Why so few aero road bikes?

Triathlon Forum
1

I was in a LBS not long ago and was looking at some expensive high end carbon road bikes. All of them had big round or ovalized tubing. What really struck was the unaerodynamic big down tubes that all these bikes had. It’s well proven that the only thing less aerodynamic than round/ovalized tubing is bigger round/ovalized tubing. These were not cheap bikes, they were all high end carbon road bikes that many ST’ers drool over. But these bikes should be less aero than any smaller tubed steel or titanium road bike.

Off hand, I can only think of about three road frames that have made any attempt at aerodynamics - Cervelo Soloist, Kestrel Talon and Guru Maestro. I have to wonder why there aren’t more.

Some may argue that aerodynamics are less important in road racing or group rides, which is probably true, but improved aerodynmics can’t hurt. Note the trend to more aero wheels in this years TDF.

It seems like an industry trend that the manufacturers have been slow to pick up on.

2

I have a KHS road bike that has a aero down-tube/stead tuby and shallow rear wheel cut out.

I think the main reason is weight. They like to keep the bikes lite and stiff.

3

Off hand, I can only think of about three road frames that have made any attempt at aerodynamics - Cervelo Soloist, Kestrel Talon and Guru Maestro. I have to wonder why there aren’t more.

I can think of some others:

Shimano AX-equipped Miyata in early/mid 1980’s

San Rensho frameset from that period using some of the same tubing (I owned one of these until it was stolen)

Hooker Elite Cat. 1 (I owned one of these as well)

Trek Y-Foil (yup, you guessed it: I used to ride one)

Of course, there are, or were, a large number of aluminum frames with aero profiled downtubes or tubesets (e.g., GT Vengeance), and also other beam-style bikes that could be used in mass start races (e.g., Zipp 2001, 3001, various Softride models).

4

It just doesn’t seem like an important consideration for a road bike. How much difference wil an aero down tube make in a road race? Almost none I would imagine. Also, it is about sales and roadies don’t seem to care about that. Aero tubes are probably heavier and maybe less stiff?? Weight and stiffness would be more important to roadies (not that either of those considerations will affect your race performance either). Just a thought.

Mike

5

I have a KHS road bike that has a aero down-tube/stead tuby and shallow rear wheel cut out.

Oh yeah: the ZH2B tubeset. Always thought those were cool-looking bikes.

6

A couple of theories:

Cost …I suspect it costs more to build a aero downtube than a round one.

Tradition …I think a lot of roadies are traditionalists and would not be as quick to buy a “road” bike with aero tubing. They leave the aero bikes to us tri geeks.

Weight …aero bikes are heavier than equal road bikes …although they are getting lighter.

I agree with you that you would think they would build more aero road bikes …you would think that performance and getting to the finish line the fastest would be above all else …regardless of what it looked like.

7

I think part of it is that frame drag is a much smaller percentage of a road position than a TT position. I think it was posted somewhere that Pantani’s Cd on his road bike was 0.31, and he was tiny. 0.31 for a TT rider is the kind of Cd for someone double Pantani’s size.

I also think it has to do with tactics. In general, you are in the peloton, except when climbing. And when climbing, aerodynamics becomes less important.

Beyond that, I think it is important to consider ride quality. An aero tube, in general, will have worse vertical compliance (too stiff) and lateral compliance (too soft) compared with a round or otherwise shaped tube. Carbon has changed all this to some extent, since you can modify ride quality with lay-up, but for a non-carbon bike, it is much harder.

Cost and manufacturing is another issue. Round tubes and round lugs are easy to make. Cutting and fitting round tubes to another round tube for welding is easy.

Aerowheels are becoming more present because they have a big effect on acceleration. Despite being, in some cases, marginally heavier, they accelerate through the air much faster. There are also lots of company already making aero wheels. I think you are seeing more riders on Mavic Cosmic Carbones vs. Mavic Kysiriums. But these are wheels that are already being made.

Making aeroframes, for some companies like Time that use a lugged construction method, could mean massive changes. Changes that might take a long time to pay off. And when you consider that many teams still consider a lot of this aero stuff to be bunk, it’s not really surprising. I don’t think the general road riding public wants it, team riders don’t really know enough, so there is not a real demand.

