Compared to having the same computer on the stem?

I'm curious, and pretty sure somebody somewhere took the time to quantify it. But apparently my google-fu is weak.

Apparently not enough to discourage those in the pro peloton from using one.

I would imagine it would vary greatly, for example, between mounts. I'm definitely slower now that I have one of the chamfered K-Edge mounts instead of the rounded aero one. It's like riding through mud, and not squishy mud, thick, gooey mud.

I can't feel a difference, and my power numbers vs speed vs grade don't look any different. But that doesn't say much about the aerodynamics except that if there's a penalty, it's small enough not to matter for me.

But if everybody in the peloton is using one then it wouldn't matter because they'd all have the same advantage or handicap.

Polly less than unzipping your jacket a couple of inches to cool off does, is my guess. Though, I too would like to see the math.

You're just not fine tuned enough. You need to train for this. Start with a full sized sheet of plywood and work your way down in size.

you'll pay a bigger aero penalty for waving

Ok.

There's no real reason here, except that it's a very slow day at work and I've got to pass the time somehow.

But as a general rule, we roadies don't like to have things on our bikes. Adding weight is usually only ok if it makes you faster. Somebody at work asked me once why I don't have a kickstand, I tried to explain to them how that would be like eating your children or painting your house with polka dots, just completely unacceptable. But everybody loves mounts. And putting the computer in a better spot to glance down at, it doesn't seem like enough justification for a road nazi. So I got to wondering. Maybe these improve aerodynamics. Maybe they don't, but people think they do. Who knows? Not me, that's why I'm asking.

I think that's basically it. Well, that and it also looks better. Looks > anything else.

Cervelo claims that Garmin on stem is faster than out-front with their S5 aero bars. /shrug

Out-front is easier to see my massive incredible watts and average speed, tho.

Exactly.

BTW, what color is the computer..?

I believe there is more drag going on around the handlebars than we usually credit it, and I suspect that the stem mount, in spite of the optics adds little if any additional drag due to the turbulence. With a particularly aero handlebar and flipped stem it may be a different story.

I've actually been mulling over a side-mount on the stem, to get it behind the bars, but haven't yet because of this uncertainty. This is a trivial enough concern to warrant some testing IMO.

I hadn't considered that math. But that's probably it.

Red, of course. Red is 13 % faster than black and saves 29 seconds on a TT.

Having the mount up front would obviously serve to break the wind before the rest of the bike gets there - you are essentially drafting off the computer. Out-front mounts will probably be banned by the UCI for next season as soon as the wind tunnel data is reported, or after a Spanish rider reports an unexplained boo-boo or ouchie.

I have a motor hidden in my computer that makes it run faster. Does that make me a cheetah?

DC Rainmaker tested some mounts and a few other gadgets in a wind tunnel back in March.Bottom line: Keep mounts and computers flat, parallel to the ground.

The article is well worth reading entirely apart from testing aerodynamics.


-Tim-

I think the dc rainmaker article may be related to this video from the specialised win tunnel (yes, they call it a wn tunnel).

Following on the rear wheel of the guy in front of you definitely improves aerodynamics.

One reason I opted for fizik stem was for compatiblity with the direct connect Barfly option; I'm trying to convince myself this actually subtracts about 10 watts versus no mount/computer at all.

They called that a "parachute" when angled up like that.

Oh man, tell me about it! Like dragging a freakin parachute or not shaving your legs for 3 days in a row!

nah.. it's perfectly angled to send air right over the top of the stem bolts and straight down the top of the stem, while underneath the angle of the garmin is slicing thru the the air and sending the jetstream below the stem.

Maybe it's the excitement of it all. Will you screw the angle up and turn your Garmin into a parachute, or will you get it right? A game of skill and chance.