Guesstimating CdA

Dans le message de news:[email hidden],
[email hidden] <[email hidden]> a réfléchi, et
puis a déclaré :

Quoted message said:

Hi All,

In an effort to impress my riding buddies with my magical abillity to
accurately predict my TT results (Thanks to Ron Ruff's great
spreadsheet!), I have been playing with calculations for power, speed,
etc. I don't have a power meter and I'm not going to get one any time
soon, so all this is theoretical and just for fun anyway.

I have determined that my CdA while on my TT bike with normal wheels
(Deep V, 28, 32) and normal riding clothes and a normal helmet is .29.

Using published figures for wheel drag, how would I go about
estimating what my CdA would be using different wheels like deep-
section carbon front and back, tri-spoke front, disc back, etc?

And what would a TT suit and helmet do to my CdA?

Joseph

A1 - .29
A2 - make you look funny

Get a grip! Train. You going pro ??

Sandy said:

Dans le message denews:[email hidden],
[email hidden] <[email hidden]> a réfléchi, et
puis a déclaré :

Quoted message said:

Hi All,

Quoted message said:

In an effort to impress my riding buddies with my magical abillity to
accurately predict my TT results (Thanks to Ron Ruff's great
spreadsheet!), I have been playing with calculations for power, speed,
etc. I don't have a power meter and I'm not going to get one any time
soon, so all this is theoretical and just for fun anyway.

Quoted message said:

I have determined that my CdA while on my TT bike with normal wheels
(Deep V, 28, 32) and normal riding clothes and a normal helmet is .29.

Quoted message said:

Using published figures for wheel drag, how would I go about
estimating what my CdA would be using different wheels like deep-
section carbon front and back, tri-spoke front, disc back, etc?

Quoted message said:

And what would a TT suit and helmet do to my CdA?

Quoted message said:

Joseph

A1 - .29
A2 - make you look funny

Get a grip! Train. You going pro ??

Man, you crack me up. You think I would look funny in a borrowed TT
suit? You should see me in the XC skiing suit I've been contemplating
using! It was so pathetic my wife actually refrained from laughing
when she saw me try it on!

My problem is I'm almost 100kg and the road races around here have too
many hills. Even the one last Tuesday that was "flat" according to
everyone, had 390m of ascent over 57km. Not exactly an Alpine stage,
but more than enough for me to get dropped. And therein lies the
problem! I am WAY better than all the guys I usually get dropped with,
but to all the top guys, I'm just another guy who got dropped. But
were I to focus on some flat TT's I could make a mark of sorts on the
result list. I think with a little improvement I could break 14
minutes for 10km. No exactly pro, but fast enough to be a "somebody"
around here.

Joseph

Quoted message said:

But
were I to focus on some flat TT's I could make a mark of sorts on the
result list. I think with a little improvement I could break 14
minutes for 10km. No exactly pro, but fast enough to be a "somebody"
around here.

Dude, rather than waste time with a skin suit and aero wheels, why
don't you cut to the chase and dope? Plus, later on you can admit it
(suggestion: publicly and tearfully) and everyone will think you're a
real somebody.

Meanwhile, if you really want to know how much aero wheels will save,
use the power-speed-drag equation to convert to drag force, then
adjust for the new wheels, then convert back.

Quoted message said:

Quoted message said:

But
were I to focus on some flat TT's I could make a mark of sorts on the
result list. I think with a little improvement I could break 14
minutes for 10km. No exactly pro, but fast enough to be a "somebody"
around here.

Dude, rather than waste time with a skin suit and aero wheels, why
don't you cut to the chase and dope? Plus, later on you can admit it
(suggestion: publicly and tearfully) and everyone will think you're a
real somebody.

Who's to say I don't already? Send a SASE and I'll return a sample.

Quoted message said:

Meanwhile, if you really want to know how much aero wheels will save,
use the power-speed-drag equation to convert to drag force, then
adjust for the new wheels, then convert back.

Ok!

Joseph

Quoted message said:

On May 25, 6:38 pm, [email hidden] wrote:

Quoted message said:

Quoted message said:

Dude, rather than waste time with a skin suit and aero wheels, why
don't you cut to the chase and dope? Plus, later on you can admit it
(suggestion: publicly and tearfully) and everyone will think you're a
real somebody.

Who's to say I don't already?

You're already doping and you get dropped on a little hill? Ouch. I'm
thinking wheels and a skin suit ain't going to be enough.

Quoted message said:

Quoted message said:

Quoted message said:

Dude, rather than waste time with a skin suit and aero wheels, why
don't you cut to the chase and dope? Plus, later on you can admit it
(suggestion: publicly and tearfully) and everyone will think you're a
real somebody.

Quoted message said:

Who's to say I don't already?

You're already doping and you get dropped on a little hill? Ouch. I'm
thinking wheels and a skin suit ain't going to be enough.

