Peter Cole said:"gds" <[email hidden]> wrote
Quoted message said:If there wasn't you wouldn't see them in TT or Tri events.
The reason I've heard they're used in triathelon events is to "save the
hamstrings" for the running part. I don't know about this personally as
I've never done a triathelon.
Quoted message said:The reason
you don't see them more is that they are not allowed in most mass
start races. If they were allowed almost all racers would use them.
And conversely why do you think that (almost) all racers use aero bars
when allowed. (TT's)
Good question. I think it may have more to do with biomechanics than
aerodynamics. TT bikes are set up quite differently than normal racing
bikes, the rider is in a different position, being much more forward on the
bike. I think the question is whether "clip-on" aerobars on an otherwise
normally set up bike offer an (aerodynamic) advantage over riding in the
drops.
Quoted message said:I 'm not a physicist so won't argue the science. But I am an
empiricist and there is no question you go faster at = effort. I think
the idea of terminal velocity is flawed for this argument as the
question is what is the improvement in speed over a range of
conditions and speeds.
How is the argument flawed? I think that wind tunnel tests would be the
ultimate objective test. The article at analyticcycling.com published this
data, for a variety of headwinds/yaw angles and aerobar orientations. Did
you read it?
First, it's probably correct to say "wind tunnel tests would be the
ultimate objective test." But it's a mistake to conclude that the data
on analyticccycling.com is therefore better than the testimony you read
here. As I've said, and as it says on that site, aero effects are
sensitive to individual differences. To quote from that site: "These
results are highly dependent on the rider and bike. One should not draw
any general conclusions unless one is looking at one's own wind tunnel
data."
Second, I think it's a mistake to attribute aero bar performance gains
to just biomechanics, say from a more forward rider position (or
whatever). It's always been possible to set up a standard bike with a
more forward position. If that were the source of the benefit, it would
have been discovered long before aero bars, by racers tweaking their
riding position looking for advantages. Similarly, aero bars are used
to great success by roadie time trialers, who have no need to "save
their hamstrings for the running part" of a TT. Unless you're doing a
bi- or triathlon, there _is_ no running part (and a time trialist who's
done it right can't even stand at the end, let alone run!).
Aero bars, as they're usually set up, get the rider lower than the
drops. (My friends have commented on this when they've seen me move to
the aero bar.) They also make the rider narrower, by pulling the elbows
and arms toward the center of the bike. Both those effects reduce the
frontal area, which should result in more speed.
I also think the bars reduce the rider's form drag coefficient. While
these sorts of judgements are speculative (without, say, smoke trail
studies in a wind tunnel) it seems to me that the aero bar arm position
may part the wind more gradually than the chest does, allowing a little
less turbulence by the air flowing around the torso.
Nonetheless, I've ridden with aero bars on my touring bike for about ten
years now. In my view, for my particular body geometry and bike setup,
they add at least a mile per hour over 20 mph air speed - and I've
demonstrated this to _my_ satisfaction at least a few thousand times.
They also give me extra positions I find useful.
It may be that they won't do that for everyone. But they're one of the
most successful innovations of the last 20 years. I see no reason to
doubt their efficacy.
--
Frank Krygowski [To reply, remove rodent and vegetable dot com.
Substitute cc dot ysu dot
edu]
