New Cervelo Model

What about braking force? I guess that works out to a tension on the
stays?

In article <[email hidden]>, Mike

Reed said:

What about braking force? I guess that works out to a tension on the
stays?

If the seatstays are truly superfluous, why doesn't Cervelo mount the
rear brake on the seattube and rid itself of the vestiges?

Luke

In article <[email hidden]>,

Luke said:

In article <[email hidden]>, Mike

Reed said:

What about braking force? I guess that works out to a tension on the
stays?

If the seatstays are truly superfluous, why doesn't Cervelo mount the
rear brake on the seattube and rid itself of the vestiges?

Luke

That is a question best directed to the UCI. In short: the rules require
a diamond-frame bicycle (with a bunch of dimensional restrictions that
are too boring to explain). The seat stays are required for that reason.

--
Ryan Cousineau [email hidden] http://www.wiredcola.com/
"I don't want kids who are thinking about going into mathematics
to think that they have to take drugs to succeed." -Paul Erdos

Quoted message said:

This is the new Cervelo model :

http://www.cyclingnews.com/photos/2006/feb06/hetvolk06/index.php?id=live/DSC02027

from what I've heard the seatstays contribute very little to the
structure. the chainstays and seatube are strong enough that the bike
would be ridable without seatstays.

-Amit

I had a conversation w/ a local yet prominent framebuilder in CO,
regarding the use of carbon stays on otherwise non-carbon bikes. He
said that the reason no one expressed concerns over the potential for
bad glue jobs is that there's almost no stress on the seatstays and
therefore the junction doesn't have to be that strong.

It should follow that w/ sufficiently strong chainstays, the seatstays
are even less necessary if not completely superfluous.

Scott said:

Quoted message said:

This is the new Cervelo model :

http://www.cyclingnews.com/photos/2006/feb06/hetvolk06/index.php?id=live/DSC02027

from what I've heard the seatstays contribute very little to the
structure. the chainstays and seatube are strong enough that the bike
would be ridable without seatstays.

-Amit

I had a conversation w/ a local yet prominent framebuilder in CO,
regarding the use of carbon stays on otherwise non-carbon bikes. He
said that the reason no one expressed concerns over the potential for
bad glue jobs is that there's almost no stress on the seatstays and
therefore the junction doesn't have to be that strong.

It should follow that w/ sufficiently strong chainstays, the seatstays
are even less necessary if not completely superfluous.

From which it follows that carbon seatstays are essentially a gimmick, anyway.

Dan

Dan Connelly said:

Scott said:

Quoted message said:

This is the new Cervelo model :

http://www.cyclingnews.com/photos/2006/feb06/hetvolk06/index.php?id=live/DSC02027

from what I've heard the seatstays contribute very little to the
structure. the chainstays and seatube are strong enough that the bike
would be ridable without seatstays.

-Amit

I had a conversation w/ a local yet prominent framebuilder in CO,
regarding the use of carbon stays on otherwise non-carbon bikes. He
said that the reason no one expressed concerns over the potential for
bad glue jobs is that there's almost no stress on the seatstays and
therefore the junction doesn't have to be that strong.

It should follow that w/ sufficiently strong chainstays, the seatstays
are even less necessary if not completely superfluous.

From which it follows that carbon seatstays are essentially a gimmick, anyway.

Dan

You're right. He admitted that, too. Went on to joke about how it was
such a huge profit maker for him, as it made it easier and less
expensive to build the frame and yet he could sell it for more.

[email hidden] wrote:

I did see this bike (the R3) in person this weekend and the cervelo
employee said the same thing i had heard, the frame without the
seatstays is very strong and stiff.

if you follow this link you can see a test of the bayonne (the yet to
be released lightweight version of the R3) , and the wispy seatstays
are mentioned :

http://www.cervelo.com/bikes.aspx?bike=Bayonne2006

Quoted message said:

Googling "chainstay bridge" in this group brings up a number of
opinions. I was never convinced by any of the arguments in favor
of the chainstay bridge as a significant structural element.

if you follow this link

http://www.cervelo.com/section.aspx?m=Engineering

you can check out the "8 grams of engineering article", and it explains
the design of the soloist chainstay bridge. i know that the early
soloists had no bridge and last year's model had one. if this article
is to be believed, the implementation of a chainstay bridge isn't so
simple and the bridge had to be carefully designed.

Quoted message said:

if you follow this link

http://www.cervelo.com/section.aspx?m=Engineering

you can check out the "8 grams of engineering article", and it explains
the design of the soloist chainstay bridge. i know that the early
soloists had no bridge and last year's model had one. if this article
is to be believed, the implementation of a chainstay bridge isn't so
simple and the bridge had to be carefully designed.

That's an interesting article. Thanks. It's rare to see a
bike company actually talk about that kind of technical detail.
It seems that some of the failed designs failed to improve
fatigue life because they put welds in vulnerable places or
because adding metal redistributed the stress to vulnerable
places, or both. More metal isn't necessarily better.

The EFBe test uses high loads to fail a bike before
100,000 cycles, because real bikes last more pedaling
cycles than that. This has been debated before in rbt,
but presumably a chainstay bridge that is worse on the
EFBe test is worse in the real world too.

The actual bridge they used is pretty big compared to the
chainstays so it has a real effect on the stiffness of the
assembly. In classical steel construction the bridge is
a pretty wimpy tube so I think it's fairly cosmetic.

As proof that I shuld be riding instead (hey, it's dark out)
here are some pictures of chainstay bridge areas
on frames, and three different approaches:

http://www.ucolick.org/~bjw/misc/rbt/cstays.html

I didn't have access to any stay-free bikes, but they do exist.

Quoted message said:

That's an interesting article. Thanks. It's rare to see a
bike company actually talk about that kind of technical detail.
It seems that some of the failed designs failed to improve
fatigue life because they put welds in vulnerable places or
because adding metal redistributed the stress to vulnerable
places, or both. More metal isn't necessarily better.

yes, and the article mentions they had failures at the bridge in their
prototype soloists so that's why (i suppose) it was left out on the
first production models.

Quoted message said:

The actual bridge they used is pretty big compared to the
chainstays so it has a real effect on the stiffness of the
assembly. In classical steel construction the bridge is
a pretty wimpy tube so I think it's fairly cosmetic.

the effect isn't measured in (just) stiffness but also in fatigue
resistance, at least with respect to the EFBe test.

Quoted message said:

As proof that I shuld be riding instead (hey, it's dark out)
here are some pictures of chainstay bridge areas
on frames, and three different approaches:

http://www.ucolick.org/~bjw/misc/rbt/cstays.html

yes, but a bridge arrangment that looks good might actually be bad, as
that article shows and the combination of the bridge and gusset was the
worst.

Quoted message said:

I didn't have access to any stay-free bikes, but they do exist.

if you mean chainstay bridge-free, cannondale is a common example.