Wisdom teeth?

Ignore the fork-hung crank in the no-down-tube frame:

http://www.auctionflex.com/showlot.a...ction=&lang=En
or http://tinyurl.com/66s4gy

Page down to the bottom and see weird half-inch teeth engaging the
inch-pitch chain on the rear.

The front sprocket has normal inch-pitch teeth, so I wonder what the
explanation was?

Cheers,

Carl Fogel

Carl Fogel wrote:

Ignore the fork-hung crank in the no-down-tube frame:

http://tinyurl.com/66s4gy

Page down to the bottom and see weird half-inch teeth engaging the
inch-pitch chain on the rear.

The front sprocket has normal inch-pitch teeth, so I wonder what the
explanation was?

I scrolled around in there and could not find the name (manufacturer)
of the bicycle. Do you know what it is other than circa 1889?

All I could find is:
----------------------------------------------------------------------
Lot: 40

1 19th c. hard tire safety 19th c. hard tire safety having fork hung
crank, retains orig. brakes, 30" wheels, new wooden grips, lamp
bracket, rear drop step, re-covered saddle, older restoration, pin
striped, replaced tire rubber. C. 1889, VG cond.

Estimate: 3,500.00 - 4,500.00
----------------------------------------------------------------------



Jobst Brandt

On Nov 1, 8:43*pm, wrote:
Ignore the fork-hung crank in the no-down-tube frame:

http://www.auctionflex.com/showlot.a...4596&weventite....
orhttp://tinyurl.com/66s4gy

Page down to the bottom and see weird half-inch teeth engaging the
inch-pitch chain on the rear.

The front sprocket has normal inch-pitch teeth, so I wonder what the
explanation was?


I've never seen a good reason for the 'skip tooth' inch-pitch chain
and sprockets in the first place, Carl. Perhaps you have a link to
one.

The outboard bearings on the bb are interesting. A combination of
spindly-looking and functional seeming, assuming they'd protect them
somehow.

On 02 Nov 2008 02:03:49 GMT, wrote:

Carl Fogel wrote:

Ignore the fork-hung crank in the no-down-tube frame:

http://tinyurl.com/66s4gy

Page down to the bottom and see weird half-inch teeth engaging the
inch-pitch chain on the rear.

The front sprocket has normal inch-pitch teeth, so I wonder what the
explanation was?

I scrolled around in there and could not find the name (manufacturer)
of the bicycle. Do you know what it is other than circa 1889?

All I could find is:
----------------------------------------------------------------------
Lot: 40

1 19th c. hard tire safety 19th c. hard tire safety having fork hung
crank, retains orig. brakes, 30" wheels, new wooden grips, lamp
bracket, rear drop step, re-covered saddle, older restoration, pin
striped, replaced tire rubber. C. 1889, VG cond.

Estimate: 3,500.00 - 4,500.00
----------------------------------------------------------------------

Jobst Brandt

Dear Jobst,

It _may_ be a Sparkbrook, figure 253 on page 282 of Sharp:

http://books.google.com/books?id=CNw...page#PPA282,M1

Minimal text is on pages 280-281.

Incidentally, Sparkbrook made a left-hand drive cushion-tire safety in
1892 with a 3/4-inch chain:

"1892 SPARKBROOK London Special Safety Model gentleman’s cushion-tyred
safety bicycle. Left hand 3/4" drive chain. Nickle-plated bronze hubs
with direct spoking. Carries a candle lamp."

http://www.amberleymuseum.co.uk/spec...gramme2007.pdf

Cheers,

Carl Fogel

On Nov 1, 7:15*pm, Brian Huntley wrote:
On Nov 1, 8:43*pm, wrote:

Ignore the fork-hung crank in the no-down-tube frame:

http://www.auctionflex.com/showlot.a...4596&weventite...
orhttp://tinyurl.com/66s4gy

Page down to the bottom and see weird half-inch teeth engaging the
inch-pitch chain on the rear.

The front sprocket has normal inch-pitch teeth, so I wonder what the
explanation was?

I've never seen a good reason for the 'skip tooth' inch-pitch chain
and sprockets in the first place, Carl. Perhaps you have a link to
one.

The outboard bearings on the bb are interesting. A combination of
spindly-looking and functional seeming, assuming they'd protect them
somehow.

I wonder if they were meant to adapt crank/hub bearings made for
highwheelers. They look similar to bearings you find today on
unicycles.

-pm

Brian Huntley wrote:

Ignore the fork-hung crank in the no-down-tube frame:

http://tinyurl.com/66s4gy

Page down to the bottom and see weird half-inch teeth engaging the
inch-pitch chain on the rear.

The front sprocket has normal inch-pitch teeth, so I wonder what
the explanation was?

I've never seen a good reason for the 'skip tooth' inch-pitch chain
and sprockets in the first place, Carl. Perhaps you have a link to
one.

The outboard bearings on the BB are interesting. A combination of
spindly-looking and functional seeming, assuming they'd protect them
somehow.

Not long ago, track riders who had inch pitch sprockets, did so
because track bicycles were the last to use block chain, a chain in
which the roller pairs of inch pitch chain were a solid block of
steel, left over from the days before Renold offered roller chains.

http://tinyurl.com/6jwa3n

To accommodate inch pitch bicycles, the closely spaced rollers of an
inch pitch roller chain were offered. at the time of my first
bicycle, most of them were so equipped... except for English 3-speed
SA hub bicycles.

