Aerodynamics and water bottles

If you are doing at time trial, have optimized your position and speed and need to set a record, or
trying to defeat a competitor by a few seconds, then H2O bottle placing may make a difference, as
John Cobb suggests. Otherwise it makes absolutely no difference.

Andres

I always put the water bottle in the milk crate on the rear carrier, to keep it out of the wind.
Those seconds add up.
--
Ron Hardin [email hidden]

On the internet, nobody knows you're a jerk.

The largest aerodynamic drag on a bicycle is the rider (he/she IS thte biggest thing!).

The difference in aerodynamics caused by a waterbottle may make a difference in a long time
trial, but unless you're thinking about competing against Armstrong or Hincapie, I wouldn't worry
about it much!

May you have the wind at your back. And a really low gear for the hills! Chris

Chris'Z Corner "The Website for the Common Bicyclist": geocities.comczcornerOpen ↗

Check out this website for more than you ever wanted to know about aerodynamics & bicycles.
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Quoted message said:

"Going Postal" has an all new meaning > Thanks Guys, For a first ever

for US.

"Chris Zacho "The Wheelman"" <[email hidden]> wrote in message
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Quoted message said:

The largest aerodynamic drag on a bicycle is the rider (he/she IS thte biggest thing!).

The difference in aerodynamics caused by a waterbottle may make a difference in a long time trial,
but unless you're thinking about competing against Armstrong or Hincapie, I wouldn't worry about
it much!

May you have the wind at your back. And a really low gear for the hills! Chris

Chris'Z Corner "The Website for the Common Bicyclist": geocities.comczcornerOpen ↗

I have to differ. If you're competing against somebody that's equal or very slightly better, all
else considered, then aerodynamics will make a huge difference. There's always going to be somebody
out there who's in that range (ok, maybe not if you're at the very top), and if you've got a 1% time
advantage because of aerodynamics, you've just beat him by about one minute in an hour long time
trial. Granted, water bottles are really cutting the hair fine, but if you've got an aero bike, aero
helmet/fairing, wear a skinsuit, wear shoe covers, have at least a rear disc wheel.... well, then
it'll make a difference. I've personally noticed that a guy I ride with that has ZIPP 404 wheels and
an aero Aegis frame (beautiful bike, btw), while being much fitter than I, will roll noticeably
faster down a hill with very similar tires. Side by side, if we start at the same speed, both in an
aero tuck position (also, I'm a beanpole, he's fit but not skinny), he will end up at the bottom of
the hill first going noticeably faster. Its kind of impressive.

Jon Bond

Jon Bond said:

I've personally noticed that a guy I ride with that has ZIPP 404 wheels and an aero Aegis frame
(beautiful bike, btw), while being much fitter than I, will roll noticeably faster down a hill
with very similar tires. Side by side, if we start at the same speed, both in an aero tuck
position (also, I'm a beanpole, he's fit but not skinny), he will end up at the bottom of the
hill first going noticeably faster. Its kind of impressive.

All other things being equal, small differences in aerodynamics are important. But in this case, I
think it's the weight much more so than the Zipp wheels. Do a little experiment, try switching bikes
for a coast down (repeat several times).

"Chris Zacho "The Wheelman"" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

The largest aerodynamic drag on a bicycle is the rider (he/she IS thte biggest thing!).

The difference in aerodynamics caused by a waterbottle may make a difference in a long time trial,
but unless you're thinking about competing against Armstrong or Hincapie, I wouldn't worry about
it much!

May you have the wind at your back. And a really low gear for the hills! Chris

Chris'Z Corner "The Website for the Common Bicyclist": geocities.comczcornerOpen ↗

Yeah, but if it means beating your buddies by x seconds for bragging rights, it is indeed important!

Mike

"Chris Zacho "The Wheelman"" <[email hidden]> wrote in message
"]news:[email hidden]... [email hidden] (Jon

Bond) said:

Granted. But I was implying that, by competing against Lance thast you were competing
professionally. THEN, yes. it would matter! ;-3)

You are right, though, all else being equal...

I don't understand the contempt for useful information I've seen in this thread. The OP told us
something that was not about spending a vast amount of money to get some tiny advantage, it was
about doing something that costs almost nothing to get a small advantage. Indeed, the results were
counterintuitive and could lead people to not waste money on questionable do-dads (like behind the
seat bottle cages). That's beautiful -- confirming that what most people already have is the best
set-up and pointing to other easily implemented actions. Why does that deserve a "doesn't matter" or
"useless for most people reaction"? I see it as contempt for trying to go a little faster. That's
unfortunate.

And moreover, the difference were not insignificant. Did you actually read the article? They varied
over several tens of seconds over the course of an hour at high speed. While that might not matter
for commuting or just fooling around on the bike, even for a low-level bike racer in time trial that
is a real difference that could affect placing.

JT

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(John Forrest Tomlinson) said:

I don't understand the contempt for useful information I've seen in this thread. The OP told us
something that was not about spending a vast amount of money to get some tiny advantage, it was
about doing something that costs almost nothing to get a small advantage. Indeed, the results were
counterintuitive and could lead people to not waste money on questionable do-dads (like behind the
seat bottle cages). That's beautiful -- confirming that what most people already have is the best
set-up and pointing to other easily implemented actions. Why does that deserve a "doesn't matter"
or "useless for most people reaction"? I see it as contempt for trying to go a little faster.
That's unfortunate.

I agree with you. Moreover, we frequently read comments to the effect that, unless you a world-class
athlete, small improvements in aerodynamics are meaningless. That is nonsensical, unless the world
record is the only standard. In fact, it is easy to argue the converse [and be equally wrong]. A
fractional reduction in the air drag coefficient will, approximately, reduce ones time by the same
fraction. Consequently, the slower rider will save more time. Of course, dumping lots of cash merely
to set a personal record seems kind of silly. But that isn't what was being proposed.

Joe Riel

Joe Riel said:

A fractional reduction in the air drag coefficient will, approximately, reduce ones time by the
same fraction.

Actually, the fractional reduction in time is one third that of the reduction in the drag
coefficient. That, however, doesn't change the argument. To first order

dT/T = 1/3(dk/k - dP/P)

where T is the time it takes to complete a fixed length TT k is the aerodynamic drag coefficient P
is the riders power.

So a 3% decrease in the drag coefficient is equivalent to a 3% increase in the rider's power output.
Each will reduce the time by 1%.

Joe Riel