Hey, rub it in why don't you? Maybe I should just call a press
conference now so I feel better.

Joseph

email hidden said:

Using published figures for wheel drag, how would I go about
estimating what my CdA would be using different wheels like deep-
section carbon front and back, tri-spoke front, disc back, etc?

And what would a TT suit and helmet do to my CdA?

Your rims are fairly good in the aero dept, but all those round spokes
are not helping. The best aero wheels (yes, use a disk in back... or
much cheaper a wheel cover) should be good for ~1-2% boost in your top
speed (more if there is a strong sidewind). I'll let you figure how
much CdA that is.

I don't know exactly what a skin suit and aero helmet will do, but if
you want to maximize your performance, I think you should spend the
money... it's enough to notice on the stopwatch at least.

Optimizing your position will have the biggest effect, though...

How much do you need to improve your W/CdA before you get on the
podium?

Ron Ruff said:

On May 25, 9:45 am, "[email hidden]"

Quoted message said:

Using published figures for wheel drag, how would I go about
estimating what my CdA would be using different wheels like deep-
section carbon front and back, tri-spoke front, disc back, etc?

Quoted message said:

And what would a TT suit and helmet do to my CdA?

Your rims are fairly good in the aero dept, but all those round spokes
are not helping. The best aero wheels (yes, use a disk in back... or
much cheaper a wheel cover) should be good for ~1-2% boost in your top
speed (more if there is a strong sidewind). I'll let you figure how
much CdA that is.

I don't know exactly what a skin suit and aero helmet will do, but if
you want to maximize your performance, I think you should spend the
money... it's enough to notice on the stopwatch at least.

A guy I know just said I could borrow his helmet indefinitely. Which
is more important for a suit, the smoothness of the fabric or the lack
of flapping? I have an XC suit (which doesn't look as foolish as I
joked about) that fits very snug and does not flap at all, but is a
coarse thick lycra. Buying more stuff isn't high on my list yet.

Quoted message said:

Optimizing your position will have the biggest effect, though...

My position is as low and flat as I can get it. I maybe could get my
elbows closer. I'll take some pics.

Quoted message said:

How much do you need to improve your W/CdA before you get on the
podium?

If I got a CdA down to .27 I'd be a contender. If it dropped to .26
I'd be dangerous. Wattage at functional threshold is I believe 390,
and I don't know how much more to gain there is in that department,
but that is a whole different subject.

Joseph

email hidden said:

A guy I know just said I could borrow his helmet indefinitely. Which
is more important for a suit, the smoothness of the fabric or the lack
of flapping? I have an XC suit (which doesn't look as foolish as I
joked about) that fits very snug and does not flap at all, but is a
coarse thick lycra. Buying more stuff isn't high on my list yet.

I'd give that XC suit a try if it isn't too hot.

Quoted message said:

If I got a CdA down to .27 I'd be a contender. If it dropped to .26
I'd be dangerous. Wattage at functional threshold is I believe 390,
and I don't know how much more to gain there is in that department,
but that is a whole different subject.

I bet you make it. As I recall, you are pretty new to this game. 390W
is a lot of power even for a big guy, but it will surely get better
with further training.

I think you should check out the forum at BikeTechReview... lots of TT
experts over there.

BTW, I put up a new version of the spreadsheet if anyone is
interested:
http://www.whitemountainwheels.com/SpeedPower.html

Quoted message said:

Using published figures for wheel drag, how would I go about
estimating what my CdA would be using different wheels like deep-
section carbon front and back, tri-spoke front, disc back, etc?

Have you considered smearing yourself all over with Vaseline?

--
Home page: http://members.westnet.com.au/mvw

Michael Warner said:

Quoted message said:

Using published figures for wheel drag, how would I go about
estimating what my CdA would be using different wheels like deep-
section carbon front and back, tri-spoke front, disc back, etc?

Have you considered smearing yourself all over with Vaseline?

--
Home page:http://members.westnet.com.au/mvw

It is dandelion season. I'd look like the Abominable Snowman before I
even got anywhere.

Joseph

email hidden said:

Quoted message said:

Quoted message said:

On May 25, 6:38 pm, [email hidden] wrote:
> Dude, rather than waste time with a skin suit and aero wheels, why
> don't you cut to the chase and dope? Plus, later on you can admit it
> (suggestion: publicly and tearfully) and everyone will think you're a
> real somebody.

Ignore the naysayers - I'm on your side. Ride smart!

Aero wheels will up your average at least 2 kph (based on my
experience with a 50mm Mavic Carbone.) A 10 minute gain per 40 kms is
the expected 'standard.' Put the best tyres on them that you can
afford (the new tubeless Hutchinson looks good) and fine tune the
pressure for the surface you're riding on. If it's a bit rough, a
slightly lower pressure will be faster.
If you can afford ceramic wheel bearings you'll gain a bit more. Ditto
with the BB and also get oversized and ceramic bearing jockey wheels.