It took a while for the 3/32 wide roller, derailleur chain became
popular, there being no derailleurs commonly used at the time. We
were told that track sprinters were so strong that only block chain
was strong enough. I think that belief has faded away in the last 50
years. Tubular tires may take longer.

Jobst Brandt

On Nov 1, 6:43*pm, wrote:
Ignore the fork-hung crank in the no-down-tube frame:

http://www.auctionflex.com/showlot.a...4596&weventite....
orhttp://tinyurl.com/66s4gy

Page down to the bottom and see weird half-inch teeth engaging the
inch-pitch chain on the rear.

The front sprocket has normal inch-pitch teeth, so I wonder what the
explanation was?

Cheers,

Carl Fogel

I can't tell from the picture but perhaps the rear sprocket has an odd
number of teeth.

-pm

Carl Fogel wrote:

Ignore the fork-hung crank in the no-down-tube frame:

http://tinyurl.com/66s4gy

Page down to the bottom and see weird half-inch teeth engaging the
inch-pitch chain on the rear.

The front sprocket has normal inch-pitch teeth, so I wonder what the
explanation was?

I scrolled around in there and could not find the name (manufacturer)
of the bicycle. Do you know what it is other than circa 1889?

All I could find is:
----------------------------------------------------------------------
Lot: 40

1 19th c. hard tire safety 19th c. hard tire safety having fork hung
crank, retains orig. brakes, 30" wheels, new wooden grips, lamp
bracket, rear drop step, re-covered saddle, older restoration, pin
striped, replaced tire rubber. C. 1889, VG cond.

Estimate: 3,500.00 - 4,500.00
----------------------------------------------------------------------

It _may_ be a Sparkbrook, figure 253 on page 282 of Sharp:

http://books.google.com/books?id=CNw...page#PPA282,M1

Minimal text is on pages 280-281.

Incidentally, Sparkbrook made a left-hand drive cushion-tire safety
in 1892 with a 3/4-inch chain:

"1892 SPARKBROOK London Special Safety Model gentleman?s
cushion-tyred safety bicycle. Left hand 3/4" drive
chain. Nickle-plated bronze hubs with direct spoking. Carries a
candle lamp."

http://www.amberleymuseum.co.uk/spec...gramme2007.pdf

Thanks.

Interesting how they didn't see the toptube-downtube arrangement, but
chose to add a BB hanger, and maybe that is how that term still hangs
around in frame builders circles.

Jobst Brandt

On Sat, 1 Nov 2008 19:44:39 -0700 (PDT), pm
wrote:

On Nov 1, 7:15*pm, Brian Huntley wrote:
On Nov 1, 8:43*pm, wrote:

Ignore the fork-hung crank in the no-down-tube frame:

http://www.auctionflex.com/showlot.a...4596&weventite...
orhttp://tinyurl.com/66s4gy

Page down to the bottom and see weird half-inch teeth engaging the
inch-pitch chain on the rear.

The front sprocket has normal inch-pitch teeth, so I wonder what the
explanation was?

I've never seen a good reason for the 'skip tooth' inch-pitch chain
and sprockets in the first place, Carl. Perhaps you have a link to
one.

The outboard bearings on the bb are interesting. A combination of
spindly-looking and functional seeming, assuming they'd protect them
somehow.

I wonder if they were meant to adapt crank/hub bearings made for
highwheelers. They look similar to bearings you find today on
unicycles.

-pm

Dear Pm,

For what it's worth, many companies cobbled their early safeties
together with parts borrowed directly from their tricycles, which were
where chains and sprockets had been developing all along.

Sharp's title reminds us that tricycles were immensely more popular
back then.

Cheers,

Carl Fogel

On Sat, 1 Nov 2008 20:09:24 -0700 (PDT), pm
wrote:

On Nov 1, 6:43*pm, wrote:
Ignore the fork-hung crank in the no-down-tube frame:

http://www.auctionflex.com/showlot.a...4596&weventite...
orhttp://tinyurl.com/66s4gy

Page down to the bottom and see weird half-inch teeth engaging the
inch-pitch chain on the rear.

The front sprocket has normal inch-pitch teeth, so I wonder what the
explanation was?

Cheers,

Carl Fogel

I can't tell from the picture but perhaps the rear sprocket has an odd
number of teeth.

-pm

Dear Pm,

Hmmm . . . I can't tell, either:
http://tinyurl.com/66s4gy

The front is a 22-tooth inch-pitch sprocket. The rear looks as if it
would be an 11 tooth if it were inch-pitch.

You could have 23 half-inch teeth on the rear, which would be the
equivalent of an imaginary 11.5 tooth inch-pitch cog.

I don't know of anyone talking about such impressive fine-tuning of
the gear ratios at the start of the safety era on a hard-tire bike.

But an odd number of teeth in that arrangement would distribute the
cog wear over 23 teeth instead of 11 or 12 and last twice as long, so
maybe that's the explanation--a sneaky way to make the small rear
sprocket last much longer.

Cheers,

Carl Fogel