On the virtue of traditional wheels when racing Paris-Roubaix

[[email protected]]

Nice Paris-Roubaix race this year where Tom Boonen got a deserved win.

Lots of 32 3X wheels and perhaps even 36 3X wheels at that race, only
a few of the potential contenders rode anything else;

Magnus Backstedt rode deep-section carbon wheels and broke both of
them:

"Swede Magnus Backstedt, felled by mechanical difficulties during the
race's 18th sector of pavé, the dreaded 2.4km slog through the forest
of Arenberg. Backstedt, the 2004 Roubaix winner, emerged from the
forest with two cracked deep-section carbon wheels. During the wheel
change, one of the Swede's brake pads slipped out of the caliper. He
remounted his rig and began riding, but soon required a complete bike
change and lost contact with the front of the race. He did not
finish."
http://www.velonews.com/article/74628/slipstream-s-maaskant-4th-into-roubaix


George Hincapie also rode deep-section carbon wheels (HED I believe)
and broke at least one of them:

"Second in 2005, but missing from the winning break this time, was an
unlucky George Hincapie (High Road). The tall American said he was
strong enough to have been with the winners until he ran into trouble.
He was riding at the front on the Bersée section of cobblestones, 53km
from the finish, and racing as well as he has ever ridden in the Hell
of the North, when his rear wheel broke. "I had great legs," Hincapie
said, "but there was nothing I could do." "
http://www.velonews.com/article/74625/boonen-wins-paris-roubaix

Of course this is only anecdotal "evidence" that low spoke count
carbon wheels isn't the best choice for a race like Paris-Roubaix,
still the main contender teams; CSC (Cancellera winner: 2006, O'Grady
2007) and Quick Step (Boonen 2005, 2008) seems to think so.

--
Regards

 

[André Tuytschaver]

[email protected] a écrit :
> Nice Paris-Roubaix race this year where Tom Boonen got a deserved win.
>
> Lots of 32 3X wheels and perhaps even 36 3X wheels at that race, only
> a few of the potential contenders rode anything else;
>
> Magnus Backstedt rode deep-section carbon wheels and broke both of
> them:

Backstedt won Paris-Roubaix in 2004 with aluminium "flat-section"
Neutron Campagnolo wheels...


--
Cordialement,
________________
@ndré

__o
_'\(,_
(_)/ (_)

 

[[email protected]]

On Apr 14, 1:17 pm, [email protected] wrote:
> Nice Paris-Roubaix race this year where Tom Boonen got a deserved win.
>
> Lots of 32 3X wheels and perhaps even 36 3X wheels at that race, only
> a few of the potential contenders rode anything else;
>
> Magnus Backstedt rode deep-section carbon wheels and broke both of
> them:
>
> "Swede Magnus Backstedt, felled by mechanical difficulties during the
> race's 18th sector of pavé, the dreaded 2.4km slog through the forest
> of Arenberg. Backstedt, the 2004 Roubaix winner, emerged from the
> forest with two cracked deep-section carbon wheels. During the wheel
> change, one of the Swede's brake pads slipped out of the caliper. He
> remounted his rig and began riding, but soon required a complete bike
> change and lost contact with the front of the race. He did not
> finish."http://www.velonews.com/article/74628/slipstream-s-maaskant-4th-into-...
>
> George Hincapie also rode deep-section carbon wheels (HED I believe)
> and broke at least one of them:
>
> "Second in 2005, but missing from the winning break this time, was an
> unlucky George Hincapie (High Road). The tall American said he was
> strong enough to have been with the winners until he ran into trouble.
> He was riding at the front on the Bersée section of cobblestones, 53km
> from the finish, and racing as well as he has ever ridden in the Hell
> of the North, when his rear wheel broke. "I had great legs," Hincapie
> said, "but there was nothing I could do." "http://www.velonews.com/article/74625/boonen-wins-paris-roubaix
>
> Of course this is only anecdotal "evidence" that low spoke count
> carbon wheels isn't the best choice for a race like Paris-Roubaix,
> still the main contender teams; CSC (Cancellera winner: 2006, O'Grady
> 2007) and Quick Step (Boonen 2005, 2008) seems to think so.
>
> --
> Regards

I'll say. A normal flat race would make sense to use deep section
wheels, as they are more than strong enough for that, and provide a
useful advantage. But Paris-Roubaix isn't a normal flat race. The
cobbles is where people get dropped, and there, despite insane speed,
it isn't wind resistance on the wheels that separates the men from the
boys. Given the prospect of having a race ruined by a broken wheel, vs
a few watts saved on the non-critical smooth sections, it's obvious to
me what wheels to choose. Big tires too like Ballan.

