Zipp 303 vs 404

Don't forget durability and repairability. This isn't so much of an issue in TTs where you can spot
pot holes and such like a mile off, but in a road race you might not see a hole in the road until
it's too late. The 303s have more spokes (I think) and while this makes them less aerodynamic it
also makes them a lot easier to true.

Personally, I'd go for 303 then, if the time trialling really bothers you, save up for a more aero
wheelset later...

Chris

Montymobile <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

I'm considering getting a set of Zipps for road racing and some time trialing. Can anyone give me
any personal experiential insight on the pros and cons of each set - obviously the 303s are
lighter and the 404s are more aerodynamic but how much moe efficient are the 404s and how much
more are they affected by crosswinds etc. Graham

I would look at the American Classic 420s. A bit heavier (though not much), but cheaper and a lot
easier to repair. You also have more build options. Who wants to fool around with CF rims? Not me.

"Montymobile" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

I'm considering getting a set of Zipps for road racing and some time trialing. Can anyone give me
any personal experiential insight on the pros and cons of each set - obviously the 303s are
lighter and the 404s are more aerodynamic but how much moe efficient are the 404s and how much
more are they affected by crosswinds etc. Graham

The AC 420 isn't like a Ksyrium. The AC is 34 mm deep.

M

Andy Coggan said:

Based on its Ksyrium-like profile, I suspect that the AC 420 wouldn't be much more aerodynamic
than a standard box-section rim.

Andy Coggan

"Chris M" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

I would look at the American Classic 420s. A bit heavier (though not

much),

Quoted message said:

but cheaper and a lot easier to repair. You also have more build options. Who wants to fool
around with CF rims? Not me.

"Montymobile" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

I'm considering getting a set of Zipps for road racing and some time trialing. Can anyone give
me any personal experiential insight on the pros and cons of each set - obviously the 303s are
lighter and the 404s are more aerodynamic but how much moe efficient are the 404s and how much
more are they affected by crosswinds etc. Graham

Andy Coggan said:

Based on its Ksyrium-like profile, I suspect that the AC 420 wouldn't be much more aerodynamic
than a standard box-section rim.

The Ksyrium rims are 24mm deep in cross section. The AC420s are 34mm. Why don't you think there
would be a difference? The Zipp 303s are
40mm. I would say the AC420 is more Zipp-like than Ksyrium-like.

There's much more to rim aerodynamics than just depth.

Andy Coggan

"Michael Hoyt" <[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

The AC 420 isn't like a Ksyrium. The AC is 34 mm deep.

M

Andy Coggan said:

Based on its Ksyrium-like profile, I suspect that the AC 420 wouldn't be much more aerodynamic
than a standard box-section rim.

Andy Coggan

"Chris M" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

I would look at the American Classic 420s. A bit heavier (though not

much),

Quoted message said:

but cheaper and a lot easier to repair. You also have more build

options.

Quoted message said:

Quoted message said:

Quoted message said:

Who wants to fool around with CF rims? Not me.

"Montymobile" <[email hidden]> wrote in message
"]news:[email hidden]...
> I'm considering getting a set of Zipps for road racing and some time trialing. Can anyone
> give me any personal experiential insight on

the

Quoted message said:

Quoted message said:

Quoted message said:

> pros and cons of each set - obviously the 303s are lighter and the

404s

Quoted message said:

Quoted message said:

Quoted message said:

> are more aerodynamic but how much moe efficient are the 404s and how much more are they
> affected by crosswinds etc. Graham

"VeloCat" <[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

Andy Coggan said:

Based on its Ksyrium-like profile, I suspect that the AC 420 wouldn't be much more aerodynamic
than a standard box-section rim.

The Ksyrium rims are 24mm deep in cross section. The AC420s are 34mm. Why don't you think there
would be a difference? The Zipp 303s are
40mm. I would say the AC420 is more Zipp-like than Ksyrium-like.

