Deep dish aero wheels vs conventional racing wheels:(Tech Talk: Bontrager and the importance of bein

[[email protected]]

Deep dish aero wheels vs conventional racing wheelsTech Talk:
Bontrager and the importance of being aero')....??

(http://www.velonews.com/tech/report/articles/9797.0.html )

This discusses aero spoked carbon wheels like the Bontrager Aeouls.
This is not big news, what is interesting is that Discovery is using
these wheels for mountain stages as well. The idea is that they will
be more advantageous on the approach and leaving the col's. This
assumes that the stage is not all climbing. Now descents would be a bit
more tricky, since I don't believe that the braking issue has been
solved with a carbon surface.

 

[Qui si parla Campagnolo]

[email protected] wrote:
> Deep dish aero wheels vs conventional racing wheelsTech Talk:
> Bontrager and the importance of being aero')....??
>
> (http://www.velonews.com/tech/report/articles/9797.0.html )
>
> This discusses aero spoked carbon wheels like the Bontrager Aeouls.
> This is not big news, what is interesting is that Discovery is using
> these wheels for mountain stages as well. The idea is that they will
> be more advantageous on the approach and leaving the col's. This
> assumes that the stage is not all climbing. Now descents would be a bit
> more tricky, since I don't believe that the braking issue has been
> solved with a carbon surface.

Or how a gusty day will tend to blow the rider around, particularly the
front wheel. If it's windy, gonna be interesting around other riders.

 

[[email protected]]

[email protected] wrote:
> Deep dish aero wheels vs conventional racing wheelsTech Talk:
> Bontrager and the importance of being aero')....??
>
> (http://www.velonews.com/tech/report/articles/9797.0.html )
>
> This discusses aero spoked carbon wheels like the Bontrager Aeouls.
> This is not big news, what is interesting is that Discovery is using
> these wheels for mountain stages as well. The idea is that they will
> be more advantageous on the approach and leaving the col's. This
> assumes that the stage is not all climbing. Now descents would be a bit
> more tricky, since I don't believe that the braking issue has been
> solved with a carbon surface.

Is this really that new? I don't read this as trading weight for aero
as much as I read it as they are building a lightweight aero wheel,
which seems like the logical convergence of carbon fiber and
aerodynamics technology. I think the message is that for the fastest
cycling on hilly terrain you need light carbon aero rims with a
moderate depth.

I also found this interesting:

"Racing in Europe has influenced Bontrager's designs in a number of
ways. One of the most resounding is the use of a 22mm wide rim.

"On a tubular it gives us more gluing area, it also gives a bigger bed
to hold the tire," Balmer said. "It gives the tire a better profile as
it goes to the ground, particularly on a clincher, because your rim
width definitely influences your tire shape. A wider rim will change
that contact patch significantly."

What do they see as the advantage of more gluing area? Reduced squirm
and therefore lower rolling resistance? Or merely less chance of losing
a tire? It also sounds like the change in the contact patch may have
the result of lowering rolling resistance for clinchers. As I've
suggested before, I think the pros have more data on some of these
issues than we think we do here.

 

[[email protected]]

Jan and I believe Lance used them in some mountain stages. A lot of
riders used the deep dish aero wheels on flat stages. I am suprised
that the wind is not more of a issue. Years ago I remember climbing
this one hill and the wind forced me all the over to one side of the
road. I hate to think what would have happened with these aero wheels.
Qui si parla Campagnolo wrote:
> [email protected] wrote:
> > Deep dish aero wheels vs conventional racing wheelsTech Talk:
> > Bontrager and the importance of being aero')....??
> >
> > (http://www.velonews.com/tech/report/articles/9797.0.html )
> >
> > This discusses aero spoked carbon wheels like the Bontrager Aeouls.
> > This is not big news, what is interesting is that Discovery is using
> > these wheels for mountain stages as well. The idea is that they will
> > be more advantageous on the approach and leaving the col's. This
> > assumes that the stage is not all climbing. Now descents would be a bit
> > more tricky, since I don't believe that the braking issue has been
> > solved with a carbon surface.
>
> Or how a gusty day will tend to blow the rider around, particularly the
> front wheel. If it's windy, gonna be interesting around other riders.

 

[Donald Munro]

Qui si parla Campagnolo wrote:
>> Or how a gusty day will tend to blow the rider around, particularly the
>> front wheel. If it's windy, gonna be interesting around other riders.

hizark21 wrote:

> Jan and I believe Lance used them in some mountain stages. A lot of
> riders used the deep dish aero wheels on flat stages. I am suprised
> that the wind is not more of a issue. Years ago I remember climbing
> this one hill and the wind forced me all the over to one side of the

Perhaps for wheels with solid spokes, but I've used Mavic Cosmic's in some
pretty strong winds without to many problems.

