70mm English-threaded bottom bracket

[Stephen Greenwood]

I just bought an old Bridgestone MB-2 (1986 model, I believe) which I'm
converting into a fixed-gear commuter. The bottom bracket shell is 70mm
wide, and the existing cup-and-cone bottom bracket is marked with '
1.37" x 24 tpi '. Older threads on this newsgroup indicate that this is
British threading.

I'd like to replace this bottom bracket with the modern cartridge
variety, but I'm having difficulty finding ones that are both 70mm and
British-threaded. (British-threaded usually come in 68mm or 73mm, and
70mm ones usually have Italian threads.) The only one I've seen online
is a Campagnolo Veloce that comes with 111mm spindle. However, I plan
to use different bottom bracket spindle lengths as the mechanism for
adjusting the chainline [1], and I'd like to find some that come in
other spindle lengths. Can anyone point me to some? Alternatively, is
it possible to use a 73mm BB with spacers? Or a 68mm BB with only
partial thread engagement? Or perhaps there's a better solution I have
not considered.

Thanks for your time.

[1] I will use a flip-flop hub, and cannot adjust the chainline with
spacers and re-dishing the wheel.

[Jay Beattie]

Post by Stephen Greenwood
I just bought an old Bridgestone MB-2 (1986 model, I believe) which I'm
converting into a fixed-gear commuter. The bottom bracket shell is 70mm
wide, and the existing cup-and-cone bottom bracket is marked with '
1.37" x 24 tpi '. Older threads on this newsgroup indicate that this is
British threading.
I'd like to replace this bottom bracket with the modern cartridge
variety, but I'm having difficulty finding ones that are both 70mm and
British-threaded. (British-threaded usually come in 68mm or 73mm, and
70mm ones usually have Italian threads.) The only one I've seen online
is a Campagnolo Veloce that comes with 111mm spindle. However, I plan
to use different bottom bracket spindle lengths as the mechanism for
adjusting the chainline [1], and I'd like to find some that come in
other spindle lengths. Can anyone point me to some? Alternatively, is
it possible to use a 73mm BB with spacers? Or a 68mm BB with only
partial thread engagement? Or perhaps there's a better solution I have
not considered.

Phil Wood. He uses the same BB for 68/70 and it is installed with
rings that do not rest on the BB shell, so you can move the BB to
adjust your chainline, which is helpful on a fixed gear. Phil is
expensive, though. -- Jay Beattie.

[Kurd]

Unless the B.O.B. knows otherwise I believe you have a 68mm bottom bracket
shell.
Are you measuring just the frame or any parts of the bototm bracket sticking
out of it?

Post by Stephen Greenwood
I just bought an old Bridgestone MB-2 (1986 model, I believe) which I'm
converting into a fixed-gear commuter. The bottom bracket shell is 70mm
wide, and the existing cup-and-cone bottom bracket is marked with '
1.37" x 24 tpi '. Older threads on this newsgroup indicate that this is
British threading.
I'd like to replace this bottom bracket with the modern cartridge
variety, but I'm having difficulty finding ones that are both 70mm and
British-threaded. (British-threaded usually come in 68mm or 73mm, and
70mm ones usually have Italian threads.) The only one I've seen online
is a Campagnolo Veloce that comes with 111mm spindle. However, I plan
to use different bottom bracket spindle lengths as the mechanism for
adjusting the chainline [1], and I'd like to find some that come in
other spindle lengths. Can anyone point me to some? Alternatively, is
it possible to use a 73mm BB with spacers? Or a 68mm BB with only
partial thread engagement? Or perhaps there's a better solution I have
not considered.
Thanks for your time.
[1] I will use a flip-flop hub, and cannot adjust the chainline with
spacers and re-dishing the wheel.

[Chris]

As I recall the metric equivalent to the English threading is the same for
an IT BB, except the drive side cup is right hand threaded. So check that
too to make sure you have a BSC not an ITL BB

Post by Kurd
Unless the B.O.B. knows otherwise I believe you have a 68mm bottom bracket
shell.
Are you measuring just the frame or any parts of the bototm bracket sticking
out of it?

Post by Stephen Greenwood
I just bought an old Bridgestone MB-2 (1986 model, I believe) which I'm
converting into a fixed-gear commuter. The bottom bracket shell is 70mm
wide, and the existing cup-and-cone bottom bracket is marked with '
1.37" x 24 tpi '. Older threads on this newsgroup indicate that this is
British threading.
I'd like to replace this bottom bracket with the modern cartridge
variety, but I'm having difficulty finding ones that are both 70mm and
British-threaded. (British-threaded usually come in 68mm or 73mm, and
70mm ones usually have Italian threads.) The only one I've seen online
is a Campagnolo Veloce that comes with 111mm spindle. However, I plan
to use different bottom bracket spindle lengths as the mechanism for
adjusting the chainline [1], and I'd like to find some that come in
other spindle lengths. Can anyone point me to some? Alternatively, is
it possible to use a 73mm BB with spacers? Or a 68mm BB with only
partial thread engagement? Or perhaps there's a better solution I have
not considered.
Thanks for your time.
[1] I will use a flip-flop hub, and cannot adjust the chainline with
spacers and re-dishing the wheel.