Take a closer look:

amclassic.comRims.htmlOpen ↗

Given the squared-off inner circumference, I can't see the extra 10 mm of depth being all
that helpful.

Andy Coggan

Andy Coggan said:

"VeloCat" <[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

Andy Coggan said:

Based on its Ksyrium-like profile, I suspect that the AC 420 wouldn't be much more aerodynamic
than a standard box-section rim.

The Ksyrium rims are 24mm deep in cross section. The AC420s are 34mm. Why don't you think there
would be a difference? The Zipp 303s are
40mm. I would say the AC420 is more Zipp-like than Ksyrium-like.

Take a closer look:

amclassic.comRims.htmlOpen ↗

Given the squared-off inner circumference, I can't see the extra 10 mm of depth being all that
helpful.

Andy Coggan

While the Zipps have more of a bowed lateral surface, the inner circumference looks about as squared
off as the American Classics. The only cross section I can find is:

zipp.com303 clincher.htmlOpen ↗

I would think that there is some minimum flat area required for the spokes on the inner
circumference.

That's a picture of a 350. The 420 tapers to as fine an edge as you'll see on any wheel. I've seen
them in the flesh <g>.

M

Andy Coggan said:

"VeloCat" <[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

Andy Coggan said:

Based on its Ksyrium-like profile, I suspect that the AC 420 wouldn't be much more aerodynamic
than a standard box-section rim.

The Ksyrium rims are 24mm deep in cross section. The AC420s are 34mm. Why don't you think there
would be a difference? The Zipp 303s are
40mm. I would say the AC420 is more Zipp-like than Ksyrium-like.

Take a closer look:

amclassic.comRims.htmlOpen ↗

Given the squared-off inner circumference, I can't see the extra 10 mm of depth being all that
helpful.

Andy Coggan

"VeloCat" <[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

Andy Coggan said:

"VeloCat" <[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

Andy Coggan wrote:

>Based on its Ksyrium-like profile, I suspect that the AC 420 wouldn't

be

Quoted message said:

Quoted message said:

Quoted message said:

>much more aerodynamic than a standard box-section rim.
>

The Ksyrium rims are 24mm deep in cross section. The AC420s are 34mm. Why don't you think there
would be a difference? The Zipp 303s are
40mm. I would say the AC420 is more Zipp-like than Ksyrium-like.

Take a closer look:

amclassic.comRims.htmlOpen ↗

Given the squared-off inner circumference, I can't see the extra 10 mm

of

Quoted message said:

Quoted message said:

depth being all that helpful.

Andy Coggan

While the Zipps have more of a bowed lateral surface, the inner circumference looks about as
squared off as the American Classics. The only cross section I can find is:

zipp.com303 clincher.htmlOpen ↗

I would think that there is some minimum flat area required for the spokes on the inner
circumference.

I've looked at Zipp 303s, and own a Zipp 404 - there is no flat area like that found on the Kysrium
and AC 420 rims. (BTW, the "bowed" lateral surface of the Zipp is covered by a patent co-owned by
Hed and now Zipp, and is key to low drag when the wind comes at a slight angle).

As I responded to Michael Hoyt, there's more to rim aerodynamics than just depth, and I stand by my
prediction that the AC 420 is likely to more Kysrium-like than Zipp-like in its drag. (Kraig Willet
should be headed to the Texas A&M wind tunnel any day now...would be nice if we get an AC 420 wheel
to him to test.)

Andy Coggan

"Michael Hoyt" <[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

That's a picture of a 350. The 420 tapers to as fine an edge as you'll see

on

Quoted message said:

any wheel. I've seen them in the flesh <g>.

I was referring to the pictures of the 420 you'll find at the bottom of that page, which appear to
show the same squared-off inner circumference as found on the 350 rim (esp. the uncut rim shown on
the left). However, if the inner circumference is indeed rounded and not flat (and also not too
"pointy"😉, then the aerodynamics will be better than I first predicted.