And a 90kg+ guy like Magnus using anything but extra strong wheels
seems foolish.

Joseph

 

[[email protected]]

On 14 Apr., 13:43, André Tuytschaver <[email protected]>
wrote:

> Backstedt won Paris-Roubaix in 2004 with aluminium "flat-section"
> Neutron Campagnolo wheels...

(My first answer seems to have disappeared, so I try again. Sorry if
this turns out to be a double post)

Sure, and the rookie Maaskent came in 4th on the same type of carbon
wheels that Hincapi broke.
I am not saying that carbon wheels can't be used for a race like PR,
just that they don't seem to be the best choice.
For to win a race you have to finish it.

--
Regards

 

[[email protected]]

On Apr 14, 8:35 am, "[email protected]"
<[email protected]> wrote:
> On Apr 14, 1:17 pm, [email protected] wrote:
>
>
>
> > Nice Paris-Roubaix race this year where Tom Boonen got a deserved win.
>
> > Lots of 32 3X wheels and perhaps even 36 3X wheels at that race, only
> > a few of the potential contenders rode anything else;
>
> > Magnus Backstedt rode deep-section carbon wheels and broke both of
> > them:
>
> > "Swede Magnus Backstedt, felled by mechanical difficulties during the
> > race's 18th sector of pavé, the dreaded 2.4km slog through the forest
> > of Arenberg. Backstedt, the 2004 Roubaix winner, emerged from the
> > forest with two cracked deep-section carbon wheels. During the wheel
> > change, one of the Swede's brake pads slipped out of the caliper. He
> > remounted his rig and began riding, but soon required a complete bike
> > change and lost contact with the front of the race. He did not
> > finish."http://www.velonews.com/article/74628/slipstream-s-maaskant-4th-into-...
>
> > George Hincapie also rode deep-section carbon wheels (HED I believe)
> > and broke at least one of them:
>
> > "Second in 2005, but missing from the winning break this time, was an
> > unlucky George Hincapie (High Road). The tall American said he was
> > strong enough to have been with the winners until he ran into trouble.
> > He was riding at the front on the Bersée section of cobblestones, 53km
> > from the finish, and racing as well as he has ever ridden in the Hell
> > of the North, when his rear wheel broke. "I had great legs," Hincapie
> > said, "but there was nothing I could do." "http://www.velonews.com/article/74625/boonen-wins-paris-roubaix
>
> > Of course this is only anecdotal "evidence" that low spoke count
> > carbon wheels isn't the best choice for a race like Paris-Roubaix,
> > still the main contender teams; CSC (Cancellera winner: 2006, O'Grady
> > 2007) and Quick Step (Boonen 2005, 2008) seems to think so.
>
> > --
> > Regards
>
> I'll say. A normal flat race would make sense to use deep section
> wheels, as they are more than strong enough for that, and provide a
> useful advantage. But Paris-Roubaix isn't a normal flat race. The
> cobbles is where people get dropped, and there, despite insane speed,
> it isn't wind resistance on the wheels that separates the men from the
> boys. Given the prospect of having a race ruined by a broken wheel, vs
> a few watts saved on the non-critical smooth sections, it's obvious to
> me what wheels to choose. Big tires too like Ballan.
>
> And a 90kg+ guy like Magnus using anything but extra strong wheels
> seems foolish.
>
> Joseph

I think it's just a matter of time before one of the wheel
manufacturers comes up with a batch of Roubaix special carbon wheels.
There's no reason why those deep carbon rims can't be strong enough to
handle the cobbles if enough material is added, and in a race where a
46 ring is "small" the extra weight won't be an issue. In addition to
aerodynamics, tall rims don't get sucked into deep mud as hard as box
sections.