[Booker C. Bense]

-----BEGIN PGP SIGNED MESSAGE-----

Post by Chris
As I recall the metric equivalent to the English threading is the same for
an IT BB, except the drive side cup is right hand threaded. So check that
too to make sure you have a BSC not an ITL BB

_ This is wrong.

Italian is just a tiny bit larger. 36mm x 24tpi.
BSC (1.375 inches or 34.925mm) x 24tpi

_ Booker C. Bense

[John Thompson]

Post by Booker C. Bense

Post by Chris
As I recall the metric equivalent to the English threading is the same for
an IT BB, except the drive side cup is right hand threaded. So check that
too to make sure you have a BSC not an ITL BB

_ This is wrong.
Italian is just a tiny bit larger. 36mm x 24tpi.
BSC (1.375 inches or 34.925mm) x 24tpi

True, but that silly millimeter larger is just enough to prevent the
threads of an English BB from engaging an Italian BB shell.

[Stephen Greenwood]

Post by Kurd
Unless the B.O.B. knows otherwise I believe you have a 68mm bottom bracket
shell.
Are you measuring just the frame or any parts of the bototm bracket sticking
out of it?

I'm measuring just the frame, not the lockrings or anything else. I
used a precision caliper, and I just checked it again -- it's 70.0 mm.

[Werehatrack]

On 15 Aug 2006 16:37:32 -0700, "Stephen Greenwood"

Post by Stephen Greenwood
I just bought an old Bridgestone MB-2 (1986 model, I believe) which I'm
converting into a fixed-gear commuter. The bottom bracket shell is 70mm
wide, and the existing cup-and-cone bottom bracket is marked with '
1.37" x 24 tpi '. Older threads on this newsgroup indicate that this is
British threading.
I'd like to replace this bottom bracket with the modern cartridge
variety, but I'm having difficulty finding ones that are both 70mm and
British-threaded. (British-threaded usually come in 68mm or 73mm, and
70mm ones usually have Italian threads.) The only one I've seen online
is a Campagnolo Veloce that comes with 111mm spindle. However, I plan
to use different bottom bracket spindle lengths as the mechanism for
adjusting the chainline [1], and I'd like to find some that come in
other spindle lengths. Can anyone point me to some? Alternatively, is
it possible to use a 73mm BB with spacers? Or a 68mm BB with only
partial thread engagement? Or perhaps there's a better solution I have
not considered.

If the threads go far enough into the BB shell, you can just use a
68mm BB; you'll get full thread engagement. In fact, the left
retainer will go all the way into the shell. The BB will run 1mm off
center to the right, which shouldn't hurt anything when it comes to
getting the chainline set where you want it.

[Stephen Greenwood]

Post by Werehatrack
If the threads go far enough into the BB shell, you can just use a
68mm BB; you'll get full thread engagement. In fact, the left
retainer will go all the way into the shell. The BB will run 1mm off
center to the right, which shouldn't hurt anything when it comes to
getting the chainline set where you want it.

Thanks, Werehatrack, that should probably work. I installed a Shimano
cartridge BB a few years ago, but had forgotten that the left side
didn't have some sort of ring that abuts the BB shell.

As for Phil Wood's BBs (suggested by Jay Beattie), they certainly seem
technically superior, but using a run-of-the-mill model is more
appropriate for what's meant to be a budget bike. Still, I appreciate
knowing about this option, so thank you, too, Jay.

[Qui si parla Campagnolo]

Post by Stephen Greenwood
I just bought an old Bridgestone MB-2 (1986 model, I believe) which I'm
converting into a fixed-gear commuter. The bottom bracket shell is 70mm
wide, and the existing cup-and-cone bottom bracket is marked with '
1.37" x 24 tpi '. Older threads on this newsgroup indicate that this is
British threading.
I'd like to replace this bottom bracket with the modern cartridge
variety, but I'm having difficulty finding ones that are both 70mm and
British-threaded. (British-threaded usually come in 68mm or 73mm, and
70mm ones usually have Italian threads.) The only one I've seen online
is a Campagnolo Veloce that comes with 111mm spindle. However, I plan
to use different bottom bracket spindle lengths as the mechanism for
adjusting the chainline [1], and I'd like to find some that come in
other spindle lengths. Can anyone point me to some? Alternatively, is
it possible to use a 73mm BB with spacers? Or a 68mm BB with only
partial thread engagement? Or perhaps there's a better solution I have
not considered.
Thanks for your time.
[1] I will use a flip-flop hub, and cannot adjust the chainline with
spacers and re-dishing the wheel.

Frame BB shell has never been faced is all...Take it to a good shop and
do same...get it to 68mm.

[Jim Rogers]

Post by Stephen Greenwood
I just bought an old Bridgestone MB-2 (1986 model, I believe) which I'm
converting into a fixed-gear commuter. The bottom bracket shell is 70mm
wide, and the existing cup-and-cone bottom bracket is marked with '
1.37" x 24 tpi '. Older threads on this newsgroup indicate that this is
British threading.

70mm English threaded BB's do exist. I have some old Nishiki frames
that had them and it threw me for a loop as well. I posted a question
about it on this group and the consensus answer was to have the shell
faced to 68mm and use a standard BB. See:

http://groups.google.com/group/rec.bicycles.tech/browse_frm/thread/8f20b84b9b1869d2/3130d43c0b067846?lnk=gst&q=Rogers+70mm&rnum=1#3130d43c0b067846

I did so and have been very happy with the results.

--Jim Rogers