Another big dragger is the helmet - a Chronos or similar time trial
helmet will make a noticeable difference.

Lightweight cranks and pedals will add a little and conserve your
energy. Carbon soled shoes are a must to maximise the power.

I have no idea what a skinsuit will do but I know that a half open
jacket gives noticeable drag - so I'd expect 1/2 to 1 kph minimum.

Tune your tuck position by finding a long hill and measuring your
maximum speed in various positions.

Do yourself a Conconi test to find your sustainable aerobic maximum.

Use a Powerbreathe or practice breathing with the bottom half of your
lungs - that's where the major oxygen absorption takes place.

Study the nutrition required. Also use a protien/mineral/vitamin drink
after training (within 20 minutes) to aid recovery and build muscle.

Training is good, but you can train until your eyeballs fall out and
be very slow unless you pay attention to details and ride smart. Age
and treachery etc...!!

lightninglad said:

On May 26, 4:35 am, "[email hidden]"

Quoted message said:

On May 25, 7:52 pm, [email hidden] wrote:

Quoted message said:

Quoted message said:

<[email hidden]> wrote:
> On May 25, 6:38 pm, [email hidden] wrote:
> > Dude, rather than waste time with a skin suit and aero wheels, why
> > don't you cut to the chase and dope? Plus, later on you can admit it
> > (suggestion: publicly and tearfully) and everyone will think you're a
> > real somebody.

Ignore the naysayers - I'm on your side. Ride smart!

Aero wheels will up your average at least 2 kph (based on my
experience with a 50mm Mavic Carbone.) A 10 minute gain per 40 kms is
the expected 'standard.' Put the best tyres on them that you can
afford (the new tubeless Hutchinson looks good) and fine tune the
pressure for the surface you're riding on. If it's a bit rough, a
slightly lower pressure will be faster.
If you can afford ceramic wheel bearings you'll gain a bit more. Ditto
with the BB and also get oversized and ceramic bearing jockey wheels.

The wheels will happen one day. The other stuff is pretty unlikely,
but happily has the least effect, so I won't miss much.

Quoted message said:

Another big dragger is the helmet - a Chronos or similar time trial
helmet will make a noticeable difference.

Check. I've got a helmet now.

Quoted message said:

Lightweight cranks and pedals will add a little and conserve your
energy. Carbon soled shoes are a must to maximise the power.

Does weight on the cranks and pedals actually make a difference? No
real acceleration involved, so while one is going up, the other is
coming down. As for shoes, I'd really like some super stiff shoes, but
I might have to go custom to get them for my large size. I'm
considering Rocket 7, but the cost is making me wait.

Quoted message said:

I have no idea what a skinsuit will do but I know that a half open
jacket gives noticeable drag - so I'd expect 1/2 to 1 kph minimum.

Check!

Quoted message said:

Tune your tuck position by finding a long hill and measuring your
maximum speed in various positions.

This is logistically the hardest thing to do. It's far to a suitable
hill, and the weather conditions vary so much.

Quoted message said:

Do yourself a Conconi test to find your sustainable aerobic maximum.

I'm pretty confident I know my limits. I can predict within about 5
seconds my times on my local 10km out-and-back based on what HR I
chose. I also know what HR is best for different crank lengths. (Long
cranks, lower HR = fastest) So I'm pretty sure this is optimized
already.

Quoted message said:

Use a Powerbreathe or practice breathing with the bottom half of your
lungs - that's where the major oxygen absorption takes place.

That's interesting. From what I've read aspiration is far from the
weakest link in the aerobic chain.

Quoted message said:

Study the nutrition required. Also use a protien/mineral/vitamin drink
after training (within 20 minutes) to aid recovery and build muscle.

I always do, and as a result I recover well (based on comments from
riding buddies after rides we've been on together), and building
muscle is the least of my worries!

Quoted message said:

Training is good, but you can train until your eyeballs fall out and
be very slow unless you pay attention to details and ride smart. Age
and treachery etc...!!

Sound words. Thanks for the positive angle.

Joseph

lightninglad said:

Aero wheels will up your average at least 2 kph
A 10 minute gain per 40 kms is the expected 'standard.'

Hmmm. Let's see: 2 kph faster ==> 10 minute gain per 40 km ...

You TT at 12mph?

Dans le message de
news:[email hidden],
[email hidden] <[email hidden]> a réfléchi, et
puis a déclaré :

Quoted message said:

lightninglad said:

Aero wheels will up your average at least 2 kph
A 10 minute gain per 40 kms is the expected 'standard.'

Hmmm. Let's see: 2 kph faster ==> 10 minute gain per 40 km ...

You TT at 12mph?

Gee, you're picky today. Get rained on last night ?