 

[[email protected]]

On Apr 14, 6:27 pm, [email protected] wrote:
> On Apr 14, 8:35 am, "[email protected]"
>
>
>
> <[email protected]> wrote:
> > On Apr 14, 1:17 pm, [email protected] wrote:
>
> > > Nice Paris-Roubaix race this year where Tom Boonen got a deserved win.
>
> > > Lots of 32 3X wheels and perhaps even 36 3X wheels at that race, only
> > > a few of the potential contenders rode anything else;
>
> > > Magnus Backstedt rode deep-section carbon wheels and broke both of
> > > them:
>
> > > "Swede Magnus Backstedt, felled by mechanical difficulties during the
> > > race's 18th sector of pavé, the dreaded 2.4km slog through the forest
> > > of Arenberg. Backstedt, the 2004 Roubaix winner, emerged from the
> > > forest with two cracked deep-section carbon wheels. During the wheel
> > > change, one of the Swede's brake pads slipped out of the caliper. He
> > > remounted his rig and began riding, but soon required a complete bike
> > > change and lost contact with the front of the race. He did not
> > > finish."http://www.velonews.com/article/74628/slipstream-s-maaskant-4th-into-...
>
> > > George Hincapie also rode deep-section carbon wheels (HED I believe)
> > > and broke at least one of them:
>
> > > "Second in 2005, but missing from the winning break this time, was an
> > > unlucky George Hincapie (High Road). The tall American said he was
> > > strong enough to have been with the winners until he ran into trouble.
> > > He was riding at the front on the Bersée section of cobblestones, 53km
> > > from the finish, and racing as well as he has ever ridden in the Hell
> > > of the North, when his rear wheel broke. "I had great legs," Hincapie
> > > said, "but there was nothing I could do." "http://www.velonews.com/article/74625/boonen-wins-paris-roubaix
>
> > > Of course this is only anecdotal "evidence" that low spoke count
> > > carbon wheels isn't the best choice for a race like Paris-Roubaix,
> > > still the main contender teams; CSC (Cancellera winner: 2006, O'Grady
> > > 2007) and Quick Step (Boonen 2005, 2008) seems to think so.
>
> > > --
> > > Regards
>
> > I'll say. A normal flat race would make sense to use deep section
> > wheels, as they are more than strong enough for that, and provide a
> > useful advantage. But Paris-Roubaix isn't a normal flat race. The
> > cobbles is where people get dropped, and there, despite insane speed,
> > it isn't wind resistance on the wheels that separates the men from the
> > boys. Given the prospect of having a race ruined by a broken wheel, vs
> > a few watts saved on the non-critical smooth sections, it's obvious to
> > me what wheels to choose. Big tires too like Ballan.
>
> > And a 90kg+ guy like Magnus using anything but extra strong wheels
> > seems foolish.
>
> > Joseph
>
> I think it's just a matter of time before one of the wheel
> manufacturers comes up with a batch of Roubaix special carbon wheels.
> There's no reason why those deep carbon rims can't be strong enough to
> handle the cobbles if enough material is added, and in a race where a

I agree. And with all the special one-off bikes that are used, I'm
surprised the wheel manufacturers haven't already.


> 46 ring is "small" the extra weight won't be an issue.  In addition to
> aerodynamics, tall rims don't get sucked into deep mud as hard as box
> sections.

Is that why those wheels are used so often in cyclo-cross? I often
wondered why they are so prevalent.

Joseph

 

[Ryan Cousineau]

In article
<e58771[email protected]>,
"joseph.santani[email protected]" <[email protected]> wrote:

> On Apr 14, 6:27 pm, [email protected] wrote:
> > On Apr 14, 8:35 am, "[email protected]"
> >
> >
> >
> > <[email protected]> wrote:
> > > On Apr 14, 1:17 pm, [email protected] wrote:

> > I think it's just a matter of time before one of the wheel
> > manufacturers comes up with a batch of Roubaix special carbon wheels.
> > There's no reason why those deep carbon rims can't be strong enough to
> > handle the cobbles if enough material is added, and in a race where a
>
> I agree. And with all the special one-off bikes that are used, I'm
> surprised the wheel manufacturers haven't already.
>
>
> > 46 ring is "small" the extra weight won't be an issue.  In addition to
> > aerodynamics, tall rims don't get sucked into deep mud as hard as box
> > sections.
>
> Is that why those wheels are used so often in cyclo-cross? I often
> wondered why they are so prevalent.

I believe that's the theory, yes. After all, the aero considerations are
low, and the weight can't be any better than that of the best
low-profile rims.

Also, and never underestimate this factor, CX bikes with Zipp 404s look
way cool.

--
Ryan Cousineau [email protected] http://www.wiredcola.com/
"In other newsgroups, they killfile trolls."
"In rec.bicycles.racing, we coach them."