 

[Ron Ruff]

[email protected] wrote:

> "Racing in Europe has influenced Bontrager's designs in a number of
> ways. One of the most resounding is the use of a 22mm wide rim.

I've been wondering about that for some time, since an aero rim
generally needs to be within 2mm of the tire width to function well...
but rims are usually 19mm and tires are 23-24mm in road races. 22mm
makes a lot of sense.

 

[Carl Sundquist]

<[email protected]> wrote in message
news:[email protected]...
>
> I also found this interesting:
>
> "Racing in Europe has influenced Bontrager's designs in a number of
> ways. One of the most resounding is the use of a 22mm wide rim.
>
> "On a tubular it gives us more gluing area, it also gives a bigger bed
> to hold the tire," Balmer said. "It gives the tire a better profile as
> it goes to the ground, particularly on a clincher, because your rim
> width definitely influences your tire shape. A wider rim will change
> that contact patch significantly."
>
> What do they see as the advantage of more gluing area? Reduced squirm
> and therefore lower rolling resistance? Or merely less chance of losing
> a tire? It also sounds like the change in the contact patch may have
> the result of lowering rolling resistance for clinchers. As I've
> suggested before, I think the pros have more data on some of these
> issues than we think we do here.
>

How is the contact patch changed? As long as the tires compress even
slightly, the size of the contact patch is going to be a function of weight
on the wheel / psi regardless of the width of the tire. With a wider rim the
_casing_ may deform less (decreasing rolling resistance), but that has no
bearing on the contact patch itself.

 

[Chalo]

Carl Sundquist wrote:
>
> How is the contact patch changed? As long as the tires compress even
> slightly, the size of the contact patch is going to be a function of weight
> on the wheel / psi regardless of the width of the tire. With a wider rim the
> _casing_ may deform less (decreasing rolling resistance), but that has no
> bearing on the contact patch itself.

The _average_ load on the contact patch is simply a function of
pressure, but every contact patch has a pressure gradient across it
from zero at the edge to some maximum value at or near the center. I
expect that the more uniformly the contact patch is loaded, the more
traction it will be able to provide, and the more positively it will
provide camber thrust when leaned. My speculation is in principle and
does not address the particular wheel at issue, which I know nothing
about.

Chalo

 

[Robert Chung]

Carl Sundquist wrote:
>
> How is the contact patch changed? As long as the tires compress even
> slightly, the size of the contact patch is going to be a function of
> weight on the wheel / psi regardless of the width of the tire.

The area of the contact patch doesn't change but the aspect ratio can.

 

[Carl Sundquist]

"Robert Chung" <[email protected]> wrote in message
news:[email protected]...
> Carl Sundquist wrote:
>>
>> How is the contact patch changed? As long as the tires compress even
>> slightly, the size of the contact patch is going to be a function of
>> weight on the wheel / psi regardless of the width of the tire.
>
> The area of the contact patch doesn't change but the aspect ratio can.
>

Then Balmer should have said aspect ratio. FWIW, I agree with you. However,
as I see it, changing the aspect ratio is akin to squaring off the tire,
which would make it less responsive in turns.

 

[Booker C. Bense]

-----BEGIN PGP SIGNED MESSAGE-----

In article <[email protected]>,
Michael Press <[email protected]> wrote:
>In article
><[email protected]>,
> Dave Larrington <[email protected]> wrote:
>
>>
>> One explanation I have seen advanced is that rolling resistance depends
>> on the /circumference/ of the contact patch. The closer to circular the
>> patch, the shorter the circumference. All other things being equal
>> (which natch, they never are) the tyre with the least rolling resistance
>> would be a sphere.
>
>Rolling resistance depends on two things.
>
>1. Tire tread. The more tread, the more resistance. The
>energy is dissipated in deforming the tread.
>
>2. Side wall flex. The stiffer and thicker the side wall,
>the more resistance. Energy is dissipated bending the side
>wall.
>

You've described the mechanisms, but not how to minimize
them. Since the tire flexes at the circumference of the
contact patch, minimizing that circumference to minimize
RR seems to at least be consistant. Although after some
thought I think that you'd want to minimize the edge
length in the direction of the highest curvature.
(ie. shorter and wider is faster than long and skinny ).

