BB Size Number Meanings - ALWAYS getting the wrong part!

I have an older bike that provided me with my first ever experience with
Al years ago, and went through some bottom bracket issues with it. The
original that came with the bike was the traditional type with
loose/removeable separate cups a sleeve in the center, independent
bearings, and an axle that developed a nasty pit in the bearing track.

I ran with it this way for a while until it started to get really bad
and I had to get a replacement from the LBS, I didn't have time to put
it together just then and when I did I realized that the spacing between
the bearing races were so far apart that the bottom bracket cups would
no longer even screw back in...the threads would still stick out 1/4" or
more. So I tossed that.

I had since moved and went to a *different* LBS, with all my original
bottom bracket bits and told that I was now in the world of the Shimano
"sealed cartridge unit" bottom bracket and that they didn't have
something there, but would order the right piece. I bought my new Park
install tool and the boxed Shimano part they had ordered. I once *again*
moved to another state.

When I finally got there and installed this bottom bracket I found that
the only way my bicycle would now fit the front crank was to make it a
double chainring. I was living in a flat part of the world now, so
losing the third front chainring wasn't a big deal at the time...upset
about the part but back on my wheels.

I now WANT that third chainring back because I'm living in a hilly area.
I removed the Shimano sealed BB and it is a BB-UN52, "68", BC 1.37x24. I
no longer have the original pitted axle, but the only thing I can find
on the original BB parts is "1.37x24T, JAPAN, TANGE".

So...I think the conclusion is that I need a "1.37x24" (not sure what
the numbers represent) and that it *needs* to be a "T"...which I can
only assume means TRIPLE...as in triple chainring.

Does this qualify me for the genius club?

Are there Shimano gurus whos know what part # I should *specifically*
tell my current LBS so they can't have ANY opportunity to muck this one
up? Will my Park bottom brack tool still work on today's Shimano sealed
cartridges?

Thanks all.

On Tue, 18 Apr 2006 14:31:03 -0600, Franz Bestuchev
wrote:

I have an older bike that provided me with my first ever experience with
Al years ago, and went through some bottom bracket issues with it. The
original that came with the bike was the traditional type with
loose/removeable separate cups a sleeve in the center, independent
bearings, and an axle that developed a nasty pit in the bearing track.

I ran with it this way for a while until it started to get really bad
and I had to get a replacement from the LBS, I didn't have time to put
it together just then and when I did I realized that the spacing between
the bearing races were so far apart that the bottom bracket cups would
no longer even screw back in...the threads would still stick out 1/4" or
more. So I tossed that.

I had since moved and went to a *different* LBS, with all my original
bottom bracket bits and told that I was now in the world of the Shimano
"sealed cartridge unit" bottom bracket and that they didn't have
something there, but would order the right piece. I bought my new Park
install tool and the boxed Shimano part they had ordered. I once *again*
moved to another state.

When I finally got there and installed this bottom bracket I found that
the only way my bicycle would now fit the front crank was to make it a
double chainring. I was living in a flat part of the world now, so
losing the third front chainring wasn't a big deal at the time...upset
about the part but back on my wheels.

I now WANT that third chainring back because I'm living in a hilly area.
I removed the Shimano sealed BB and it is a BB-UN52, "68", BC 1.37x24. I
no longer have the original pitted axle, but the only thing I can find
on the original BB parts is "1.37x24T, JAPAN, TANGE".

Measure the length of that old Tange shaft. If it's 122mm or close to
it, get a 68 x 122mm UN52; if it's closer to 127mm, then a 68x127 UN52
should do the trick. A lot of the cranks for the old-style BB setups
had a 122 (or even 127) shaft length.

So...I think the conclusion is that I need a "1.37x24" (not sure what
the numbers represent)

That's the thread diameter and pitch; the important thing is the
length.

and that it *needs* to be a "T"...which I can
only assume means TRIPLE...as in triple chainring.

Pfui. The BB knows not what's on it. The ltngth;s the thing, and
there are many possible lengths from 110 to 127mm. (Not all are
available in all models of BB, though.)

Does this qualify me for the genius club?

You have come far, Grasshopper, but there is still the challenge of
the rice paper yet to meet.

Are there Shimano gurus whos know what part # I should *specifically*
tell my current LBS so they can't have ANY opportunity to muck this one
up? Will my Park bottom brack tool still work on today's Shimano sealed
cartridges?