I think that is the great irony about SlowTwitch. You have, to some extent, people that justify equipment choices “because the pros do it,” yet many of those same people probably have read more on equipment selection that many of the pros. Look at Jan Ullrich riding the Xentis wheel backwards. On the one hand, people say that his mechanic should have been fired. On the other hand, you might think Jan should know which way his wheel ought to go.

8

I fully suspect that things will trend back to “aero” in road bikes, for a few reasons.

There was a big aero push in road bike, after the GT Vengeance/ Edge Aero came out, and all of the big players (Giant/Raleigh/Special Ed) all had aero (or aero “look” bikes).

The big problem was that in aluminum, at least, the bikes tended to be heavy and ride quite harshly.

Then the industry trend went from “aero” to “how much does it weigh??”. This was also the death of deep aluminum clinchers that used to be spec’d on bikes.

With the weight of bikes about as low as they can really go (there will be sub 2lb frames from almost all of the big guys in '07), it’s the next logical trend. Manufacturers need something to talk about, and the weight thing has played out.

As far as ‘does it matter’?? I think anything that saves you watts when you’re just sitting in the pack is worthwhile, and even sitting in a pack, more aero is more beneficial–this extends from position to equipment…so I expect you’ll see a lot more attention paid to road position Cda and equipment over the next few years.

But, please–I hope some governing organization bans aero helmets from mass start events–some things are just too stupid-looking, no matter how effective…

9

I hope some governing organization bans aero helmets from mass start events–some things are just too stupid-looking, no matter how effective…
It could be worse: we all could be required to wear fabric covered helmets with a number on them, ala keirin racing in Japan.

10

I can think of some others:

Shimano AX-equipped Miyata in early/mid 1980’s

San Rensho frameset from that period using some of the same tubing (I owned one of these until it was stolen)

Hooker Elite Cat. 1 (I owned one of these as well)

Trek Y-Foil (yup, you guessed it: I used to ride one)

Of course, there are, or were, a large number of aluminum frames with aero profiled downtubes or tubesets (e.g., GT Vengeance), and also other beam-style bikes that could be used in mass start races (e.g., Zipp 2001, 3001, various Softride models).

I thought of another example: the Look 286/386/486 series, all of which make/made greater or lesser “concesions” to aerodynamics (I believe that Mike Plumb used to ride a have a silver-colored 286).

11

My '99 Klein has a massive round downtube on it. I consistently posted top-5% bike splits during tri races while riding it. I don’t think that fat tube was slowing me down any…

The aerodynamic benefits of the frame are nearly negligible, as opposed to the rider position it allows, which is the main benefit of a tri-specific frame. The rest is mostly just marketing hype.

Also, you are forgetting the target audience for road bikes. Roadies.

Roadies ride in packs 98% of the time. So the bike aerodynamics are that much less important, since they are sucking wheel anyway.

Also, most roadies are weight weenies. Aero tubing weighs more. They want light weight (admittedly somewhat misguidedly, but that’s another thread…), so a “heavy” aero-framed bike won’t appeal to them when they try to pick it up in the LBS with their spindly pipe-cleaner arms :wink:

12

I was wondering this myself. My main conclusion as to why there aren’t more (after I bought a Soloist Carbon) is the same as everyone else. Mainly, high end road bikes need to be light, and aero frames are generally much heavier (SLC is an exception). The Kestrel Talon is a good example here (and a mighty fine bike I might add). Also, they tend to ride a little stiffer as Rappstar mentioned than their “tuned” or round tube counterparts. Yes, aero is “less” important in the peloton, but if all other things are equal (stiffness, weight, etc.), then it is a no brainer to me. I personally think this is the magic in the Soloist Carbon and I do think more bikes will be heading this way in the future as the Taiwan factories are getting pretty good at carbon - unfortunately, it is going to make frames prices pretty damn expensive (as if they aren’t already).

13

Yeah, I thought your mention of the Shimano AX group was interesting, in light of the “revolutionary Sram group” thread…

If a component manufacturer (like Sram) really wanted to do something ‘revolutionary’, they’d have done a fully integrated “aero” group, like AX, then do a big marketing campaign about how many watts it saves.

They missed a big opportunity, IMHO…

14

Mostly b/c no one buys them. I inquired to Litespeed to build one (think Ghisallo geo with TiPhoon tubing) but was talked out of it…

Surprised this doesn’t get any love around here?

http://www.sevencycles.com/lib/img/products/bikes/diamasL.jpg