Cantilevered rear aluminum dropouts

I recently purchased an aluminum-framed bicycle at a yard sale. I am
curious as to the why the rear dropout is designed the way it is. It
is cantilevered more than I see on other bikes and this seems strange
to me. Other bicycles have the wheel axle closer to the junction of
the seat and chain stays. This design seems unnecessary and I worry
about cracking of an aluminum frame.

Pictures are at http://www.lobuglio.org/redbike/

The bike has no identifying information on it (no head-badge or
decals). It was a charity yard sale so the owner wasn't there when I
bought it. It has Shimano 105 components with a 7 speed cassette
(13-28) and a double chainring up front (52-42) in the back. The rear
spacing is 126 mm, so I am guessing this is late 1980's. On the bottom-
right chainstay it has "B1-0302" stamped (as if by a dot-matrix
printer) and on the left chainstay is the serial number (11 numbers,
the first five of which are 65804). I am curious as to the why the
rear dropout is designed the way it is (cantilevered) and if anyone
might have any guesses as to its origin.

Thanks

Joe LoBuglio

On Feb 1, 8:37 am, "Joe LoBuglio" wrote:
I recently purchased an aluminum-framed bicycle at a yard sale. I am
curious as to the why the rear dropout is designed the way it is. It
is cantilevered more than I see on other bikes and this seems strange
to me. Other bicycles have the wheel axle closer to the junction of
the seat and chain stays. This design seems unnecessary and I worry
about cracking of an aluminum frame.

Pictures are athttp://www.lobuglio.org/redbike/

The bike has no identifying information on it (no head-badge or
decals). It was a charity yard sale so the owner wasn't there when I
bought it. It has Shimano 105 components with a 7 speed cassette
(13-28) and a double chainring up front (52-42) in the back. The rear
spacing is 126 mm, so I am guessing this is late 1980's. On the bottom-
right chainstay it has "B1-0302" stamped (as if by a dot-matrix
printer) and on the left chainstay is the serial number (11 numbers,
the first five of which are 65804). I am curious as to the why the
rear dropout is designed the way it is (cantilevered) and if anyone
might have any guesses as to its origin.

Thanks

Joe LoBuglio

I'd guess it's a Cannondale. They made them that way for looks, small
rear triangles were the fast look back then (and it's red!! wooo
hoo!). I've got a mid-eighties Cannondale m700 and I don't worry about
the cantilevered dropouts cracking, those bikes were over engineered.
I'm sure someone else can help you with the serial numbers. Year and
model are encoded in there somehow.

Cam

Joe LoBuglio wrote:
I recently purchased an aluminum-framed bicycle at a yard sale. I am
curious as to the why the rear dropout is designed the way it is. It
is cantilevered more than I see on other bikes and this seems strange
to me.
It's a Crack n Fail, aka Cannondale from 94 vintage or thereabouts. The
prefered failure mode is through the flattened bottom of the seatstays
but as this frame has survived till now it might live a bit longer

--
---
Marten Gerritsen

INFOapestaartjeM-GINEERINGpuntNL
www.m-gineering.nl

On Thu, 01 Feb 2007 06:18:08 -0800, Cam wrote:

On Feb 1, 8:37 am, "Joe LoBuglio" wrote:
I recently purchased an aluminum-framed bicycle at a yard sale. I am
curious as to the why the rear dropout is designed the way it is. It
is cantilevered more than I see on other bikes and this seems strange
to me. Other bicycles have the wheel axle closer to the junction of
the seat and chain stays. This design seems unnecessary and I worry
about cracking of an aluminum frame.

Pictures are athttp://www.lobuglio.org/redbike/

The bike has no identifying information on it (no head-badge or
decals). It was a charity yard sale so the owner wasn't there when I
bought it. It has Shimano 105 components with a 7 speed cassette
(13-28) and a double chainring up front (52-42) in the back. The rear
spacing is 126 mm, so I am guessing this is late 1980's. On the bottom-
right chainstay it has "B1-0302" stamped (as if by a dot-matrix
printer) and on the left chainstay is the serial number (11 numbers,
the first five of which are 65804). I am curious as to the why the
rear dropout is designed the way it is (cantilevered) and if anyone
might have any guesses as to its origin.