 

[Tom Sherman]

Ryan Cousineau wrote:
> [...]
> Also, and never underestimate this factor, CX bikes with Zipp 404s look
> way cool.
>
Does that opinion have the Fabrizio Mazzoleni seal of approval?

--
Tom Sherman - Holstein-Friesland Bovinia
The weather is here, wish you were beautiful

 

[[email protected]]

On Apr 14, 1:05 pm, "[email protected]"
<[email protected]> wrote:
> On Apr 14, 6:27 pm, [email protected] wrote:
>
>
>
> > On Apr 14, 8:35 am, "[email protected]"
>
> > <[email protected]> wrote:
> > > On Apr 14, 1:17 pm, [email protected] wrote:
>
> > > > Nice Paris-Roubaix race this year where Tom Boonen got a deserved win.
>
> > > > Lots of 32 3X wheels and perhaps even 36 3X wheels at that race, only
> > > > a few of the potential contenders rode anything else;
>
> > > > Magnus Backstedt rode deep-section carbon wheels and broke both of
> > > > them:
>
> > > > "Swede Magnus Backstedt, felled by mechanical difficulties during the
> > > > race's 18th sector of pavé, the dreaded 2.4km slog through the forest
> > > > of Arenberg. Backstedt, the 2004 Roubaix winner, emerged from the
> > > > forest with two cracked deep-section carbon wheels. During the wheel
> > > > change, one of the Swede's brake pads slipped out of the caliper. He
> > > > remounted his rig and began riding, but soon required a complete bike
> > > > change and lost contact with the front of the race. He did not
> > > > finish."http://www.velonews.com/article/74628/slipstream-s-maaskant-4th-into-...
>
> > > > George Hincapie also rode deep-section carbon wheels (HED I believe)
> > > > and broke at least one of them:
>
> > > > "Second in 2005, but missing from the winning break this time, was an
> > > > unlucky George Hincapie (High Road). The tall American said he was
> > > > strong enough to have been with the winners until he ran into trouble.
> > > > He was riding at the front on the Bersée section of cobblestones, 53km
> > > > from the finish, and racing as well as he has ever ridden in the Hell
> > > > of the North, when his rear wheel broke. "I had great legs," Hincapie
> > > > said, "but there was nothing I could do." "http://www.velonews.com/article/74625/boonen-wins-paris-roubaix
>
> > > > Of course this is only anecdotal "evidence" that low spoke count
> > > > carbon wheels isn't the best choice for a race like Paris-Roubaix,
> > > > still the main contender teams; CSC (Cancellera winner: 2006, O'Grady
> > > > 2007) and Quick Step (Boonen 2005, 2008) seems to think so.
>
> > > > --
> > > > Regards
>
> > > I'll say. A normal flat race would make sense to use deep section
> > > wheels, as they are more than strong enough for that, and provide a
> > > useful advantage. But Paris-Roubaix isn't a normal flat race. The
> > > cobbles is where people get dropped, and there, despite insane speed,
> > > it isn't wind resistance on the wheels that separates the men from the
> > > boys. Given the prospect of having a race ruined by a broken wheel, vs
> > > a few watts saved on the non-critical smooth sections, it's obvious to
> > > me what wheels to choose. Big tires too like Ballan.
>
> > > And a 90kg+ guy like Magnus using anything but extra strong wheels
> > > seems foolish.
>
> > > Joseph
>
> > I think it's just a matter of time before one of the wheel
> > manufacturers comes up with a batch of Roubaix special carbon wheels.
> > There's no reason why those deep carbon rims can't be strong enough to
> > handle the cobbles if enough material is added, and in a race where a
>
> I agree. And with all the special one-off bikes that are used, I'm
> surprised the wheel manufacturers haven't already.
>
> > 46 ring is "small" the extra weight won't be an issue. In addition to
> > aerodynamics, tall rims don't get sucked into deep mud as hard as box
> > sections.
>
> Is that why those wheels are used so often in cyclo-cross? I often
> wondered why they are so prevalent.
>
> Joseph

Maybe they already have. We wouldn't know by looking at them. Zipp
already makes heavier versions of some rims specifically for
clydesdales and cyclocross. I believe CSC was using the cyclocross
wheels at Flanders because they also had more spokes than usual.

