Fitting new bottom bracket

[Tim Woodall]

I've now removed the old bottom bracket. I'm now off to town for some copper grease and something to
eat and a glass or two of champagne to celebrate.

When I get back I will fit the new part. This is a shimano BB with a metal end as part of the BB and
a plastic end.

Should I grease the threads on the frame, the parts, or both?

Should I fit the plastic bit first or the actual BB first?

How tight should I do them. I have a torque wrench so "technical" answers easy to apply. But
otherwise, very tight, tight, fairly tight or just tight enough that you can't undo it by fingers
alone? Obviously the threading means that it shouldn't come undone in use so it could reasonably be
any of these.

Finally, do people remove their BB once a year and regrease them or do they accept a four hour
struggle occasionally when one needs replacing?

Regards,

Tim.

--
God said, "div D = rho, div B = 0, curl E = - @B/@t, curl H = J + @D/@t," and there was light.

http://tjw.hn.org/ http://www.locofungus.btinternet.co.uk/

 

[Tony W]

"Tim Woodall" <[email protected]> wrote in message
news:[email protected]...
> I've now removed the old bottom bracket. I'm now off to town for some copper grease and something
> to eat and a glass or two of champagne to celebrate.
>
> When I get back I will fit the new part. This is a shimano BB with a metal end as part of the BB
> and a plastic end.
>
> Should I grease the threads on the frame, the parts, or both?
>
> Should I fit the plastic bit first or the actual BB first?
>
> How tight should I do them. I have a torque wrench so "technical" answers easy to apply. But
> otherwise, very tight, tight, fairly tight or just tight enough that you can't undo it by fingers
> alone? Obviously the threading means that it shouldn't come undone in use so it could reasonably
> be any of these.
>
> Finally, do people remove their BB once a year and regrease them or do they accept a four hour
> struggle occasionally when one needs replacing?

Well done. Enjoy the champagne!!

The leaflet with the new BB will give you tightening torques -- but basically it is somewhere
between one and two gorillas I was very suspicious of applying quite as much gorilla to the
plastic bit.

Certainly grease the metal/metal contact. Not sure that it is necessary to grease the metal/plastic
as they can't corrode together.

I did the metal part first but I doubt it makes a lot of difference.

My policy is if it ain't broke don't fix it. I see little point in removing a sealed BB until
its buggered.

Have fun.

T

 

[Mr R@T \ -Lsqco]

"Tim Woodall" <[email protected]> wrote in message
news:[email protected]...
> I've now removed the old bottom bracket. I'm now off to town for some copper grease and
> something to eat

I know us cyclists are supposed to be a *bit* macho, but surely using copper grease as a condiment
and following it up with champagne (even *good* champagne) isn't going to agree with you? If you
carry on with such a diet, I would think you would be making stops for a "comfort break" every half
mile when you ride later today.

Wow - and I thought "pot belge" was *nasty* stuff. [1]

Seriously though, I think what you have purchased is a *sealed* bottom bracket, which shouldn't need
regreasing during its lifetime. when it is kaputt, it is just replaced with a new unit - the copper
grease is for the threads so you can take the unit out for replacement when that becomes necessary.
There is IIRC a tool you should use to assist with putting in the bracket, and the torque may be
listed in the leaflet which comes with the new one (although ICBW, as I mislaid the leaflet for mine
when I had it replaced last year).

Alex

 

[Tim Hall]

On Sat, 1 Mar 2003 13:01:02 +0000 (UTC), Tim Woodall <[email protected]> wrote:

>I've now removed the old bottom bracket. I'm now off to town for some copper grease and something
>to eat and a glass or two of champagne to celebrate.
>
>When I get back I will fit the new part. This is a shimano BB with a metal end as part of the BB
>and a plastic end.
>
>Should I grease the threads on the frame, the parts, or both?
>
>Should I fit the plastic bit first or the actual BB first?

You'll find one end (plastic I think) will pop off from the rest of the assembly. This equates to
the adjustable cup on your old cup and cone one. Clean the BB shell threads out with a blast of WD40
or paraffin. Add a dab of grease. Screw the whole unit into its hole (remember about left hand and
right hand threads). Do it up tight or until the metal shoulder hits the BB shell. Then screw the
plastic end on (remember again about LH and RH threads).
>
>How tight should I do them. I have a torque wrench so "technical" answers easy to apply. But
>otherwise, very tight, tight, fairly tight or just tight enough that you can't undo it by fingers
>alone? Obviously the threading means that it shouldn't come undone in use so it could reasonably be
>any of these.

I'd go for tight veering very tight. Do it up till it shears off then back it off a quarter turn.

The torque value may be stamped on the ends of the BB.

>Finally, do people remove their BB once a year and regrease them or do they accept a four hour
>struggle occasionally when one needs replacing?

Shimano sealed BB lasts forever, for various values of forever. Fit and forget.

Tim
--

fast and gripping, non pompous, glossy and credible.