Thanks

Joe LoBuglio

I'd guess it's a Cannondale. They made them that way for looks, small
rear triangles were the fast look back then (and it's red!! wooo
hoo!). I've got a mid-eighties Cannondale m700 and I don't worry about
the cantilevered dropouts cracking, those bikes were over engineered.
I'm sure someone else can help you with the serial numbers. Year and
model are encoded in there somehow.

Cam

I think those frames do have a reputation for failing. See, for instance,
this rbt thread:

http://tinyurl.com/2l6h7r

I think Cannondale marketed this as a weight-saving feature. That's how
they got their "2.8" series of frames down to 2.8 pounds.

I'm curious if anyone thinks there's a problem with riding it until it
fails (if it does fail). I had a chainstay break on one of my bikes and it
didn't make me lose control.

On Feb 1, 9:24 am, M-gineering wrote:
Joe LoBuglio wrote:
I recently purchased an aluminum-framed bicycle at a yard sale. I am
snip
It's a Crack n Fail, aka Cannondale from 94 vintage or thereabouts. The
prefered failure mode is through the flattened bottom of the seatstays
but as this frame has survived till now it might live a bit longer

Thanks, the hints of 2.8 and the Cannondale let me find out more about
this frame.

As it turns out, it is a 3.0 since the cable is routed above the top
tube; the 2.8 had it below the top tube and had more shape to the top
tube (from what I read). It was manufactured in 1991. Since it has the
flattened seat stays where it is welded to the chain stay, I assume it
has the same cracking potential.

Joe

Wasn't this poor design the result of the Klein lawsuit? An attempt
to get around the patent issued to Klein that probably shouldn't have
been granted. The one that claimed the ideal bike frame was aluminum
tubes of certain diameters.

On the fun side, when it fails, the rear wheel will likely just jam in
the frame and you will come skiding to an abrupt stop. No endos thank
you.

Rick

wrote:
Wasn't this poor design the result of the Klein lawsuit? An attempt
to get around the patent issued to Klein that probably shouldn't have
been granted. The one that claimed the ideal bike frame was aluminum
tubes of certain diameters.

On the fun side, when it fails, the rear wheel will likely just jam in
the frame and you will come skiding to an abrupt stop. No endos thank
you.

The biggest danger is that the frame might go squirrely in a fast corner
with unexpected results . I'd check the chainstays thouroughly during
cleaning and stop worrying
--
---
Marten Gerritsen

INFOapestaartjeM-GINEERINGpuntNL
www.m-gineering.nl

On Feb 1, 12:22 pm, "
wrote:
Wasn't this poor design the result of the Klein lawsuit? An attempt
to get around the patent issued to Klein that probably shouldn't have
been granted. The one that claimed the ideal bike frame was aluminum
tubes of certain diameters.

On the fun side, when it fails, the rear wheel will likely just jam in
the frame and you will come skiding to an abrupt stop. No endos thank
you.

Rick


The reason this was done (I assume) was so that the fat stays could
clear the cassette/chain. I don't think the design is as poor as it
may appear because I don't recall many of failing, but others seem to
disagree.

wrote:

The reason this was done (I assume) was so that the fat stays could
clear the cassette/chain. I don't think the design is as poor as it
may appear because I don't recall many of failing, but others seem to
disagree.


clearance is poor, the stays needed a severe crimp (on both sides for
symmetry ) to clear the chain in top gear, they cracked
--
---
Marten Gerritsen

INFOapestaartjeM-GINEERINGpuntNL
www.m-gineering.nl

Joe LoBuglio wrote:
I recently purchased an aluminum-framed bicycle at a yard sale. I am
curious as to the why the rear dropout is designed the way it is. It
is cantilevered more than I see on other bikes and this seems strange
to me. Other bicycles have the wheel axle closer to the junction of
the seat and chain stays. This design seems unnecessary and I worry
about cracking of an aluminum frame.

Pictures are at http://www.lobuglio.org/redbike/

The bike has no identifying information on it (no head-badge or
decals). It was a charity yard sale so the owner wasn't there when I
bought it. It has Shimano 105 components with a 7 speed cassette
(13-28) and a double chainring up front (52-42) in the back. The rear
spacing is 126 mm, so I am guessing this is late 1980's. On the bottom-
right chainstay it has "B1-0302" stamped (as if by a dot-matrix
printer) and on the left chainstay is the serial number (11 numbers,
the first five of which are 65804). I am curious as to the why the
rear dropout is designed the way it is (cantilevered) and if anyone
might have any guesses as to its origin.

What: Early Cannondale
Why: Beats me, just that way.

--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971