Andy Coggan

Quoted message said:

Andy Coggan said:

"VeloCat" <[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

Andy Coggan wrote:
> Based on its Ksyrium-like profile, I suspect that the AC 420

wouldn't be

Quoted message said:

Quoted message said:

Quoted message said:

> much more aerodynamic than a standard box-section rim.
>

The Ksyrium rims are 24mm deep in cross section. The AC420s are 34mm. Why don't you think
there would be a difference? The Zipp 303s are
40mm. I would say the AC420 is more Zipp-like than Ksyrium-like.

Take a closer look:

amclassic.comRims.htmlOpen ↗

Given the squared-off inner circumference, I can't see the extra 10 mm

of

Quoted message said:

Quoted message said:

depth being all that helpful.

Andy Coggan

It sucks that AC won't offer the 420 rim for sale, they only offer it as a complete wheel. Are there
any other rims on the market, that have a similar depth, that you can buy just the rims alone (aside
from carbon rims from zipp)?

Andy Coggan said:

I was referring to the pictures of the 420 you'll find at the bottom of that page, which appear to
show the same squared-off inner circumference as found on the 350 rim (esp. the uncut rim shown on
the left). However, if the inner circumference is indeed rounded and not flat (and also not too
"pointy"😉, then the aerodynamics will be better than I first predicted.

Andy Coggan

I have my new AC420 in my hand and can say that the inner circumference is somewhat rounded,
definitely not flat. The cross section at

amclassic.comRims.htmlOpen ↗

is a pretty good representation. The outside surface of the rim along the inner circumference is
rounded, the "inside" (inside the rim itself) surface around the inner circumference appears flat in
the cross section. I believe this is visibile on the page sited above.

The Velocity Deep V is 30 mm deep, has a nicely rounded inner circumference, and pretty good
aerodynamics all things considered (based on wind tunnel tests of the original Rolf wheel, which
used the same rim). Compared to the 420, though, it isn't quite as deep (although again, just
based on the pics, I don't think the AC would necessarily generate any less drag), and it is about
100 g heavier.

Andy Coggan

"Kevin" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

It sucks that AC won't offer the 420 rim for sale, they only offer it as a complete wheel. Are
there any other rims on the market, that have a similar depth, that you can buy just the rims
alone (aside from carbon rims from zipp)?

"Andy Coggan" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

(Kraig Willet should be headed to the Texas A&M wind tunnel any day now...would be nice if we get
an AC 420 wheel to him to test.)

I head out Sunday. No such luck in this case though - I won't be testing the AC420.

The trailing edge, and rim curvature near it, does matter. I can remember testing a 47 mm deep rim
that was so inefficiently shaped that it performed equivalently to a 25 mm deep rim.

For the most part, though, (and I hate to generalize like this) rim depth is the primary contributor
to the reduction in body axis drag.

Anyone wishing to read more on the topic can email me privately for the Greenwell paper (a wheel
aerodynamics article that appeared in a scholarly journal).

--
==================
Kraig Willett www.biketechreview.com
==================

Andy Coggan said:

The Velocity Deep V is 30 mm deep, has a nicely rounded inner circumference, and pretty good
aerodynamics all things considered (based on wind tunnel tests of the original Rolf wheel, which
used the same rim). Compared to the 420, though, it isn't quite as deep (although again, just
based on the pics, I don't think the AC would necessarily generate any less drag), and it is about
100 g heavier.

Andy Coggan

Actually, I believe the original Rolf Wheels used the Araya SuperAero rim, which was also 30mm deep
but had a more rounded profile than the Velocity Deep V rim (and was a little lighter as well).

Mark McMaster [email hidden]

Quoted message said:

"Kevin" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

It sucks that AC won't offer the 420 rim for sale, they only offer it as a complete wheel. Are
there any other rims on the market, that have a similar depth, that you can buy just the rims
alone (aside from carbon rims from zipp)?

"Kraig Willett" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

"Andy Coggan" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

(Kraig Willet should be headed to the Texas A&M wind tunnel any day now...would be nice if we
get an AC

420

Quoted message said:

Quoted message said:

wheel to him to test.)

