out and beat their strava PRs on the first ride, but I've never heard someone say that about getting aero profile handlebars and an aero helmet for example - even though as far as I can tell the data suggests those two things or maybe even one of those things could theoretically make a similar difference in speed depending on many factors obviously.

rlpaul
Posts: 147
Joined: Thu Oct 30, 2008 9:25 pm

by rlpaul

It's leading edge in clean air, so it'll have more effect than, say, aero seatpost. The people claiming handlebars have bigger impact than wheels are trying to sell you something though. Frame only has one leading edge, the head tube, but there's a lot more frame than bars. Most of the aero bars I've seen claim ~8 watts savings, whereas every aero frame claims double digits.

I wouldn't be surprised as pdlpsher1 mentioned that helmet is a better area to save drag on. Only reason I haven't bought one is I already have three viable helmets, so until those are ready for replacement... Clothing with aero properties (such as the Castelli stuff Sky used, at least until yesterday's ban by the UCI), likewise, probably has more impact. But then, handlebars are always on the bike, and clothing gets dirty, needs replaced, doesn't matter cause it's too cold out and you need an outer shell anyways, etc.

I haven't noticed a difference with the aero bars, but I certainly notice a difference switching between wheels. But then my wheels are somewhat extreme - 20 deep, or 60 front, 70 rear. I'm sure the bars help, just not enough of a difference to feel it.

spartacus
Posts: 45
Joined: Mon Apr 04, 2011 6:53 pm

by spartacus

^ That's the interesting thing, if the bars save 8 watts or even 5 watts that's a huge amount for doing basically nothing - as far as I'm concerned. Not to mention all the other stuff like the helmet, wheels, skinsuit, shoe covers, etc... If you do the "aero math" it sounds like it's possible for one bike+outfit to be 30+ watts faster than another otherwise perfectly fine roadbike and kit, which sounds like an enormous difference as far as I'm concerned, and it really makes me wonder what I'm giving up compared to other guys with fancy setups considering my bike is basically traditional although my position is probably in the range of "good".

IchDien
Posts: 340
Joined: Mon Nov 05, 2012 12:23 am
Location: Veneto

by IchDien

rlpaul wrote:
Sat Oct 20, 2018 6:35 pm
at least until yesterday's ban by the UCI),
What's this?

rlpaul
Posts: 147
Joined: Thu Oct 30, 2008 9:25 pm

by rlpaul

Five watts is probably more accurate than the 8 that I keep hearing, as marketing tends to overstate, or only use ideal conditions. I agree that it's worth having, but I wouldn't put it top of my list. I have aero bars on my build, obviously, but that's because I already have wheels, not interested in an aero frame right now, and the bars help regardless of what phase of positioning I'm working on. And I'm always working on positioning, free speed is free speed when riding solo and have nobody to draft behind.

If I finally do the Assault on Mount Mitchell like I keep saying I want to, that may be the only 'local' ride I'd opt for complete weenie parts rather than aero. But then, that's over 10k feet of climbing...

rlpaul
Posts: 147
Joined: Thu Oct 30, 2008 9:25 pm

by rlpaul

IchDien wrote:
Sat Oct 20, 2018 6:50 pm
rlpaul wrote:
Sat Oct 20, 2018 6:35 pm
at least until yesterday's ban by the UCI),
What's this?
The Castelli clothing that Sky wears, as well as the similar clothing that Movistar wears (don't remember which brand they use), were banned yesterday. Unfair advantage, yadda yadda. Interstingly, Castelli claims they have new UCI legal clothing that's even faster, so... :noidea:

Stueys
Posts: 214
Joined: Sat Nov 22, 2014 1:12 pm

by Stueys

Ultimately there's no real downside to having aero bars over round bars other than the cost of buying them. So if you're fine with the cost then why not? Personally I swapped my enve round bar for a 3T aeronova and like it, (i) it's got flared bars so my 42 is 40 on the hoods and 42 on the drops, and (ii) round tubing tends to do very badly in aerodynamics so having a horizontal aerofoil as opposed to a round bar can only improve things. I doubt it gives you anything more than 4-5 watts but it all adds up

blaugrana
Posts: 28
Joined: Wed May 24, 2017 9:49 pm

by blaugrana

The main downside is the reduced variety in handlebar shapes to choose from, especially for integrated bars and stem. For example, I don't think there is anything with traditional round bends except for what Yates was riding in the Vuelta, which I'm assuming is custom made.

Also, round or slightly oval shapes with tape are generally more comfortable than very long aero shapes left untaped, but of course it comes down to personal preference (and how much time you spend on the tops).

bilwit
Posts: 961
Joined: Sun Apr 03, 2016 5:49 am
Location: Seattle, WA

by bilwit

5W measured with or without a rider? :wink:

BikeRadar did a wind tunnel test with wrapped aero bars that showed only a 1W difference between wrapped and no wrapped.. but the configuration they showed was without a rider altogether which makes me think that the actuals savings is magnitudes less than this number

hannawald
Posts: 316
Joined: Sat Dec 17, 2016 7:28 pm

by hannawald

Probably weight and stiffness?Aero bars tend to be noodly unless heavier. At least what i have read..

robertbb
Posts: 546
Joined: Thu Jul 23, 2009 3:35 am
Location: Melbourne, Australia

by robertbb

bilwit wrote:
Sat Oct 20, 2018 9:04 pm
5W measured with or without a rider? :wink:

BikeRadar did a wind tunnel test with wrapped aero bars that showed only a 1W difference between wrapped and no wrapped.. but the configuration they showed was without a rider altogether which makes me think that the actuals savings is magnitudes less than this number
^^^ Truth.
It's ALL about the bike.

RobertBB's CyclePlanner Spreadsheet:
https://weightweenies.starbike.com/foru ... 8&t=152263

by Weenie


RocketRacing
Posts: 66
Joined: Thu May 10, 2018 2:43 am

by RocketRacing

Lets do some very rough armchair math:

It all comes down to the rider being about 70% of the drag of the bike. I recall one source saying something to the effect of the front wheel, fork, and bars making up the lions share of bike only drag... at maybe 20% each. So bars would be 20%x30% or 6% overally bike and rider drag.

Now... another diagram by zipp showed the drag of rider and bike at various widths of bars, and finally the narrowist with aero shape. If memory serves, the switch from non aero to aero bars was the equivalent in aero gains to going one width narrower (say 42 to 40cm). Their numbers looks super impressive as far as free watrs, but that was because the rider position was changing... and that is where the big gains are.

I say if you want truly “free” watts, keep the old bars and drop a spacer or two. I also unwrap my bar tops.

Go with aero bars if you wish... it will be free gains, but i think any feel of speed gains will be in the head, as such a small change is really in the margin of error in shorter rides/human speeds.

My approach has been to adress the aero low hanging fruit with an aero helmet (also go the smallest size that will fit), aero clothes. I opted to do a lightweight/comfortable climbing build with my bike, and ignore bike aero outside rider and position. It was a consious choice that i know is probably slower... but i am a weight weenie at heart.

My next build will be all out aero, with no consideration of weight (thus why my climbing build has no consideration of aero outside the rider). I like bikes with themes.

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