BB Sizing question-- English threads and 70mm width?
 

I have an old Nishiki Olympic 12 on which I would like to change the
bottom bracket. However, I'm confused on the sizing for this
particular model.

It currently has an old non-cartrige bb bracket. I took that out, but
I don't know what size cartrige-type to replace it with. The threads
are definitely English (right side threads are left-handed and an
English-threaded Chorus bb I have fit into the threads on both sides
perfectly).

However the shell is definitely 70mm (checked with callipers and
compared directly to another bike with 68 mm shell). Do they make 70mm
bb's with English threads? I'm only aware of English in 68 and some 73
and Italian in 70.

One thing I thought of was that maybe the shell had never been faced
(I got the frame used, so I don't know the history). But I looked at
the spindle of the old bb, and it's really long, even though the bike
is a double, not a triple. The overall length (excluding the threads
on the ends) is about 128 mm, and the cones are substantially farther
apart than those on an old Ultegra spindle I have that came out of a
68mm shell.

This leads me to believe that the 70mm width is correct.

So the question is-- Is there a bb I can use in this shell? If not,
should I have my LBS face the shell? Or is it possible that the shell
is 70mm for some reason and should not be shortened?

Thanks,

Jim

BB Sizing question-- English threads and 70mm width?
 

I'd think a Phil Wood BB would work well regardless. Just get one with the
length axle you have now (or perhaps a bit shorter if you want) and use the
english thread lock rings. Also, you can swap out the Phil BB itself for a
Shimano UN-72 (Italian threaded @ 70mm) and it will fit the Phil lock rings
nicely once you remove the right side cup. This will save some money although
the Phil BB is likely to last far longer.

David

Jim Rogers wrote:

I have an old Nishiki Olympic 12 on which I would like to change the
bottom bracket. However, I'm confused on the sizing for this
particular model.

It currently has an old non-cartrige bb bracket. I took that out, but
I don't know what size cartrige-type to replace it with. The threads
are definitely English (right side threads are left-handed and an
English-threaded Chorus bb I have fit into the threads on both sides
perfectly).

However the shell is definitely 70mm (checked with callipers and
compared directly to another bike with 68 mm shell). Do they make 70mm
bb's with English threads? I'm only aware of English in 68 and some 73
and Italian in 70.

One thing I thought of was that maybe the shell had never been faced
(I got the frame used, so I don't know the history). But I looked at
the spindle of the old bb, and it's really long, even though the bike
is a double, not a triple. The overall length (excluding the threads
on the ends) is about 128 mm, and the cones are substantially farther
apart than those on an old Ultegra spindle I have that came out of a
68mm shell.

This leads me to believe that the 70mm width is correct.

So the question is-- Is there a bb I can use in this shell? If not,
should I have my LBS face the shell? Or is it possible that the shell
is 70mm for some reason and should not be shortened?

Thanks,

Jim

BB Sizing question-- English threads and 70mm width?
 

Jim Rogers wrote:

I have an old Nishiki Olympic 12 on which I would like to change the
bottom bracket. However, I'm confused on the sizing for this
particular model.

It currently has an old non-cartrige bb bracket. I took that out, but
I don't know what size cartrige-type to replace it with. The threads
are definitely English (right side threads are left-handed and an
English-threaded Chorus bb I have fit into the threads on both sides
perfectly).

However the shell is definitely 70mm (checked with callipers and
compared directly to another bike with 68 mm shell). Do they make 70mm
bb's with English threads? I'm only aware of English in 68 and some 73
and Italian in 70.

One thing I thought of was that maybe the shell had never been faced
(I got the frame used, so I don't know the history). But I looked at
the spindle of the old bb, and it's really long, even though the bike
is a double, not a triple. The overall length (excluding the threads
on the ends) is about 128 mm, and the cones are substantially farther
apart than those on an old Ultegra spindle I have that came out of a
68mm shell.

This leads me to believe that the 70mm width is correct.

So the question is-- Is there a bb I can use in this shell? If not,
should I have my LBS face the shell? Or is it possible that the shell
is 70mm for some reason and should not be shortened?

There were indeed 70mm BSC threaded BBs from Nishiki and
also Sekine. What is the spindle marking in your original, a
type 3-S or a 5-S? Three denotes a 68, five a 70mm shell.

For the one millimeter chainline error, I'd just install a
normal BSC BB and see what happens. I assume you do not want
to pay for frame machine service if you can help it.

If the gear train shifts well with a one millimeter right
offset ( and it most likely will) then you actually do not
have a problem, just a curiosity.
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

BB Sizing question-- English threads and 70mm width?
 

irene- It currently has an old non-cartrige bb bracket. I took that out, but
I don't know what size cartrige-type to replace it with. The threads
are definitely English BRBR
However the shell is definitely 70mm (checked with callipers and
compared directly to another bike with 68 mm shell). Do they make 70mm
bb's with English threads? I'm only aware of English in 68 and some 73
and Italian in 70. BRBR

No 70mm english BBs, it's just made poorly, IMO-If the chainline is not
affected hugely, just use a 68mm BB. Or have the BB shell faced a wee bit, a
good idea anyway, and it will be closer to 68mm.

BB spindles are matched to cranks. A long BB with a double designed for that is
not uncommon.



irene- So the question is-- Is there a bb I can use in this shell? If not,
should I have my LBS face the shell? Or is it possible that the shell
is 70mm for some reason and should not be shortened? BRBR

Have it faced and use the BB that matches the crank you wish to use.


Peter Chisholm
Vecchio's Bicicletteria
1833 Pearl St.
Boulder, CO, 80302
(303)440-3535
http://www.vecchios.com
"Ruote convenzionali costruite eccezionalmente bene"