 

[Peter B]

"Tim Woodall" <[email protected]> wrote in message
news:[email protected]...

> Should I grease the threads on the frame, the parts, or both?

Won't hurt if you do both. An alternative to copper grease, particularly on alu frames, is PTFE
tape. Available from the plumbing section of your local Buy & Queue.

Pete

 

[Pete Biggs]

Tim Woodall wrote:
> I've now removed the old bottom bracket. I'm now off to town for some copper grease and something
> to eat and a glass or two of champagne to celebrate.
>
> When I get back I will fit the new part. This is a shimano BB with a metal end as part of the BB
> and a plastic end.
>
> Should I grease the threads on the frame, the parts, or both?

Plenty on both frame and metal parts.

> Should I fit the plastic bit first or the actual BB first?
>
> How tight should I do them. I have a torque wrench so "technical" answers easy to apply. But
> otherwise, very tight, tight, fairly tight or just tight enough that you can't undo it by fingers
> alone? Obviously the threading means that it shouldn't come undone in use so it could reasonably
> be any of these.

See www.parktool.com/repair_help/FAQindex.shtml#bottom%20bracket for fitting instructions including
torque values.

> Finally, do people remove their BB once a year and regrease them or do they accept a four hour
> struggle occasionally when one needs replacing?

BB threads shouldn't need redoing if installed with grease. Bearings aren't designed to be
re-greased if it's a sealed cartridge unit.

~PB

 

[Simon Mason]

Tim Hall <[email protected]> wrote in message
news:<[email protected]>... ?
>
> Shimano sealed BB lasts forever, for various values of forever. Fit and forget.

I had mine done at a LBS in July 2001 for UKP 40. It needs doing again after an estimated 10
000 miles.

--
Simon Mason Anlaby, East Yorkshire. 53°44'N 0°26'W http://www.simonmason.karoo.net

 

[Just Zis Guy]

On Sat, 01 Mar 2003 15:48:25 +0000, Tim Hall <[email protected]> wrote:

>Shimano sealed BB lasts forever, for various values of forever.

Slightly under 5k miles, mine's worn out. It was a cheapie. Buy the better ones, say I.

Guy
===
** WARNING ** This posting may contain traces of irony. http://www.chapmancentral.com (BT ADSL and
dynamic DNS permitting)
NOTE: BT Openworld have now blocked port 25 (without notice), so old mail addresses may no longer
work. Apologies.

 

[Bob Flemming]

On Sun, 02 Mar 2003 19:47:15 +0000, "Just zis Guy, you know?" <[email protected]> wrote:

>On Sat, 01 Mar 2003 15:48:25 +0000, Tim Hall <[email protected]> wrote:
>
>>Shimano sealed BB lasts forever, for various values of forever.
>
>Slightly under 5k miles, mine's worn out. It was a cheapie. Buy the better ones, say I.

but would you also say that, as far as longevity goes, it's probably just as good to stick with the
old-fashioned cup and cone setup in comparison with these cheaper sealed units? Is there much to be
gained by changing?

so far loose bearings have performed ok.....

again, just a thought

cheers bob

 

[Pete Biggs]

Bob Flemming wrote:

>>> Shimano sealed BB lasts forever, for various values of forever.
>>
>> Slightly under 5k miles, mine's worn out. It was a cheapie. Buy the better ones, say I.
>
> but would you also say that, as far as longevity goes, it's probably just as good to stick with
> the old-fashioned cup and cone setup in comparison with these cheaper sealed units? Is there much
> to be gained by changing?

I'm not sure if it's worth changing for the sake of it, but most cheap sealed BB's survive a lot
more than 5k miles. They are cheap and easy to fit.

--
~PB FA: 62cm Ti frame: http://tinyurl.com/6stt

 

[Just Zis Guy]

On Mon, 03 Mar 2003 23:17:55 +0000, Bob Flemming <[email protected]> wrote:

>but would you also say that, as far as longevity goes, it's probably just as good to stick with the
>old-fashioned cup and cone setup in comparison with these cheaper sealed units? Is there much to be
>gained by changing?

A good quality cup and cone set lasts for a very long time, the only downside is the occasional
grease and tweak (maybe twice a year). For an on-road bike I think that's a good deal; for an MTB
I'd probably stick with sealed units. My original cup-and-cone bearings lasted fifteen years, but
the races got damaged which is the only reason I changed.

 

[Peter B]

"Bob Flemming" <[email protected]> wrote in message
news:[email protected]...
>>
> but would you also say that, as far as longevity goes, it's probably just as good to stick with
> the old-fashioned cup and cone setup in comparison with these cheaper sealed units? Is there much
> to be gained by changing?

Depends on your riding conditions. If you have to regularly strip down, clean and reassemble a loose
bearing set-up then changing to cartridge units will be a much cleaner and more convenient option.
If, however, you can go a few years without the strip down there won't be much in it.

Pete