There are many that will work. The dimensions are the important part,
but there's one more gotcha. Don't slave yourself to Shimano, and if
you select that brand, watch out for the ones that have threads that
don't come all the way to the right-side flange; those are intended
for use with a special fder, and they'll bring you grief with a
regular setup. (I think those are UN53, but I may be misremembering.)
--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.

Franz Bestuchev wrote:
I removed the Shimano sealed BB and it is a BB-UN52, "68", BC 1.37x24.

BB-UN52 is Shimano's model number.
68 is the width of your frame's bb shell in millimeters. Italian
threaded frames are 70 mm wide, and many MTBs are 73.
BC may mean British Cut, but I'm not sure at all of that one.
1.37 is the thread diameter in inches, and 24 the thread pitch, in
threads-per-inche.

the only thing I can find on the original BB parts is "1.37x24T, JAPAN, TANGE".

Likewise, the threading, country of irigin and brand.

it *needs* to be a "T"...which I can
only assume means TRIPLE...as in triple chainring.

The T stands for thread, or tpi, or threads per inch, not for triple.

Are there Shimano gurus whos know what part # I should *specifically*
tell my current LBS so they can't have ANY opportunity to muck this one
up?

Depends on your crank make model and year. Check Sheldon's bb size
database:
http://www.sheldonbrown.com/bbsize.html

Will my Park bottom brack tool still work on today's Shimano sealed
cartridges?

There are several Park bottom bracket tools, some will work, some
won't. http://www.parktool.com/ may have photos or compatibility
listed.

Have fun!

Thanks all.

Werehatrack wrote:
On Tue, 18 Apr 2006 14:31:03 -0600, Franz Bestuchev
wrote:

I have an older bike that provided me with my first ever experience with
Al years ago, and went through some bottom bracket issues with it. The
original that came with the bike was the traditional type with
loose/removeable separate cups a sleeve in the center, independent
bearings, and an axle that developed a nasty pit in the bearing track.

I ran with it this way for a while until it started to get really bad
and I had to get a replacement from the LBS, I didn't have time to put
it together just then and when I did I realized that the spacing between
the bearing races were so far apart that the bottom bracket cups would
no longer even screw back in...the threads would still stick out 1/4" or
more. So I tossed that.

I had since moved and went to a *different* LBS, with all my original
bottom bracket bits and told that I was now in the world of the Shimano
"sealed cartridge unit" bottom bracket and that they didn't have
something there, but would order the right piece. I bought my new Park
install tool and the boxed Shimano part they had ordered. I once *again*
moved to another state.

When I finally got there and installed this bottom bracket I found that
the only way my bicycle would now fit the front crank was to make it a
double chainring. I was living in a flat part of the world now, so
losing the third front chainring wasn't a big deal at the time...upset
about the part but back on my wheels.

I now WANT that third chainring back because I'm living in a hilly area.
I removed the Shimano sealed BB and it is a BB-UN52, "68", BC 1.37x24. I
no longer have the original pitted axle, but the only thing I can find
on the original BB parts is "1.37x24T, JAPAN, TANGE".

Measure the length of that old Tange shaft. If it's 122mm or close to
it, get a 68 x 122mm UN52; if it's closer to 127mm, then a 68x127 UN52
should do the trick. A lot of the cranks for the old-style BB setups
had a 122 (or even 127) shaft length.

Unfortunately I don't have the shaft. I have the 2 old BB cups, the old
bearings and the wrong size Shimano sealed BB. That's all...



So...I think the conclusion is that I need a "1.37x24" (not sure what
the numbers represent)

That's the thread diameter and pitch; the important thing is the
length.

and that it *needs* to be a "T"...which I can
only assume means TRIPLE...as in triple chainring.

Pfui. The BB knows not what's on it. The ltngth;s the thing, and
there are many possible lengths from 110 to 127mm. (Not all are
available in all models of BB, though.)

This is beginning to sound like I have to ride around town trying part
after part to see what fits...


Does this qualify me for the genius club?

You have come far, Grasshopper, but there is still the challenge of
the rice paper yet to meet.

Are there Shimano gurus whos know what part # I should *specifically*
tell my current LBS so they can't have ANY opportunity to muck this one
up? Will my Park bottom brack tool still work on today's Shimano sealed
cartridges?

There are many that will work. The dimensions are the important part,
but there's one more gotcha. Don't slave yourself to Shimano, and if
you select that brand, watch out for the ones that have threads that
don't come all the way to the right-side flange; those are intended
for use with a special fder, and they'll bring you grief with a
regular setup. (I think those are UN53, but I may be misremembering.)

