NJS (Dura-Ace) thread standards

I'm involved in a disagreement with a member of a French fixed-gear
forum who insists that Dura-Ace NJS track sprockets (and by extension,
all NJS hubs and sprockets) have Italian (35mm x 24tpi) threads.

Of course, I think he's mistaken, but I haven't been able to find a
summary of the NJS standards (in English or Japanese). I'm away from
home and don't have access to my own hubs and sprockets to make the
necessary comparisons: the closest I've come to proving his error is a
picture of a Campagnolo track sprocket that's stamped "NJS" *and*
"BSC".

Can anyone point me to a summary of the NJS standards (specifically
the hub and sprocket thread standards) or confirm that Dura-Ace NJS
sprockets do indeed have BSC threads?

Thanks,

James Thomson

YoSnappyJ wrote:
I'm involved in a disagreement with a member of a French fixed-gear
forum who insists that Dura-Ace NJS track sprockets (and by extension,
all NJS hubs and sprockets) have Italian (35mm x 24tpi) threads.

Of course, I think he's mistaken, but I haven't been able to find a
summary of the NJS standards (in English or Japanese). I'm away from
home and don't have access to my own hubs and sprockets to make the
necessary comparisons: the closest I've come to proving his error is a
picture of a Campagnolo track sprocket that's stamped "NJS" *and*
"BSC".

Can anyone point me to a summary of the NJS standards (specifically
the hub and sprocket thread standards) or confirm that Dura-Ace NJS
sprockets do indeed have BSC threads?

My recollection is BSC but I can't fins a confirming link
either:

http://www.yellowjersey.org/photosfr...t/FWTHREAD.JPG

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

YoSnappyJ wrote:
I'm involved in a disagreement with a member of a French fixed-gear
forum who insists that Dura-Ace NJS track sprockets (and by extension,
all NJS hubs and sprockets) have Italian (35mm x 24tpi) threads.

Of course, I think he's mistaken, but I haven't been able to find a
summary of the NJS standards (in English or Japanese). I'm away from
home and don't have access to my own hubs and sprockets to make the
necessary comparisons: the closest I've come to proving his error is a
picture of a Campagnolo track sprocket that's stamped "NJS" *and*
"BSC".

Can anyone point me to a summary of the NJS standards (specifically
the hub and sprocket thread standards) or confirm that Dura-Ace NJS
sprockets do indeed have BSC threads?

Shimano HB-7600 are listed only as 1.37 x 24t and AFAIK they
are the only NJS hubs now.

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

On Nov 2, 10:30*am, AMuzi wrote:
YoSnappyJ wrote:
I'm involved in a disagreement with a member of a French fixed-gear
forum who insists that Dura-Ace NJS track sprockets (and by extension,
all NJS hubs and sprockets) have Italian (35mm x 24tpi) threads.

Of course, I think he's mistaken, but I haven't been able to find a
summary of the NJS standards (in English or Japanese). I'm away from
home and don't have access to my own hubs and sprockets to make the
necessary comparisons: the closest I've come to proving his error is a
picture of a Campagnolo track sprocket that's stamped "NJS" *and*
"BSC".

Can anyone point me to a summary of the NJS standards (specifically
the hub and sprocket thread standards) or confirm that Dura-Ace NJS
sprockets do indeed have BSC threads?

Shimano HB-7600 are listed only as 1.37 x 24t and AFAIK they
are the only NJS hubs now.

Btw, 1.37x24t = English; 36mmx24t - italian! Good Luck!

On Nov 2, 10:48*am, John Dacey wrote:
On Tue, 2 Nov 2010 09:33:04 -0700 (PDT), YoSnappyJ

wrote:
or confirm that Dura-Ace NJS
sprockets do indeed have BSC threads?

See the description for sprocket threads from Shimano's '97 catalogue:

http://businesscycles.com/graphics/s...og_trgroup.jpg

Here's a link to Shimano's website showing 2010 catalog:

http://cycle.shimano-eu.com/publish/...Ace_Track.html

Interestingly, they show pictures of hubs and sprockets, but no
specs....

Thanks for the input so far.

bfd wrote:

Btw, 1.37x24t = English; 36mmx24t - italian!

That's true of bottom bracket threads. Italian freewheel threads are
35mm x 24f though. Note the diagram that Andrew posted.

AMuzi wrote:

Shimano HB-7600 are listed only as 1.37 x 24t and AFAIK
they are the only NJS hubs now.