 

[Hobbes@spnb&s.com]

On Tue, 15 Apr 2008 04:11:46 GMT, Ryan Cousineau <[email protected]> wrote:

>In article
><e58771[email protected]>,
> "joseph.santani[email protected]" <[email protected]> wrote:
>
>> On Apr 14, 6:27 pm, [email protected] wrote:
>> > On Apr 14, 8:35 am, "[email protected]"
>> >
>> >
>> >
>> > <[email protected]> wrote:
>> > > On Apr 14, 1:17 pm, [email protected] wrote:
>
>> > I think it's just a matter of time before one of the wheel
>> > manufacturers comes up with a batch of Roubaix special carbon wheels.
>> > There's no reason why those deep carbon rims can't be strong enough to
>> > handle the cobbles if enough material is added, and in a race where a
>>
>> I agree. And with all the special one-off bikes that are used, I'm
>> surprised the wheel manufacturers haven't already.
>>
>>
>> > 46 ring is "small" the extra weight won't be an issue.  In addition to
>> > aerodynamics, tall rims don't get sucked into deep mud as hard as box
>> > sections.
>>
>> Is that why those wheels are used so often in cyclo-cross? I often
>> wondered why they are so prevalent.
>
>I believe that's the theory, yes. After all, the aero considerations are
>low, and the weight can't be any better than that of the best
>low-profile rims.
>
>Also, and never underestimate this factor, CX bikes with Zipp 404s look
>way cool.

The aero and semi-aero rims shed mud well and are also stiffer and more rugged.
I'm thinking they don't get used in P-R as a concession to rider comfort.

Ron

 

[Tim McNamara]

In article <[email protected]>,
Hobbes@spnb&s.com wrote:

> The aero and semi-aero rims shed mud well and are also stiffer and
> more rugged. I'm thinking they don't get used in P-R as a concession
> to rider comfort.

Oy. Umm, how much more "shock absorption" do you think box section rims
provide compared to an "aero" rim?

 

[Hobbes@spnb&s.com]

On Tue, 15 Apr 2008 14:27:28 -0500, Tim McNamara <[email protected]> wrote:

>In article <[email protected]>,
> Hobbes@spnb&s.com wrote:
>
>> The aero and semi-aero rims shed mud well and are also stiffer and
>> more rugged. I'm thinking they don't get used in P-R as a concession
>> to rider comfort.
>
>Oy. Umm, how much more "shock absorption" do you think box section rims
>provide compared to an "aero" rim?

Don't know. They are certainly much more flexible. Are you presuming that it
couldn't make a difference?

 

[Anthony DeLorenzo]

On Apr 15, 4:23 pm, Hobbes@spnb&s.com wrote:
> >> The aero and semi-aero rims shed mud well and are also stiffer and
> >> more rugged. I'm thinking they don't get used in P-R as a concession
> >> to rider comfort.
>
> >Oy. Umm, how much more "shock absorption" do you think box section rims
> >provide compared to an "aero" rim?
>
> Don't know. They are certainly much more flexible. Are you presuming that it
> couldn't make a difference?

Probably not as much difference as those air-filled rubber shock
absorbers that are wrapped around the rims, aka the tires.

 

[[email protected]]

Anthony DeLorenzo wrote:

>>>> The aero and semi-aero rims shed mud well and are also stiffer
>>>> and more rugged. I'm thinking they don't get used in P-R as a
>>>> concession to rider comfort.

>>> Oy. Umm, how much more "shock absorption" do you think box
>>> section rims provide compared to an "aero" rim?

>> Don't know. They are certainly much more flexible. Are you
>> presuming that it couldn't make a difference?

> Probably not as much difference as those air-filled rubber shock
> absorbers that are wrapped around the rims, aka the tires.

That's not the problem but rather how malleable the rim is so that it
doesn't fracture when a tire bottoms on a road hazard. A thin rim
wall that retains the tire can either bend a little or crack and let
the tire blow out. Therein lies the difference. The aluminum rim can
be repaired using a small crescent wrench to straighten the bead.
There is nothing you can do for Carbon fiber composite.

