G
George L. Porte
Guest
I recently decided to play around with my old Bridgestone MB-6 and put together a cheap singlespeed
with some parts that I have in the mostly used box. I wanted to change out the 10 yr old bottom
bracket and make sure it was the right one for the crank I was going to use. I got the old one out
but it wasn't easy. The cheap plastic cap was all broken up but it came out.
I looked at the thread and on the drive side there was one spot that didn't look perfect but overall
it looked OK. I wanted to make sure so I measured how far in the questionable spot was and it was
about 13mm. The old bottom bracket that I had only had about 10mm of thread so I figured it would be
OK. I took it by the shop to see what they thought and they screwed one in and said it should be OK.
I asked how much to chase the threads and they said $30. They said that it wouldn't really be worth
it with this old MB-6. I got a new BB of the correct size and went on home.
I got home and put the cartridge in the drive side and then tried to put the cap in. I wouldn't go.
I took the cartridge out and screwed the cap in OK. I then took the old crappy BB which screws into
the non drive side and it went in OK too. I can't get both sides in together but separately is OK. I
notice that when I thread the old one in the non-drive side the BB cartridge is concentric with the
shell. When I thread the new one in the drive side, it is not concentric and is almost touching the
bottom of the shell. I also took out the bottom cable guide screw thinking that might be the problem
but it seems like the the shell is either not threaded right or bent. There doesn't appear to be any
damage to the shell. I suppose the old BB which threaded into the non-drive (straight) side was less
susceptable to the maladjusted (malthreaded) drive side because the cap is shorter and the
misalignment is less noticeable with a shorter part.
Is there a fix for this and is it worth fixing? The bike is a Bridgestone MB-6 (Tange frame).
Thanks GP
with some parts that I have in the mostly used box. I wanted to change out the 10 yr old bottom
bracket and make sure it was the right one for the crank I was going to use. I got the old one out
but it wasn't easy. The cheap plastic cap was all broken up but it came out.
I looked at the thread and on the drive side there was one spot that didn't look perfect but overall
it looked OK. I wanted to make sure so I measured how far in the questionable spot was and it was
about 13mm. The old bottom bracket that I had only had about 10mm of thread so I figured it would be
OK. I took it by the shop to see what they thought and they screwed one in and said it should be OK.
I asked how much to chase the threads and they said $30. They said that it wouldn't really be worth
it with this old MB-6. I got a new BB of the correct size and went on home.
I got home and put the cartridge in the drive side and then tried to put the cap in. I wouldn't go.
I took the cartridge out and screwed the cap in OK. I then took the old crappy BB which screws into
the non drive side and it went in OK too. I can't get both sides in together but separately is OK. I
notice that when I thread the old one in the non-drive side the BB cartridge is concentric with the
shell. When I thread the new one in the drive side, it is not concentric and is almost touching the
bottom of the shell. I also took out the bottom cable guide screw thinking that might be the problem
but it seems like the the shell is either not threaded right or bent. There doesn't appear to be any
damage to the shell. I suppose the old BB which threaded into the non-drive (straight) side was less
susceptable to the maladjusted (malthreaded) drive side because the cap is shorter and the
misalignment is less noticeable with a shorter part.
Is there a fix for this and is it worth fixing? The bike is a Bridgestone MB-6 (Tange frame).
Thanks GP