Solid carbon disk wheel vs Campagnolo kevlar Ghibli disk wheels

Quoted message said:

I have noticed that in recent year more riders are using the solid
carbon fiber disc wheels as opposed the Campagnolo Ghibli. Does anyone
know the advantages and disadvantages
other than the sinusoidal benefits that the Ghibli disc's have. My
guess is that since the Ghibli is made of kevlar there is some loss of
energy since they flex more.

Shane Kelly (4 kilo world championships) and the Australian track
contingent have been using them with great success for years.

I would gather that it all comes down to sponsorship and cost.

Interestingly, in the early 90's after the end of the Cold War you
could buy the Russian made version astonishingly cheaply. Like less
than $200. They were similar to both the Campy discs and the Falcon
Accel discs whereby a skin was bonded to the rim and hub, rather than
carbon over a foam core. On the Russian discs, the hub shell was
threaded so that (in manufacturing the wheel)it could be rotated
against the flanges. This caused the flanges to move outward on the
hub, tensioning the Kevlar skin. Then the flanges were bonded into
place on the hub. I would assume the Kevlar received an epoxy treatment
after tensioning, rather than before.

The problem with the wheels was that their quality control wasn't very
good. The interface of the kevlar to the rim was rough, and sometimes
the tensioning wasn't uniform enough to make an especially true wheel.
Perhaps the Kevlar fabric wasn't exactly even between the hub and rim
all the way around the wheel. It also seems like the trueness degraded
with time, which doesn't make sense. But the darn things were light
though.

I don't think cost is a issue. Sponorship plays a factor, but I have
noticed that in many cases a rider will use a different brand than
what the team normally uses. The big difference I have noticed is that
more riders are using disks that have a flat rather than a convex
surface. In the end I think it boils down to technical advantage. I
have not compared the weights recently, but I am sure that is a major
consideration.

Quoted message said:

I don't think cost is a issue. Sponorship plays a factor, but I have
noticed that in many cases a rider will use a different brand than
what the team normally uses. The big difference I have noticed is that
more riders are using disks that have a flat rather than a convex
surface. In the end I think it boils down to technical advantage. I
have not compared the weights recently, but I am sure that is a major
consideration.

Based on more than decade old information, I was under the impression
that a lenticular shape performed slightly better than flat. From what
I gleaned on a quick google search is that the difference in drag
between flat and lens is less than the margin of error, but a lens
shape may provide slightly better handling characteristics in side
winds.

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

Quoted message said:

Quoted message said:

I don't think cost is a issue. Sponorship plays a factor, but I have
noticed that in many cases a rider will use a different brand than
what the team normally uses. The big difference I have noticed is that
more riders are using disks that have a flat rather than a convex
surface. In the end I think it boils down to technical advantage. I
have not compared the weights recently, but I am sure that is a major
consideration.

Based on more than decade old information, I was under the impression
that a lenticular shape performed slightly better than flat. From what
I gleaned on a quick google search is that the difference in drag
between flat and lens is less than the margin of error, but a lens
shape may provide slightly better handling characteristics in side
winds.

Yes, but then compare weights of, say, a HED lenticular (or even their
"superlight" version) to a Renn 575. The Renn is a good bit lighter.
Wonder if that wouldn't pretty much negate what little advantage would be
gained from a lenticular shape. (Don't have the weights on Zipp disk wheels
handy, but when you're talking about a wheel that costs almost $1,000 more
than a Renn 575 ... well, that's not in my reality.)
--
Bob C.

"Of course it hurts. The trick is not minding that it hurts."
T. E. Lawrence (of Arabia)

psycholist said:

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

Quoted message said:

Quoted message said:

I don't think cost is a issue. Sponorship plays a factor, but I have
noticed that in many cases a rider will use a different brand than
what the team normally uses. The big difference I have noticed is that
more riders are using disks that have a flat rather than a convex
surface. In the end I think it boils down to technical advantage. I
have not compared the weights recently, but I am sure that is a major
consideration.

Based on more than decade old information, I was under the impression
that a lenticular shape performed slightly better than flat. From what
I gleaned on a quick google search is that the difference in drag
between flat and lens is less than the margin of error, but a lens
shape may provide slightly better handling characteristics in side
winds.

Yes, but then compare weights of, say, a HED lenticular (or even their
"superlight" version) to a Renn 575. The Renn is a good bit lighter.
Wonder if that wouldn't pretty much negate what little advantage would be
gained from a lenticular shape. (Don't have the weights on Zipp disk wheels
handy, but when you're talking about a wheel that costs almost $1,000 more
than a Renn 575 ... well, that's not in my reality.)

The Renn 575 is probably lighter, but its flat carbon sides are
significantly recessed from the sides of the aluminum rim, which
would seem to be bad aerodynamically. I suspect this is because the
honeycomb core the Renn uses is not available in the exact thickness
they need, so they use the next smaller thickness. The HED has a smooth
transition from the rim side to the disk. I haven't seen any tests
comparing drag of these two disks.

Dave Lehnen

On 12 Sep 2005 04:25:08 -0700, "Carl Sundquist" <[email hidden]>

Quoted message said:

Quoted message said:

I don't think cost is a issue. Sponorship plays a factor, but I have
noticed that in many cases a rider will use a different brand than
what the team normally uses. The big difference I have noticed is that
more riders are using disks that have a flat rather than a convex
surface. In the end I think it boils down to technical advantage. I
have not compared the weights recently, but I am sure that is a major
consideration.

Based on more than decade old information, I was under the impression
that a lenticular shape performed slightly better than flat. From what
I gleaned on a quick google search is that the difference in drag
between flat and lens is less than the margin of error, but a lens
shape may provide slightly better handling characteristics in side
winds.

Interaction with the frame also enters the equation - British Cycling
decided a lenticular disc worked better on their track frame, if only
by a very small margin, but I expect everybody else is doing the same
kind of wind tunnel work and some choose parallel sided discs. I also
read recently in an interview with Steve Hed

" As bike design is changing, as aero seat-stays and aero seat-tubes
are changing, a disc wheel is probably not the best wheel for the
future anymore. I think a tri-spoke or some version of something
else... "

http://www.cyclingnews.com/road/2005/apr05/georgia05/tech/?id=/tech/2005/features/georgia_hed

Kinky Cowboy*

*Batteries not included
May contain traces of nuts
Your milage may vary