I don't really care who makes the thing, it's for an RX100 triple crank.
So it's going to be connecting to Shimano on one end, but as far as
what's in the middle...that just has to be affordable, and sized correctly.

wrote:
Franz Bestuchev wrote:
I removed the Shimano sealed BB and it is a BB-UN52, "68", BC 1.37x24.

BB-UN52 is Shimano's model number.
68 is the width of your frame's bb shell in millimeters. Italian
threaded frames are 70 mm wide, and many MTBs are 73.
BC may mean British Cut, but I'm not sure at all of that one.
1.37 is the thread diameter in inches, and 24 the thread pitch, in
threads-per-inche.

.....ohh...it would *probably* be helpful if I had included info about
the bike, d'oh.

It's a Trek 1100. The last year for the 1100, with the Easton E9
aluminum frame - the year after they only offered the 1200 with the same
frame and then the 1000. Drivetrain is all RX100.


the only thing I can find on the original BB parts is "1.37x24T, JAPAN, TANGE".

Likewise, the threading, country of irigin and brand.

it *needs* to be a "T"...which I can
only assume means TRIPLE...as in triple chainring.

The T stands for thread, or tpi, or threads per inch, not for triple.

Are there Shimano gurus whos know what part # I should *specifically*
tell my current LBS so they can't have ANY opportunity to muck this one
up?

Depends on your crank make model and year. Check Sheldon's bb size
database:
http://www.sheldonbrown.com/bbsize.html

Will be doing.


Will my Park bottom brack tool still work on today's Shimano sealed
cartridges?

There are several Park bottom bracket tools, some will work, some
won't. http://www.parktool.com/ may have photos or compatibility
listed.

Have fun!

Thanks all.

On Tue, 18 Apr 2006 21:51:18 -0600, Franz Bestuchev
wrote:
Werehatrack wrote:

Measure the length of that old Tange shaft. If it's 122mm or close to
it, get a 68 x 122mm UN52; if it's closer to 127mm, then a 68x127 UN52
should do the trick. A lot of the cranks for the old-style BB setups
had a 122 (or even 127) shaft length.

Unfortunately I don't have the shaft. I have the 2 old BB cups, the old
bearings and the wrong size Shimano sealed BB. That's all...

Shouldn't have thrown the old bit away then.

Pfui. The BB knows not what's on it. The ltngth;s the thing, and
there are many possible lengths from 110 to 127mm. (Not all are
available in all models of BB, though.)

This is beginning to sound like I have to ride around town trying part
after part to see what fits...

Measure how long your current shimano BB is and add to that how far extra
to the right your crank should go, times two (length added goes both right
and left), and then take as close as you can get to that.

Jasper

Franz Bestuchev wrote:
wrote:
Franz Bestuchev wrote:
I removed the Shimano sealed BB and it is a BB-UN52, "68", BC 1.37x24.

BB-UN52 is Shimano's model number.
68 is the width of your frame's bb shell in millimeters. Italian
threaded frames are 70 mm wide, and many MTBs are 73.
BC may mean British Cut, but I'm not sure at all of that one.
1.37 is the thread diameter in inches, and 24 the thread pitch, in
threads-per-inche.

....ohh...it would *probably* be helpful if I had included info about
the bike, d'oh.

It's a Trek 1100. The last year for the 1100, with the Easton E9
aluminum frame - the year after they only offered the 1200 with the same
frame and then the 1000. Drivetrain is all RX100.

Franz,

Sometimes it is best to start at the beginning. Get ahold of TREK, and
ask their tech folks what bb spindle size was spec'd on your bike.
I've found that most mfr's are all too happy to give you that info.
Armed with the original spindles size, you can then go to your current
LBS and get the proper parts. Look hard enough on the 'net and you may
even find the original cup and cone BB in a box somewhere, or if you
are flush go for a Phil Woods (will outlast your bike).

Happy hunting

//jtd//

Franz Bestuchev wrote:

It's a Trek 1100. The last year for the 1100, with the Easton E9
aluminum frame - the year after they only offered the 1200 with the same
frame and then the 1000. Drivetrain is all RX100.


OK- you've got an RX 100 triple crank, and the old BB was English
thread. According to Sheldon's data:
http://www.sheldonbrown.com/bbsize.html#rx100 , you should use a BB
with a 122.5mm length spindle. I think that's what you said you had in
the first place. Didn't it work?

Jeff