"brevettata" tandem?

On Mar 7, 8:27 pm, Ryan Cousineau wrote:
In article . com,
"Scott Gordo" wrote:





On Mar 7, 2:07 am, Ryan Cousineau wrote:
In article ,
A Muzi wrote:

Ryan Cousineau wrote:
I'm trying to chase down the provenance of a bike I haven't seen yet.
At a guess, I google-translated the name, and (as many of you know)
it
means "patented" in the land of Giros and Fiats.
Any ideas what make of tandem would likely be misidentified this way?
Or
is it a real marque?
I hope to take a look at it fairly shortly.

A Muzi wrote:
Can't help with your specific problem but it happens all the time.
He has no idea what it is. He looked at a part marked -
Brevettata= Patented, Italy
I'm going to see the bike tonight (the price is in my range, and I
just want a "around the park" tandem for me and the missus). I don't
want a bike that will fall apart in a mile, but looks are probably
more important than how many gears it has.

Any general remarks on tandems of this type? Is there likely to be
some freaky Italy-specific issues I might not expect versus, say, an
English or American tandem of the same era?

Send photos to me or some other doddering old bikie for a general
assessment. Or, better, post some photos for RBT review! There aren't
simple guidelines but we can help you avoid known or obvious troubles.

Well, you can't help me avoid trouble now that I've bought the bike!

It turns out it was...a 20"-wheeled folding(ish) tandem!

http://flickr.com/photos/rcousine/41...n/photostream/

I've had a couple of those gimmicks in the non-tandem version. One
said that it was made by Bianchi, and made in Italy. I've had another
one with identical construction that bore some Frenchy name I can't
recall.

All I can say is that what they had in style they lacked in any sort
of torsional rigidity. They're commically flexy, from the handlebars
on down, so doubling up on one, ESPECIALLY as a single speed...if you
see anything that looks like a hill, head in the other direction.

Didn't notice it was a 3sp. That will definitely help.


Keep an eye on them quick releases, especially the one that holds the
stem in place. The ones on my bikes were an insult to Tullio.

The good news is there are _no_ quick releases on this bike. The places
where you would expect them, there are these inch-tall, heavily-built
collars held together with 8mm hex bolts.

Even the frame hinge is held together that way.

I was planning on doing the same thing, but I wound up just selling
them instead. I'm pretty sure that I've read here that a good QR can
provide more clamping force than regular nuts and bolts, but, like I
said, these were some pretty poor QRs.

If you look upthread, this frame has a lot of the tropes of Andrew's
pink Bianchi, most notably the bulged head and seat tubes.

Mine bikes had the same. That swanky loop that forms the rear triangle/
rack was my favorite aspect of the bike.

With all that said, it'll be a funny little ride and will def raise
some smiles.

Undoubtedly. It's wife-approved!

Riding our old Schwinn tandem is the most dumb-fun my GF and I have.
It's like an instant parade -- strangers lining the streets smile and
wave. We should hand out balloons. I just hope that you guys are
lighter than we are.

ps: Oh yeah, I don't believe that ANY of those parts followed any kind
of standard, so don't leave it out in the snow

Andrew: wanna sell your Bianchi?

--
Ryan Cousineau /
"I don't want kids who are thinking about going into mathematics
to think that they have to take drugs to succeed." -Paul Erdos- Hide quoted text -

- Show quoted text -

/s

On 2007-03-08, wrote:
[...]
I'd wondered about the ratios that you and other posters have
mentioned, but I'm still wondering about the skidding and whether it's
a small front tire on clean, dry pavement.
I can see that the drum's leverage improves with a smaller wheel, but
it seems as if the rim caliper would still have an advantage.

Ben C wrote:
-snip-
It may be that drum brakes aren't specifically designed for a size of
wheel, so when you put a drum brake all geared up for a large wheel on a
small-wheeled bike the brakes are sharper than you expect, so it becomes
easier to lock the wheel and skid inadvertently.

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

In article m,
"Scott Gordo" wrote:

On Mar 7, 8:27 pm, Ryan Cousineau wrote:
In article . com,
"Scott Gordo" wrote:

On Mar 7, 2:07 am, Ryan Cousineau wrote:
In article ,
A Muzi wrote:

Ryan Cousineau wrote:

Well, you can't help me avoid trouble now that I've bought the bike!

It turns out it was...a 20"-wheeled folding(ish) tandem!

http://flickr.com/photos/rcousine/41...n/photostream/

With all that said, it'll be a funny little ride and will def raise
some smiles.

Undoubtedly. It's wife-approved!

Riding our old Schwinn tandem is the most dumb-fun my GF and I have.
It's like an instant parade -- strangers lining the streets smile and
wave. We should hand out balloons. I just hope that you guys are
lighter than we are.

Heh. At our fattest, the two of us don't break 300 pounds together.
Actual riding weights should be substantially less than that.