John Dacey wrote:

See the description for sprocket threads from Shimano's '97 catalogue:

http://businesscycles.com/graphics/s...og_trgroup.jpg

I think what I'm looking for, if possible, is an explicit link between
NJS hubs and BSC threads. The only specific mention of NJS on the '97
Shimano catalogue page is in the context of the bottom bracket. You
could argue that the absence of any specific mention of NJS sprockets
suggests that there's no distinction to be made, but there's also no
mention of NJS-specific hubs, and there are distinct NJS versions of
the 7600 rear hub with 110mm OLN and 8mm axle ends. Of course it's
also true that there was no specific market for NJS components outside
Japan in 1997, but that makes me curious about the inclusion of the
NJS bottom bracket.

Am I right in thinking that *all* Dura-Ace 1/8" sprockets bear the NJS
stamp?

bfd wrote:
On Nov 2, 10:48 am, John Dacey wrote:
On Tue, 2 Nov 2010 09:33:04 -0700 (PDT), YoSnappyJ

wrote:
or confirm that Dura-Ace NJS
sprockets do indeed have BSC threads?
See the description for sprocket threads from Shimano's '97 catalogue:

http://businesscycles.com/graphics/s...og_trgroup.jpg

Here's a link to Shimano's website showing 2010 catalog:

http://cycle.shimano-eu.com/publish/...Ace_Track.html

Interestingly, they show pictures of hubs and sprockets, but no
specs....

Yes, Shimano's printed materials have become difficult to
use. The 1997 book is a classic; still keep it at hand and
use it regularly.

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

YoSnappyJ wrote:
Thanks for the input so far.

bfd wrote:

Btw, 1.37x24t = English; 36mmx24t - italian!

That's true of bottom bracket threads. Italian freewheel threads are
35mm x 24f though. Note the diagram that Andrew posted.

AMuzi wrote:

Shimano HB-7600 are listed only as 1.37 x 24t and AFAIK
they are the only NJS hubs now.

John Dacey wrote:

See the description for sprocket threads from Shimano's '97 catalogue:

http://businesscycles.com/graphics/s...og_trgroup.jpg

I think what I'm looking for, if possible, is an explicit link between
NJS hubs and BSC threads. The only specific mention of NJS on the '97
Shimano catalogue page is in the context of the bottom bracket. You
could argue that the absence of any specific mention of NJS sprockets
suggests that there's no distinction to be made, but there's also no
mention of NJS-specific hubs, and there are distinct NJS versions of
the 7600 rear hub with 110mm OLN and 8mm axle ends. Of course it's
also true that there was no specific market for NJS components outside
Japan in 1997, but that makes me curious about the inclusion of the
NJS bottom bracket.

Am I right in thinking that *all* Dura-Ace 1/8" sprockets bear the NJS
stamp?

That's right DA 1/8" do, DA 3/32" do not.

Further, note that there is no point in NJS spec anywhere
outside of the Japanese Keirin Association (fashion
notwithstanding), not to be confused with the event called
keirin which is different and subject to UCI equipment rules.

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

On Nov 3, 9:30*pm, John Dacey wrote:

I strongly suspect that the codified specs for NJS parts that you seek
simply doesn't exist. As I understand it, NJS certification comes
only to those parts that have been specifically submitted for approval
to the governing body. That body grants approval (or not, as the case
may be).

The principal concern is that all parts of the bike are deemed
sufficiently reliable that the betting public remain assured that the
results of any race are not likely to be influenced by equipment
failure (or feigning such).

I think that's broadly true, but I understand that another aspect of
the certification is to establish uniformity of equipment, partly to
prevent any rider gaining a technical advantage, but also to maintain
broad intercompatibility between components. All NJS headsets are 1"
threaded, for example. All NJS handlebar clamps are 1". All NJS hubs
are 36-hole. I'd be astonished if thread norms weren't regulated, and
that being the case, I'd be astonished if they weren't BSC/ISO.

I cannot recall ever seeing a Shimano 1/8" sprocket that didn't have
the imprimatur of an NJS stamp, but it's not a detail I've looked for
many times (doesn't matter outside of professional parimutuel Keirin
racing).

Likewise. I've also noticed the NJS stamp on Dura-Ace lockrings.

I should probably make it clear that I don't have any particular
personal interest in NJS components, and I'm aware of their very
specific application in professional Keirin racing. I'm only
interested in resolving the question of whether or not NJS hubs use
BSC threads because a pundit on a certain Gallic forum is advising his
froggy bethren to avoid NJS-stamped Dura-Ace sprockets, or to match
them only with NJS hubs.

All the circumstantial evidence is that not only are *all* 1/8" Dura-
Ace sprockets NJS stamped, but that *all* NJS hubs and sprockets are
BSC-threaded. I'm trying to make the final step from being personally
convinced of the fact beyond all reasonable doubt, to providing
sufficient evidence to persuade somebody who's equally convinced of
the contrary.