Jobst Brandt

 

[[email protected]]

On Apr 15, 8:04 pm, [email protected] wrote:
> Anthony DeLorenzo wrote:
> >>>> The aero and semi-aero rims shed mud well and are also stiffer
> >>>> and more rugged. I'm thinking they don't get used in P-R as a
> >>>> concession to rider comfort.
> >>> Oy. Umm, how much more "shock absorption" do you think box
> >>> section rims provide compared to an "aero" rim?
> >> Don't know. They are certainly much more flexible. Are you
> >> presuming that it couldn't make a difference?
> > Probably not as much difference as those air-filled rubber shock
> > absorbers that are wrapped around the rims, aka the tires.
>
> That's not the problem but rather how malleable the rim is so that it
> doesn't fracture when a tire bottoms on a road hazard. A thin rim
> wall that retains the tire can either bend a little or crack and let
> the tire blow out. Therein lies the difference. The aluminum rim can
> be repaired using a small crescent wrench to straighten the bead.
> There is nothing you can do for Carbon fiber composite.
>
> Jobst Brandt

That's an interesting point, but in the racing world broken is
broken. A tire blowout costs you as much time as a cracked rim, and a
bent aluminum rim is not going to be repaired and put back into
service. The issue becomes whether or not there is a magnitude of
impact that would fracture a carbon rim but would only bend an
aluminum one without a tire blowout. Seeing how there are people out
there racing cylclocross on Lightweights, I think bottoming out the
tire is not an instant catastrophe for a carbon rim. It seems like
the ideal wheel would be something like the Flashpoint in a tubular.
Even if rim plasticity isn't an issue, aluminum still brakes better
when wet.

 

[Ryan Cousineau]

In article
<0cb5bc[email protected]>,
[email protected] wrote:

> On Apr 15, 8:04 pm, [email protected] wrote:
> > Anthony DeLorenzo wrote:
> > >>>> The aero and semi-aero rims shed mud well and are also stiffer
> > >>>> and more rugged. I'm thinking they don't get used in P-R as a
> > >>>> concession to rider comfort.
> > >>> Oy. Umm, how much more "shock absorption" do you think box
> > >>> section rims provide compared to an "aero" rim?
> > >> Don't know. They are certainly much more flexible. Are you
> > >> presuming that it couldn't make a difference?
> > > Probably not as much difference as those air-filled rubber shock
> > > absorbers that are wrapped around the rims, aka the tires.
> >
> > That's not the problem but rather how malleable the rim is so that it
> > doesn't fracture when a tire bottoms on a road hazard. A thin rim
> > wall that retains the tire can either bend a little or crack and let
> > the tire blow out. Therein lies the difference. The aluminum rim can
> > be repaired using a small crescent wrench to straighten the bead.
> > There is nothing you can do for Carbon fiber composite.
> >
> > Jobst Brandt
>
> That's an interesting point, but in the racing world broken is
> broken. A tire blowout costs you as much time as a cracked rim, and a
> bent aluminum rim is not going to be repaired and put back into
> service. The issue becomes whether or not there is a magnitude of
> impact that would fracture a carbon rim but would only bend an
> aluminum one without a tire blowout. Seeing how there are people out
> there racing cylclocross on Lightweights, I think bottoming out the
> tire is not an instant catastrophe for a carbon rim. It seems like
> the ideal wheel would be something like the Flashpoint in a tubular.
> Even if rim plasticity isn't an issue, aluminum still brakes better
> when wet.

I think that bottoming out in deep mud is less problematic than on
cobbles. And there are very few cobblestones in most world-class CX
races.

--
Ryan Cousineau [email protected] http://www.wiredcola.com/
"In other newsgroups, they killfile trolls."
"In rec.bicycles.racing, we coach them."

 

[Hobbes@spnb&s.com]

On Tue, 15 Apr 2008 16:55:07 -0700 (PDT), Anthony DeLorenzo
<[email protected]> wrote:

>On Apr 15, 4:23 pm, Hobbes@spnb&s.com wrote:
>> >> The aero and semi-aero rims shed mud well and are also stiffer and
>> >> more rugged. I'm thinking they don't get used in P-R as a concession
>> >> to rider comfort.
>>
>> >Oy. Umm, how much more "shock absorption" do you think box section rims
>> >provide compared to an "aero" rim?
>>
>> Don't know. They are certainly much more flexible. Are you presuming that it
>> couldn't make a difference?
>
>Probably not as much difference as those air-filled rubber shock
>absorbers that are wrapped around the rims, aka the tires.

Not as much ain't the same thing as doesn't.

How much travel is available from the tires? Maximum is going to be about 20mm -
24mm sewup minus radius of the tire bed of the rim - minus thickness of rubber
latex and casing. That's brave low pressure for a race without a pit every half
mile so let's get some safety margin and not wallow around and pump it up hard
enough for only 15mm of compliance. Since so many of the obstacles are
relatively sharp edged you might want even more pressure to make sure. Still, 15
stinking millimeters, maximum and that's with sewups.