--
Ryan Cousineau 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

On Fri, 09 Mar 2007 04:19:17 GMT, Ryan Cousineau
wrote:

[snip]

Heh. At our fattest, the two of us don't break 300 pounds together.
Actual riding weights should be substantially less than that.

Dear Ryan,

You meant to write, "At my fattest, the two of us don't break 300
pounds together."

Pointedly,

Mrs. R. Cousineau

On Mar 8, 6:21 am, Mark Hickey wrote:
wrote:

In any case, I don't see yet how a smaller front wheel would allow
skidding on clean, dry pavement when a larger front wheel won't skid.
Maybe there's some geometry change? Or maybe I've misunderstood which
wheel?

Consider that, on the 20" wheel'd bike, the brake surfaces are moving
past each other 35% faster, thereby producing 35% more friction at a
given brake lever force. I think that explains it (though much
simplified, and I'm sure minus a number of fascinating details that a
brake expert would add).

It would be better to think in terms of torque
and force, because braking is a force, not
dependent on shoe velocity; you get roughly the
same braking force when applying the lever at
20 mph and 10 mph.

Suppose the brake shoes are at 50 mm radius from
the axle and apply a force Fbrake when the lever is
squeezed. This exerts a torque = Fbrake*50 on the wheel.
The actual decelerating force is the force at the
tire radius Rtire, Fdecel = torque/Rtire.
Rtire is maybe 335mm for a 700c wheel and 250mm
for a 20" wheel, so the same drum brake on the
small wheeled bike is about 1.3x more effective.

Ben

In article ,
wrote:

On Fri, 09 Mar 2007 04:19:17 GMT, Ryan Cousineau
wrote:

[snip]

Heh. At our fattest, the two of us don't break 300 pounds together.
Actual riding weights should be substantially less than that.

Dear Ryan,

You meant to write, "At my fattest, the two of us don't break 300
pounds together."

Pointedly,

Mrs. R. Cousineau

Duly noted.

But actually, on those occasions when I blog about the missus, she is
inevitably described as "The Lovely One," which is a tidily
pseudononymous phrase.

--
Ryan Cousineau 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

On 2007-03-09, wrote:
On Mar 8, 6:21 am, Mark Hickey wrote:
wrote:

In any case, I don't see yet how a smaller front wheel would allow
skidding on clean, dry pavement when a larger front wheel won't skid.
Maybe there's some geometry change? Or maybe I've misunderstood which
wheel?

Consider that, on the 20" wheel'd bike, the brake surfaces are moving
past each other 35% faster, thereby producing 35% more friction at a
given brake lever force. I think that explains it (though much
simplified, and I'm sure minus a number of fascinating details that a
brake expert would add).

It would be better to think in terms of torque
and force, because braking is a force, not
dependent on shoe velocity; you get roughly the
same braking force when applying the lever at
20 mph and 10 mph.

Braking is also a power-- the rate at which kinetic energy of the bike
is converted into heat.

To decelerate two bikes (of the same mass etc., but one of which has
smaller wheels) at the same rate must take the same power.

Power is force * speed where speed is the relative speed of drum and
shoe.

The larger wheeled bike has more force at the drum, but less speed
there, so power works out the same.

But for sudden brake locking experiments, rather than prolonged braking,
force rather than power is more likely to be relevant, and so it's the
higher force at the tyre for given braking effort that we reckon makes
it easier to lock the wheel if it's small.

Ben C wrote:

Braking is also a power-- the rate at which kinetic energy of the bike
is converted into heat.

To decelerate two bikes (of the same mass etc., but one of which has
smaller wheels) at the same rate must take the same power.

Power is force * speed where speed is the relative speed of drum and
shoe.

The larger wheeled bike has more force at the drum, but less speed
there, so power works out the same.

Good point, but I doubt that the efficiency of the brake in converting
the kinetic energy to heat is linear with respect to velocity.

--

David L. Johnson

"Business!" cried the Ghost. "Mankind was my business. The common
welfare was my business; charity, mercy, forbearance, and
benevolence, were, all, my business. The dealings of my trade were but
a drop of water in the comprehensive ocean of my business!" --Dickens,

On Thu, 08 Mar 2007 06:21:35 -0700, Mark Hickey
wrote:

[snip]

Meanwhile, this is as good a spot as any to announce that I saw what
may be the first turkey vultures of spring, circling in the late
afternoon sun and being harried by what turned out to be a pair of
crows.

Niiiice. I was recently visiting my son and his family in East Texas,
and was out for a morning ride on my daughter-in-law's MTB through a
local preserve by a lake. As I came around a bend in the trail, a
pair of bald eagles swooped out of a tree, down the trail in front of
me. What amazed me most was the SIZE of the larger of the two, and
the noise generated by their (huge) wings. Sadly, no camera (and even
if I had one, I'm sure I would have still missed the shot due to an
overdose of awe).