Sandy said:

Gee, you're picky today. Get rained on last night ?

Nope. Apres moi le deluge.

Quoted message said:

Quoted message said:

Quoted message said:

<[email hidden]> wrote:

-Time trial improvement?-

Quoted message said:

Quoted message said:

Quoted message said:

> [email hidden] wrote:
>> Dude, rather than waste time with a skin suit and aero wheels, why
>> don't you cut to the chase and dope? Plus, later on you can admit it
>> (suggestion: publicly and tearfully) and everyone will think you're a
>> real somebody.

lightninglad said:

Ignore the naysayers - I'm on your side. Ride smart!

Aero wheels will up your average at least 2 kph (based on my
experience with a 50mm Mavic Carbone.) A 10 minute gain per 40 kms is
the expected 'standard.' Put the best tyres on them that you can
afford (the new tubeless Hutchinson looks good) and fine tune the
pressure for the surface you're riding on. If it's a bit rough, a
slightly lower pressure will be faster.
If you can afford ceramic wheel bearings you'll gain a bit more. Ditto
with the BB and also get oversized and ceramic bearing jockey wheels.

Another big dragger is the helmet - a Chronos or similar time trial
helmet will make a noticeable difference.

Lightweight cranks and pedals will add a little and conserve your
energy. Carbon soled shoes are a must to maximise the power.

I have no idea what a skinsuit will do but I know that a half open
jacket gives noticeable drag - so I'd expect 1/2 to 1 kph minimum.

Tune your tuck position by finding a long hill and measuring your
maximum speed in various positions.

Do yourself a Conconi test to find your sustainable aerobic maximum.

Use a Powerbreathe or practice breathing with the bottom half of your
lungs - that's where the major oxygen absorption takes place.

Study the nutrition required. Also use a protien/mineral/vitamin drink
after training (within 20 minutes) to aid recovery and build muscle.

Training is good, but you can train until your eyeballs fall out and
be very slow unless you pay attention to details and ride smart. Age
and treachery etc...!!

But a flashy aero bike can intimidate the other riders!:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=270121944219

--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

On Sat, 26 May 2007 10:21:11 -0500, A Muzi <[email hidden]>

Quoted message said:

But a flashy aero bike can intimidate the other riders!:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=270121944219

Dear Andrew,

Same small front wheel TT scheme, but even more intimidating:

http://www.metzbicyclemuseum.com/Bike3a.html

The treadle drive fairly screams unfair high-tech advantage.

Cheers,

Carl Fogel

A Muzi said:

Quoted message said:

Quoted message said:

> <[email hidden]> wrote:

-Time trial improvement?-

Quoted message said:

Quoted message said:

>> [email hidden] wrote:
>>> Dude, rather than waste time with a skin suit and aero wheels, why
>>> don't you cut to the chase and dope? Plus, later on you can admit it
>>> (suggestion: publicly and tearfully) and everyone will think you're a
>>> real somebody.

lightninglad said:

Ignore the naysayers - I'm on your side. Ride smart!

Quoted message said:

Aero wheels will up your average at least 2 kph (based on my
experience with a 50mm Mavic Carbone.) A 10 minute gain per 40 kms is
the expected 'standard.' Put the best tyres on them that you can
afford (the new tubeless Hutchinson looks good) and fine tune the
pressure for the surface you're riding on. If it's a bit rough, a
slightly lower pressure will be faster.
If you can afford ceramic wheel bearings you'll gain a bit more. Ditto
with the BB and also get oversized and ceramic bearing jockey wheels.

Quoted message said:

Another big dragger is the helmet - a Chronos or similar time trial
helmet will make a noticeable difference.

Quoted message said:

Lightweight cranks and pedals will add a little and conserve your
energy. Carbon soled shoes are a must to maximise the power.

Quoted message said:

I have no idea what a skinsuit will do but I know that a half open
jacket gives noticeable drag - so I'd expect 1/2 to 1 kph minimum.

Quoted message said:

Tune your tuck position by finding a long hill and measuring your
maximum speed in various positions.

Quoted message said:

Do yourself a Conconi test to find your sustainable aerobic maximum.

Quoted message said:

Use a Powerbreathe or practice breathing with the bottom half of your
lungs - that's where the major oxygen absorption takes place.

Quoted message said:

Study the nutrition required. Also use a protien/mineral/vitamin drink
after training (within 20 minutes) to aid recovery and build muscle.

Quoted message said:

Training is good, but you can train until your eyeballs fall out and
be very slow unless you pay attention to details and ride smart. Age
and treachery etc...!!

But a flashy aero bike can intimidate the other riders!:http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=270121944219

--
Andrew Muziwww.yellowjersey.org
Open every day since 1 April, 1971

My funny bike needs a little TLC before it's ready to intimidate
anyone:

http://arbitrary.org/funny.jpg

Joseph