So how much does a box section rim on a 32 spoke wheel give when a 170 pound guy
with a bike hits rocks at 25per? That's a harder question. But I'll bet real
cash the answer is not insubstantial compared to the mere 15mm we're allowing
from the tire.

Hey, how do I submit a proposal for a steam-punkish, Fogel-project to measure
this?

 

[[email protected]]

On Apr 16, 11:02 am, Hobbes@spnb&s.com wrote:
> On Tue, 15 Apr 2008 16:55:07 -0700 (PDT), Anthony DeLorenzo
>
> <[email protected]> wrote:
> >On Apr 15, 4:23 pm, Hobbes@spnb&s.com wrote:
> >> >> The aero and semi-aero rims shed mud well and are also stiffer and
> >> >> more rugged. I'm thinking they don't get used in P-R as a concession
> >> >> to rider comfort.
>
> >> >Oy. Umm, how much more "shock absorption" do you think box section rims
> >> >provide compared to an "aero" rim?
>
> >> Don't know. They are certainly much more flexible. Are you presuming that it
> >> couldn't make a difference?
>
> >Probably not as much difference as those air-filled rubber shock
> >absorbers that are wrapped around the rims, aka the tires.
>
> Not as much ain't the same thing as doesn't.
>
> How much travel is available from the tires? Maximum is going to be about 20mm -
> 24mm sewup minus radius of the tire bed of the rim - minus thickness of rubber
> latex and casing. That's brave low pressure for a race without a pit every half
> mile so let's get some safety margin and not wallow around and pump it up hard
> enough for only 15mm of compliance. Since so many of the obstacles are
> relatively sharp edged you might want even more pressure to make sure. Still, 15
> stinking millimeters, maximum and that's with sewups.
>
> So how much does a box section rim on a 32 spoke wheel give when a 170 pound guy
> with a bike hits rocks at 25per? That's a harder question. But I'll bet real
> cash the answer is not insubstantial compared to the mere 15mm we're allowing
> from the tire.
>
> Hey, how do I submit a proposal for a steam-punkish, Fogel-project to measure
> this?


Back of the envelope says that a straight 14ga spoke of 280mm length
and 110kgf tension goes slack at 5mm of rim deflection, so that's the
practical limit of compliance.
Funny you should mention not having a pit every half mile. The
cobbled sectors in Paris Roubaix run up to 3.7km, are narrow, and are
closed to team cars. I think that overriding any theoretical
assessment of comfort is the realization that every piece of equipment
that rolls up to that start line is going to get crashed at least
once. Crash survival probably gets much more consideration than
comfort for a lot of parts.

 

[[email protected]]

On Wed, 16 Apr 2008 11:02:56 -0400, Hobbes@spnb&s.com wrote:

>On Tue, 15 Apr 2008 16:55:07 -0700 (PDT), Anthony DeLorenzo
><[email protected]> wrote:
>
>>On Apr 15, 4:23 pm, Hobbes@spnb&s.com wrote:
>>> >> The aero and semi-aero rims shed mud well and are also stiffer and
>>> >> more rugged. I'm thinking they don't get used in P-R as a concession
>>> >> to rider comfort.
>>>
>>> >Oy. Umm, how much more "shock absorption" do you think box section rims
>>> >provide compared to an "aero" rim?
>>>
>>> Don't know. They are certainly much more flexible. Are you presuming that it
>>> couldn't make a difference?
>>
>>Probably not as much difference as those air-filled rubber shock
>>absorbers that are wrapped around the rims, aka the tires.
>
>Not as much ain't the same thing as doesn't.
>
>How much travel is available from the tires? Maximum is going to be about 20mm -
>24mm sewup minus radius of the tire bed of the rim - minus thickness of rubber
>latex and casing. That's brave low pressure for a race without a pit every half
>mile so let's get some safety margin and not wallow around and pump it up hard
>enough for only 15mm of compliance. Since so many of the obstacles are
>relatively sharp edged you might want even more pressure to make sure. Still, 15
>stinking millimeters, maximum and that's with sewups.
>
>So how much does a box section rim on a 32 spoke wheel give when a 170 pound guy
>with a bike hits rocks at 25per? That's a harder question. But I'll bet real
>cash the answer is not insubstantial compared to the mere 15mm we're allowing
>from the tire.
>
>Hey, how do I submit a proposal for a steam-punkish, Fogel-project to measure
>this?

