Octalink Bottom Bracket

"Gags" <gags_44nospamatnospamtpg.com.au> wrote in message
news:[email hidden]...

Quoted message said:

Question for those in the know........

I am replacing the drivetrain on my MTB and I want to replace the current
square taper BB with an Octalink one. I currently have a Shimano BB-UN40
that is 68-110mm. I have looked at a couple of places on the web and the
closest size that I can find for either an ES-51 or ES-71 hollowtech BB is
68-113mm.

I assume that this means that the BB is 3mm wider than the one I am
currently running??

Can I get one of these and then fit it to my bike or will the extra 3mm
make
this impossible??

Also, do I need another tool to insert/remove a hollowtech BB or can I use
the same one that I do now for the square taper BB??

Um, I don't know if I'm stating the obvious, but if you are wanting to
change the Bottom Bracket you'll also need new cranks, as an octalink shape
doesn't go into a square hole! When you buy new cranks, buy the bottom
bracket to match the cranks. Your existing BB won't have any bearing on the
size of the new one, except the '68'mm measurement (which is bottom bracket
shell width, i.e. set by your frame) So you will need a 68-*SOMETHING* to
match the cranks.

Cheers
Gemma

Gags said:

Question for those in the know........

I am replacing the drivetrain on my MTB and I want to replace the current
square taper BB with an Octalink one. I currently have a Shimano BB-UN40

Sheldon brown is usually helpful. try this:

http://www.sheldonbrown.com/bbsize.html

Quoted message said:

Can I get one of these and then fit it to my bike or will the extra 3mm make
this impossible??

I havn't tried it, but can't imagine why it would eb a problem.
Your feet will be a little futher apart though. :-)

"Mike" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Gags said:

Question for those in the know........

I am replacing the drivetrain on my MTB and I want to replace the

current

Quoted message said:

Quoted message said:

square taper BB with an Octalink one. I currently have a Shimano

BB-UN40

Quoted message said:

Sheldon brown is usually helpful. try this:

http://www.sheldonbrown.com/bbsize.html

Quoted message said:

Can I get one of these and then fit it to my bike or will the extra 3mm

make

Quoted message said:

Quoted message said:

this impossible??

I havn't tried it, but can't imagine why it would eb a problem.
Your feet will be a little futher apart though. :-)

It can be a big problem. I had a BB axle that was 3mm too wide and the
front derailer couldn't cope with the offset. The quickest way to tell if
the BB is the wrong width for the derailer is that the limit screws on the
front derailer will be at very uneven heights.
If you go too narrow you may find your big chainring rubbing on the frame
when spriniting / climbing.

"Mike" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Gags said:

Question for those in the know........

I am replacing the drivetrain on my MTB and I want to replace the

current

Quoted message said:

Quoted message said:

square taper BB with an Octalink one. I currently have a Shimano

BB-UN40

Quoted message said:

Sheldon brown is usually helpful. try this:

http://www.sheldonbrown.com/bbsize.html

Quoted message said:

Can I get one of these and then fit it to my bike or will the extra 3mm

make

Quoted message said:

Quoted message said:

this impossible??

I havn't tried it, but can't imagine why it would eb a problem.
Your feet will be a little futher apart though. :-)

It can be a big problem. I had a BB axle that was 3mm too wide and the
front derailer couldn't cope with the offset. The quickest way to tell if
the BB is the wrong width for the derailer is that the limit screws on the
front derailer will be at very uneven heights.
If you go too narrow you may find your big chainring rubbing on the frame
when spriniting / climbing.

"Duncan" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

"Mike" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Gags said:

Question for those in the know........

I am replacing the drivetrain on my MTB and I want to replace the

current

Quoted message said:

Quoted message said:

square taper BB with an Octalink one. I currently have a Shimano

BB-UN40

Quoted message said:

Sheldon brown is usually helpful. try this:

http://www.sheldonbrown.com/bbsize.html

Quoted message said:

Can I get one of these and then fit it to my bike or will the extra

3mm

Quoted message said:

make

Quoted message said:

Quoted message said:

this impossible??

I havn't tried it, but can't imagine why it would eb a problem.
Your feet will be a little futher apart though. :-)

It can be a big problem. I had a BB axle that was 3mm too wide and the
front derailer couldn't cope with the offset. The quickest way to tell if
the BB is the wrong width for the derailer is that the limit screws on the
front derailer will be at very uneven heights.
If you go too narrow you may find your big chainring rubbing on the frame
when spriniting / climbing.

I got an answer from a techo at Shimano who informs me that the 113mm should
be OK as the octalink system requires more of the BB spindle to insert into
the cranks and so 113mm octalink is equiv to 110mm square taper.

Gags