I head out Sunday.

Have fun! (And make sure you try that burrito place on the other side of campus.)

Quoted message said:

No such luck in this case though - I won't be testing the AC420.

That's too bad - if my guess proved incorrect and they were better aerodynamically than I expect,
then I would probably buy a set.

Quoted message said:

The trailing edge, and rim curvature near it, does matter. I can remember testing a 47 mm deep rim
that was so inefficiently shaped that it

performed

Quoted message said:

equivalently to a 25 mm deep rim.

Would that have been a LEW wheel perhaps?

Quoted message said:

For the most part, though, (and I hate to generalize like this) rim depth is the primary
contributor to the reduction in body axis drag.

Anyone wishing to read more on the topic can email me privately for the Greenwell paper (a wheel
aerodynamics article that appeared in a scholarly journal).

The Greenwell paper is getting a bit dated by now...maybe you should try writing up your results and
submitting them to a journal.

Andy Coggan

"Andy Coggan" <[email hidden]> wrote in message
news:<[email hidden]>...

Quoted message said:

The Velocity Deep V is 30 mm deep, has a nicely rounded inner circumference, and pretty good
aerodynamics all things considered (based on wind tunnel tests of the original Rolf wheel, which
used the same rim). Compared to the 420, though, it isn't quite as deep (although again, just
based on the pics, I don't think the AC would necessarily generate any less drag), and it is about
100 g heavier.

Andy,

The AC420 rim is rounded at the leading (or inner) edge, similar to the Deep V. The AC420 wheels are
pretty similar to Shamals.

-Amit

"Mark McMaster" <[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

Andy Coggan said:

The Velocity Deep V is 30 mm deep, has a nicely rounded inner

circumference,

Quoted message said:

Quoted message said:

and pretty good aerodynamics all things considered (based on wind tunnel tests of the original
Rolf wheel, which used the same rim). Compared to

the

Quoted message said:

Quoted message said:

420, though, it isn't quite as deep (although again, just based on the

pics,

Quoted message said:

Quoted message said:

I don't think the AC would necessarily generate any less drag), and it

is

Quoted message said:

Quoted message said:

about 100 g heavier.

Andy Coggan

Actually, I believe the original Rolf Wheels used the Araya SuperAero rim, which was also
30mm deep but had a more rounded profile than the Velocity Deep V rim (and was a little
lighter as well).

Now that you mention it, I believe you are right (as it was partially the thinness of the Araya rim
that led to lumpiness problems with the original Rolfs). Looking at the published cross-sections,
though, I couldn't tell a difference between the Araya and the Deep V, which is why I went with the
latter for that set of "do it all" wheels I built a few years ago.

Andy Coggan

"Amit" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

"Andy Coggan" <[email hidden]> wrote in message

news:<[email hidden]>...

Quoted message said:

Quoted message said:

The Velocity Deep V is 30 mm deep, has a nicely rounded inner

circumference,

Quoted message said:

Quoted message said:

and pretty good aerodynamics all things considered (based on wind tunnel tests of the original
Rolf wheel, which used the same rim). Compared to

the

Quoted message said:

Quoted message said:

420, though, it isn't quite as deep (although again, just based on the

pics,

Quoted message said:

Quoted message said:

I don't think the AC would necessarily generate any less drag), and it

is

Quoted message said:

Quoted message said:

about 100 g heavier.

Andy,

The AC420 rim is rounded at the leading (or inner) edge, similar to the Deep V. The AC420 wheels
are pretty similar to Shamals.

So now I'm really confused! The picture of the uncut rim makes it look rather "flat faced" (an
optical illusion, perhaps?), the picture of the cut rim looks a bit more rounded as you describe,
but then you compare the wheels to Shamals, which actually have a very sharp, or V-shaped, inner
circumference. Maybe the latter comparison is just in terms of rim material and depth?

Guess I'm going to have keep my eyes out for an AC420 in real life...

Andy Coggan