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $795 ti frame

Dear Mark,

Yesterday, the turkey vulture decided to roost on the sunny side of
the blue spruce, making it possible for an incompetent photographer to
capture its red head and white beak:

http://i15.tinypic.com/42n3dpx.jpg

Notice that the bird is obviously peering down at me.

It's rather annoying to sneak around in a stealthy fashion, trying to
avoid disturbing animals, only to find that they're using their
superior eyesight to watch you every step of the way.

Not long ago, I was walking along the tops of the bluffs above the
Arkansas River with my camera turned on and my orange watch cap
stuffed into a pocket to avoid detection, looking down at the river
bottom for a fox.

No fox was visible.

There was an odd bush, however, in a clearing near a small grove of
saplings where I think the fox has a den. I stared at it for a while,
thinking that it might be a fox, but that was just wishful thinking.
What the hell, I took a picture, just so I could see the details
later.

Here's the full-size picture. It's fuzzy, but the odd bush is pretty
much dead-center if you draw diagonals from the corners:

http://i15.tinypic.com/29zsbux.jpg

Here's a cropped view of the bush, in the middle about 20% up from the
bottom:

http://i17.tinypic.com/2mez32u.jpg

You can see why I didn't waste more time on that indistinct bush.

A little further along the top of the bluff, I happened to look down
again.

The bush, which had been sitting still and watching me, was now
walking to my right, toward its den, showing its pale, bottle-brush
tail.

Large picture, left-click in lower right in Explorer for full-size,
bush again dead center:

http://i17.tinypic.com/33lds09.jpg

Cropped view of bush walking to the right:

http://i15.tinypic.com/2ik9y09.jpg

Then the bush turned its head to stare at me. You can see the black
tips of its ears:

Large view, again dead center:

http://i15.tinypic.com/2q9jja0.jpg

Cropped view of bush's black ear-tips:

http://i16.tinypic.com/2wmnihy.jpg

Like the turkey vulture, the bush had been watching me all the time,
easily spotting me 250 yards away.

Cheers,

Carl Fogel

On Mar 7, 1:57 pm, A Muzi wrote:
-snip-



Ryan Cousineau wrote:
Well, you can't help me avoid trouble now that I've bought the bike!
It turns out it was...a 20"-wheeled folding(ish) tandem!
http://flickr.com/photos/rcousine/41...n/photostream/
Note graceful curved, integral rack/rear end.
http://flickr.com/photos/rcousine/41...n/photostream/
Here's the head badge ("G") and frame sticker.
http://flickr.com/photos/rcousine/41...n/photostream/
http://flickr.com/photos/rcousine/41...n/photostream/
Sorry about the taken-in-haste (repent at leisure) photos.
There's another badge that is all but obliterated, except for some faint
traces of the Italian tricolour. The notorious "BREVETTATA" badges were
just under the seatpost clamps on both seat tubes.
Cottered cranks, Aprilia (!) lighting system driven by a sidewall
generator,Carnielli(?) saddles. The strange hanging dropouts seem to
have a "C" cut into them (the second photo shows the mirror-image one on
the left side)
The frame has a proper split-shell eccentric front BB, and all the
frame's folding points (seatposts, hinge, bars, stem) have 8mm hex bolts
in them.
The brakes are Sturmey-Archer drums front and rear. The rear is an AB
(cable-operated drum) 3-speed hub stamped "70", which should be the
production year. Hub seems in good order, but only one gear is available
right now. That's the first order of business.
The shifter is mounted on the stoker's seatpost.
The "keel tube" is a pair of parallel bolted-in tubes about the same
diameter as the rear rack/triangle/whatever tubing. The rear "triangle"
also appears unboltable, though you'd have to be trying to fit this
sucker in a Cinquecento to want to do so, I suspect.
It's shopworn, but obviously lightly used. It looks cute and amusingly
retro. It should hold up well for around the park. The frame appears to
be braced in all the likely failure points, and construction is by
indifferent-looking welds.
C$220 took the whole thing away.
So, what is it?

Most probably made byCarnielli (they made Bottecchia &Graziella
besides Carniellilabel exercise/child/specialty bikes). These 20-inch
frame system components were sold to many European manufacturers. You
can see the similarity to my Bianchi. Gitane, Cazenave, etc, etc were
built from the same parts with minor detail changes.

http://www.yellowjersey.org/aq.html
--
Andrew Muziwww.yellowjersey.org
Open every day since 1 April, 1971

Coming back to this post rather late, I should say that a kindly
Briton named James dug up some fascinating new information, including
photos of another one of thses tandems!

http://www.bikecult.com/works/collec...razzitand.html

The bike in question has some interesting detail changes from mine
(notably, the single-sided drivetrain), but the frame is clearly
identical, with all of the tandem-specific bracing in the right shapes
and places.

Most notably to me, this explains why my "Carnielli" would have a big
serif "G" logo on the head tube: it's a Graziella. The font on this
bike's logo is unmistakably the same as the font on my bike's head
tube badge. Well, sticker.

There's also one more detail, which I will describe in 8 hours and 36
minutes.