rim notation
 

Today I saw a rear wheel rim with the
Torpedo 1SP hub. On the rim are the digits

20-635 18/8

* 20 can be the inner rim width in mm

* 635 is most likely the rim diameter and
familiar ISO/ETRTO tire designation, also
in mm

* 18 could be the number of spokes, as the rim
has 36 spokes (360 degree wheel) and 18*2=36
- but, the sprocket is 18T, so maybe that is
it?

* 8 - the sprocket diameter in cm? If so, the
"18T theory" is more likely.

--
underground experts united
http://user.it.uu.se/~embe8573

rim notation
 

Emanuel Berg wrote:
Today I saw a rear wheel rim with the
Torpedo 1SP hub. On the rim are the digits

Factory markings on a bicycle rim will not designate any sprocket dimension.

20-635 18/8

[trollian interpretations of "18/8"]

Smoke way less of that CO-producing stuff, instead, do finally order a
poster printed table of stainless steel qualities!

rim notation
 

Sepp Ruf wrote:

20-635 18/8

[trollian interpretations of "18/8"]

Smoke way less of that CO-producing stuff,
instead, do finally order a poster printed
table of stainless steel qualities!

I didn't now that in Germany you measure the
dick in chromium and nickel percentages...

--
underground experts united
http://user.it.uu.se/~embe8573

rim notation
 

On Sat, 10 Mar 2018 14:21:15 +0100, Emanuel Berg
wrote:

Sepp Ruf wrote:

20-635 18/8

[trollian interpretations of "18/8"]

Smoke way less of that CO-producing stuff,
instead, do finally order a poster printed
table of stainless steel qualities!

I didn't now that in Germany you measure the
dick in chromium and nickel percentages...

18-8 is a general designation for stainless steel having approximately
(not exactly) 18% chromium and 8% nickel.

The term is very none exact and can be used for almost any of the 300
series, 302, 302HQ, 303, 304, 305, 316, etc., which do have different
properties.
--
Cheers,

John B.

rim notation
 

John B. wrote:

18-8 is a general designation for stainless
steel having approximately (not exactly) 18%
chromium and 8% nickel.

The term is very none exact and can be used
for almost any of the 300 series, 302, 302HQ,
303, 304, 305, 316, etc., which do have
different properties.

OK, great!

I also found

18 Z 1/2"

on the sprocket. I suppose 18 is the number of
teeth, and 1/2" is the diameter of the wheel
axle hole .

On the hub shell, it says 36 which again
I suppose is the number of spokes (indeed
18*2=36), but it also says 2.8...?

Spokes are 2mm or 2.2mm at the elbow so perhaps
it is the spoke hole diameter in mm on the
hub flanges?

--
underground experts united
http://user.it.uu.se/~embe8573

rim notation
 

18 Z 1/2"

The Torpedo sprockets come in different
flavors. The 3SP (Triplex/Dreigang) I have are
19T, the Duomatic is 20T.

The letter "Z" is the German "Zahn" for
"tooth", plain and simple.

The Duomatic has a sprocket, or a

Zahnkranz 1/2 x 1/8" aufsteckbar

"aufsteckbar" is "attachable" so the inches
probably refers to something that has to do
with that.

It also says

(s. Liste Nr. 196.6/8)

anyone has that one lying around?

--
underground experts united
http://user.it.uu.se/~embe8573

rim notation
 

On 3/10/2018 10:30 PM, Emanuel Berg wrote:
18 Z 1/2"

The Torpedo sprockets come in different
flavors. The 3SP (Triplex/Dreigang) I have are
19T, the Duomatic is 20T.

The letter "Z" is the German "Zahn" for
"tooth", plain and simple.

The Duomatic has a sprocket, or a

Zahnkranz 1/2 x 1/8" aufsteckbar

"aufsteckbar" is "attachable" so the inches
probably refers to something that has to do
with that.


1/2 x 1/8" probably refers to the appropriate chain (which does have
these measurements; 1/2" from pin to pin, and roughly 1/8" wide.)

Mark J.

rim notation
 

Mark J. wrote:

1/2 x 1/8" probably refers to the appropriate
chain (which does have these measurements;
1/2" from pin to pin, and roughly 1/8" wide.)

Great, thanks!

--
underground experts united
http://user.it.uu.se/~embe8573

rim notation
 

On 3/11/2018 12:30 AM, Emanuel Berg wrote:
18 Z 1/2"

The Torpedo sprockets come in different
flavors. The 3SP (Triplex/Dreigang) I have are
19T, the Duomatic is 20T.

The letter "Z" is the German "Zahn" for
"tooth", plain and simple.

The Duomatic has a sprocket, or a

Zahnkranz 1/2 x 1/8" aufsteckbar

"aufsteckbar" is "attachable" so the inches
probably refers to something that has to do
with that.

It also says

(s. Liste Nr. 196.6/8)

anyone has that one lying around?


Oh dear lord. Really?

3-spline sprockets are cheap and ubiquitous. They're 'quick
change' in that the previous versions (mostly prewar) were
all screw-on track sprockets. Standard format fits Sturmey,
Shimano, SRAM-Sachs-F&S-Torpedo, Bendix, Durex, Centrix, and
so on right down to $5 chinese child's coaster hubs. You can
mix-n-match across brands and tooth count, change your
gearing every morning if you like, sizes range 13t to 24t.

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

rim notation
 

AMuzi wrote:

3-spline sprockets are cheap and ubiquitous.
They're 'quick change' in that the previous
versions (mostly prewar) were all screw-on
track sprockets. Standard format fits
Sturmey, Shimano, SRAM-Sachs-F&S-Torpedo,
Bendix, Durex, Centrix, and so on right down
to $5 chinese child's coaster hubs. You can
mix-n-match across brands and tooth count,
change your gearing every morning if you
like, sizes range 13t to 24t.

Another thing I have thought about doing is to
flip the sprocket which has an inclination and
is facing inwards by design/default, but
flipping it might be better than padding with
spacers/washers to get a better chain line, if
indeed it can be done without complications as
I suspect it can?

--
underground experts united
http://user.it.uu.se/~embe8573