Dear Hobbes,

Just rolling under the hub on smooth pavement, a rim deflects only a
thousandth of an inch or so.

That's obviously imperceptible.

But some riders occasionally notice spokes rattling when they hit
things hard. The rattling means that the rim deflected enough to lose
all its tension. That's around 3 to 5 mm, depending on initial
tension, spoke length, and spoke gauge.

That's getting close to snake-bite territory, where the tire is mashed
flat against the rim. (For an impact flat, a tire already mashed flat
against the rim must be given a good whack to split the rubber tube
pinched between the rim and the road.)

So what you're really wondering is how much impact is needed to mash a
rim to spoke-rattle depth for deep carbon versus metal box rim.

If the deep carbon rim flattened only half as much as the metal box
rim, the suspension travel difference would be only half of 3 to 5 mm.

Maybe someone can calculate the theoretical difference for a deep
carbon versus a metal box rim, but I suspect that difference will
remain more theoretical than noticeable to a rider.

Cheers,

Carl Fogel

 

[[email protected]]

Carl Fogel wrote:

>>>>>> The aero and semi-aero rims shed mud well and are also stiffer
>>>>>> and more rugged. I'm thinking they don't get used in P-R as a
>>>>>> concession to rider comfort.

>>>>> Oy. Umm, how much more "shock absorption" do you think box
>>>>> section rims provide compared to an "aero" rim?

>>>> Don't know. They are certainly much more flexible. Are you
>>>> presuming that it couldn't make a difference?

>>> Probably not as much difference as those air-filled rubber shock
>>> absorbers that are wrapped around the rims, aka the tires.

>> Not as much ain't the same thing as doesn't.

>> How much travel is available from the tires? Maximum is going to
>> be about 20mm - 24mm sewup minus radius of the tire bed of the rim
>> - minus thickness of rubber latex and casing. That's brave low
>> pressure for a race without a pit every half mile so let's get some
>> safety margin and not wallow around and pump it up hard enough for
>> only 15mm of compliance. Since so many of the obstacles are
>> relatively sharp edged you might want even more pressure to make
>> sure. Still, 15 stinking millimeters, maximum and that's with
>> sewups. So how much does a box section rim on a 32 spoke wheel
>> give when a 170 pound guy with a bike hits rocks at 25per? That's
>> a harder question. But I'll bet real cash the answer is not
>> insubstantial compared to the mere 15mm we're allowing from the
>> tire. Hey, how do I submit a proposal for a steam-punkish,
>> Fogel-project to measure this?

> Just rolling under the hub on smooth pavement, a rim deflects only a
> thousandth of an inch or so.

> That's obviously imperceptible.

> But some riders occasionally notice spokes rattling when they hit
> things hard. The rattling means that the rim deflected enough to
> lose all its tension. That's around 3 to 5 mm, depending on initial
> tension, spoke length, and spoke gauge.

Unless the wheel is under tensioned, spokes do not rattle. Spokes
that become slack under shock load, if they make any sound, make a
sharp non-reverberating twang. This is especially so for interleaved
and properly tensioned wheels.

> That's getting close to snake-bite territory, where the tire is
> mashed flat against the rim. (For an impact flat, a tire already
> mashed flat against the rim must be given a good whack to split the
> rubber tube pinched between the rim and the road.)

Snake bites occur from short length obstacles in contrast to spoke
slackening that occurs typically from road washboard, for instance.
In that event the contact length is sufficient to prevent bottoming
the tire while slackening spokes.

> So what you're really wondering is how much impact is needed to mash
> a rim to spoke-rattle depth for deep carbon versus metal box rim.

That requires striking a rock or root less than 100mm length in the
direction of travel.

> If the deep carbon rim flattened only half as much as the metal box
> rim, the suspension travel difference would be only half of 3 to 5
> mm.

That is not the issue. Damaging the bead is a fracture with
composites and a mild ding for aluminum. The first one releases the
tire the other usually doesn't. I have repaired enough metal rims
while having seen failed composite rims at the LBS.

> Maybe someone can calculate the theoretical difference for a deep
> carbon versus a metal box rim, but I suspect that difference will
> remain more theoretical than noticeable to a rider.

Leave it to theory!

Jobst Brandt