_ Booker C. Bense


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[Michael Press]

In article <[email protected]>,
Booker C. Bense
<bbense+rec.bicycles.tech.rec.bicycles.racing.May.03.06@t
elemark.slac.stanford.edu> wrote:

> -----BEGIN PGP SIGNED MESSAGE-----
>
> In article <[email protected]>,
> Michael Press <[email protected]> wrote:
> >In article
> ><[email protected]>,
> > Dave Larrington <[email protected]> wrote:
> >
> >>
> >> One explanation I have seen advanced is that rolling resistance depends
> >> on the /circumference/ of the contact patch. The closer to circular the
> >> patch, the shorter the circumference. All other things being equal
> >> (which natch, they never are) the tyre with the least rolling resistance
> >> would be a sphere.
> >
> >Rolling resistance depends on two things.
> >
> >1. Tire tread. The more tread, the more resistance. The
> >energy is dissipated in deforming the tread.
> >
> >2. Side wall flex. The stiffer and thicker the side wall,
> >the more resistance. Energy is dissipated bending the side
> >wall.
> >
>
> You've described the mechanisms, but not how to minimize
> them. Since the tire flexes at the circumference of the
> contact patch, minimizing that circumference to minimize
> RR seems to at least be consistant. Although after some
> thought I think that you'd want to minimize the edge
> length in the direction of the highest curvature.
> (ie. shorter and wider is faster than long and skinny ).

Up to a point. There are conflicting effects. Wider tire
requires lower air pressure. Lower air pressure means more
side wall flex. Very high pressure increases energy
dissipation by way of road bounce.

Contact patch geometry may be correlated with rolling
resistance (or not; I do not know). Contact patch geometry
does not cause rolling resistance; this I do know. Side
wall flex causes rolling resistance. Side wall flex is an
invariant. It occurs at the contact patch and it is the
change in the shape of the side wall that supports the
rim.

Here are tire design criteria for reducing rolling
resistance.

1. Slick tread. No channels, lumps, knurling, or cuts.

2. Thin side wall; high thread count; thin threads.
Beware of tire manufacturers that misrepresent the thread
count.

3. No belts for puncture resistance.

4. Thin tread.

Interestingly, designing a tire for decreased rolling
resistance also improves its cornering.

Ultimately, marginal reductions in rolling resistance will
not be worth the price paid in other areas according to
one's own economy. (puncture resistance, off road, price,
....)

--
Michael Press

 

[Matt O'Toole]

On Mon, 01 May 2006 18:50:10 -0700, hizark21 wrote:

> Deep dish aero wheels vs conventional racing wheelsTech Talk:
> Bontrager and the importance of being aero')....??
>
> (http://www.velonews.com/tech/report/articles/9797.0.html )
>
> This discusses aero spoked carbon wheels like the Bontrager Aeouls.
> This is not big news, what is interesting is that Discovery is using
> these wheels for mountain stages as well. The idea is that they will
> be more advantageous on the approach and leaving the col's. This
> assumes that the stage is not all climbing. Now descents would be a bit
> more tricky, since I don't believe that the braking issue has been
> solved with a carbon surface.

Aero wheels have more room for logos!

Matt O.

 

[Mike Reed]

Michael Press wrote:
> In article <[email protected]>,
> Booker C. Bense
> <bbense+rec.bicycles.tech.rec.bicycles.racing.May.03.06@t
> elemark.slac.stanford.edu> wrote:
>
> > -----BEGIN PGP SIGNED MESSAGE-----
> >
> > In article <[email protected]>,
> > Michael Press <[email protected]> wrote:
> > >In article
> > ><[email protected]>,
> > > Dave Larrington <[email protected]> wrote:
> > >
> > >>
> > >> One explanation I have seen advanced is that rolling resistance depends
> > >> on the /circumference/ of the contact patch. The closer to circular the
> > >> patch, the shorter the circumference. All other things being equal
> > >> (which natch, they never are) the tyre with the least rolling resistance
> > >> would be a sphere.
> > >
> > >Rolling resistance depends on two things.
> > >
> > >1. Tire tread. The more tread, the more resistance. The
> > >energy is dissipated in deforming the tread.
> > >
> > >2. Side wall flex. The stiffer and thicker the side wall,
> > >the more resistance. Energy is dissipated bending the side
> > >wall.
> > >
> >
> > You've described the mechanisms, but not how to minimize
> > them. Since the tire flexes at the circumference of the
> > contact patch, minimizing that circumference to minimize
> > RR seems to at least be consistant. Although after some
> > thought I think that you'd want to minimize the edge
> > length in the direction of the highest curvature.
> > (ie. shorter and wider is faster than long and skinny ).
>
> Up to a point. There are conflicting effects. Wider tire
> requires lower air pressure. Lower air pressure means more
> side wall flex. Very high pressure increases energy
> dissipation by way of road bounce.

