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External cables and aero drag?

Posted: Mon Apr 12, 2021 4:08 pm
by jesper2913
I have a 2016 Canyon Aeroad. The front brake cables comes out from under the handlebars and goes down to the front brake caliper like below. If I want to make my Aeroad more aero, is there a solution for that cable? And if we are talking aero, will that cable be an issue at all?

I know that we probably are in the single digits of watts, but we are weenies after all.

Similar problem for the rear brake. Are we talking a lot of watts? Or should I just move on.

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External cables and aero drag?

Posted: Mon Apr 12, 2021 4:08 pm
by Weenie

Re: External cables and aero drag?

Posted: Mon Apr 12, 2021 4:10 pm
by jih
Really, you need a frame and fork designed to work that way, and preferably hydraulic for the right bends, which probably means disc brakes too.

I'd not worry about it and get a tighter fitting jersey or cover up helmet vents to be more aero.

Re: External cables and aero drag?

Posted: Mon Apr 12, 2021 4:26 pm
by jih
You could cut the cables to be as short as they can be while still giving a clean line. From the factory they tend to have a bit of slack to accomodate riders who want to raise the bars.

Re: External cables and aero drag?

Posted: Mon Apr 12, 2021 4:31 pm
by Roadrocket
Forget it.
External cables are not making you any slower. I just remember that old gen Cervelo S5 was in test 1W faster than new all-integrated version with hidden cables. You have good and fast bike, just ride the sh.t out of it.
I wouldn´t even call the brake cables a ´problem´ :)

Re: External cables and aero drag?

Posted: Mon Apr 12, 2021 4:33 pm
by Lina
Outside of TTs makes absolutely no difference.

Re: External cables and aero drag?

Posted: Mon Apr 12, 2021 4:36 pm
by Steve Curtis
Marketing busllshit is making people paranoid.
The cable-s will probably be a watt or 2 at most. You're probably loosing considerably more than that elsewhere.

Re: External cables and aero drag?

Posted: Mon Apr 12, 2021 4:59 pm
by Ypuh
Considering MvdP won last years RVV with intergrated cables from Wout van Aert who rides with external cabling. This year MvdP had to switch to external cables due to the Canyon debacle, and Asgreen won with the internal cabling.

Based on that I'd estimate it probably cost him 20+ watts and is the clear difference between winning and losing.

Re: External cables and aero drag?

Posted: Mon Apr 12, 2021 5:00 pm
by Hexsense
I'd not totally hide the cable on that bike.

The furthest I'd go is to use Tririg Omega One front brake, which has cable entrance in-line in front of the head tube rather than off the side,
https://www.tririg.com/store.php?c=omegaone

And possibly zip tie other cables around stem and spacers to get it tuck as close to the frame as possible.
Finally, I'd make sure to zip tie di2 rd cable around the hanger to, again, make sure it hug along other components rather than sit proud in the wind.

But all of these might not make any meaningful different. Just look a little nicer.

Re: External cables and aero drag?

Posted: Mon Apr 12, 2021 5:08 pm
by gurk700
Please stop buying into marketing crap.
Think about you, your bike, and the cables that stick out in the wind.

How much do you really think the cables can hurt your overall drag compared to you or your frame / wheels / rest of the bike?

Re: External cables and aero drag?

Posted: Mon Apr 12, 2021 5:44 pm
by Singular
I think the consensus is that 10cm of exposed cable housing in isolation is about one watt in drag at relevant speeds. With that said, it's really hard to do anything about it as there is no alternative routing of a cable rim brake that works (especially on a bike/fork/handlebar that is not constructed that way initially). The only viable option would be rim hydros (like what was offered from SRAM not very long ago), as these permit a routing that would never be possible with a cable.

...and for what it's worth, a "conventional" front rim brake is still more aero than a disc brake.

Re: External cables and aero drag?

Posted: Mon Apr 12, 2021 5:48 pm
by usr
jesper2913 wrote:
Mon Apr 12, 2021 4:08 pm
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If it looks like this (cable bulging outboard above the brake) you can easily remove a few centimeters and since the front brake cable ends there it's a simple job (no re-threading). Just make sure that there is still sufficient housing for a clean line when the brake is closed, on worn down pads, with the barrel adjuster on lowest setting. I did the same on my gen 2 Aeroad recently (initial housing setup was with a spacer stack and a competent different cockpit) and it looks much cleaner now.

For other cables that also appear too long
I'd wait for the next routine wear replacement, because with those there'd be too much re-threading work after cutting the front housings. And re-threading may or may not work with a cable that was already cut.

Re: External cables and aero drag?

Posted: Mon Apr 12, 2021 7:55 pm
by mike
Unless You are a professional forget about the cable and just ride

Re: External cables and aero drag?

Posted: Mon Apr 12, 2021 8:02 pm
by skymasternl
Internal cabling has a nice and clean look for sure but has minimal performance gain (perhaps less than 2W saved at 40 km/h? )

Full internal cabling can usually be achieved much more easily with electric shifting and hydraulic brakes because they can be bent around a much much tighter radius than mechanical cables.

So unless you are absolutely obsessed with the clean look, for me I wouldn't bother at all.

Re: External cables and aero drag?

Posted: Mon Apr 12, 2021 8:58 pm
by Miller
Be careful about cutting cables too short. It's annoying to find you can't remove the stem from the fork because the brake cable has maxed out of flex. Or so I've heard.

Re: External cables and aero drag?

Posted: Mon Apr 12, 2021 8:58 pm
by Weenie

Re: External cables and aero drag?

Posted: Mon Apr 12, 2021 9:24 pm
by rides4beer
Canyon said the difference on the new Aeroad was 3w for fully internal cables.