Except in this subthread, we're talking about changing the contact
patch shape only by modifying bead width. Tire pressure would remain
unchanged.

-Mike

 

[Carl Sundquist]

"Mike Reed" <[email protected]> wrote in message
news:[email protected]...
>
> Except in this subthread, we're talking about changing the contact
> patch shape only by modifying bead width. Tire pressure would remain
> unchanged.
>

Wouldn't changing the contact patch shape in this manner (I assume it to be
more round, not as elliptical) also increase the risk of rim related
punctures?

 

[Mike Reed]

Carl Sundquist wrote:
> "Mike Reed" <[email protected]> wrote in message
> news:[email protected]...
> >
> > Except in this subthread, we're talking about changing the contact
> > patch shape only by modifying bead width. Tire pressure would remain
> > unchanged.
> >
>
> Wouldn't changing the contact patch shape in this manner (I assume it to be
> more round, not as elliptical) also increase the risk of rim related
> punctures?

Tough to say. It depends on how the tire profile changes as the rim
widens. For the first few mm of increase, I'd think that the
rim-to-ground distance would actually go up, since the sidewalls will
exit the rim at a near-parallel angle. If you have a greater
rim-to-ground distance with the same pressure, I'd think pinch flats
would be less likely.

-Mike

 

[Carl Sundquist]

"Mike Reed" <[email protected]> wrote in message
news:[email protected]...
>>
>> Wouldn't changing the contact patch shape in this manner (I assume it to
>> be
>> more round, not as elliptical) also increase the risk of rim related
>> punctures?
>
> Tough to say. It depends on how the tire profile changes as the rim
> widens. For the first few mm of increase, I'd think that the
> rim-to-ground distance would actually go up, since the sidewalls will
> exit the rim at a near-parallel angle. If you have a greater
> rim-to-ground distance with the same pressure, I'd think pinch flats
> would be less likely.
>
> -Mike
>

True that the sidewalls would exit the rim at a near parallel angle, but I
don't know if that would automatically increase the rim to ground distance,
as mentioned elsewhere, the aspect ratio would likely change also.

 

[Mike Reed]

Carl Sundquist wrote:
> "Mike Reed" <[email protected]> wrote in message
> news:[email protected]...
> >>
> >> Wouldn't changing the contact patch shape in this manner (I assume it to
> >> be
> >> more round, not as elliptical) also increase the risk of rim related
> >> punctures?
> >
> > Tough to say. It depends on how the tire profile changes as the rim
> > widens. For the first few mm of increase, I'd think that the
> > rim-to-ground distance would actually go up, since the sidewalls will
> > exit the rim at a near-parallel angle. If you have a greater
> > rim-to-ground distance with the same pressure, I'd think pinch flats
> > would be less likely.
> >
> > -Mike
> >
>
> True that the sidewalls would exit the rim at a near parallel angle, but I
> don't know if that would automatically increase the rim to ground distance,
> as mentioned elsewhere, the aspect ratio would likely change also.

Yep. I think we're all doing a lot of speculation here

 

[Jasper Janssen]

On Tue, 2 May 2006 19:54:10 -0500, "Carl Sundquist" <[email protected]>
wrote:

>How is the contact patch changed? As long as the tires compress even
>slightly, the size of the contact patch is going to be a function of weight
>on the wheel / psi regardless of the width of the tire. With a wider rim the
>_casing_ may deform less (decreasing rolling resistance), but that has no
>bearing on the contact patch itself.

The *shape* of the contact patch changes, not the size.

Jasper

 

[Carl Sundquist]

"Jasper Janssen" <[email protected]> wrote in message
news:[email protected]...
> On Tue, 2 May 2006 19:54:10 -0500, "Carl Sundquist" <[email protected]>
> wrote:
>
>>How is the contact patch changed? As long as the tires compress even
>>slightly, the size of the contact patch is going to be a function of
>>weight
>>on the wheel / psi regardless of the width of the tire. With a wider rim
>>the
>>_casing_ may deform less (decreasing rolling resistance), but that has no
>>bearing on the contact patch itself.
>
> The *shape* of the contact patch changes, not the size.
>

Ok, will that enhance performance?