Any ideas what bottom bracket fits a '85 GT Outpost MTB?

[Kevin]

My '85 GT Outpost has finally given up the ghost after 20 years of
service. The bottom bracket crunched last night and stopped rotating.
Does anyone know which reasonably priced bracket would fit? I generally
use the bike for touring but it's been pressed into service on the
commute due to my brompton being out of service.

Kevin.

 

[Bryan]

My '85 GT Outpost has finally given up the ghost after 20 years of
service. The bottom bracket crunched last night and stopped rotating.
Does anyone know which reasonably priced bracket would fit? I generally
use the bike for touring but it's been pressed into service on the
commute due to my brompton being out of service.

Kevin.

Take the axle out and measure it, then a UN53 or UN73.

UN53 118 mm axle is £14 from chainreaction and UN73 is £18. the UN73, should last you at least another 10 years, maybe 20 ;-)

Bryan

 

[Clive George]

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

> UN53 118 mm axle is £14 from chainreaction and UN73 is £18. the UN73,
> should last you at least another 10 years, maybe 20 ;-)

Yeah, you would hope so, wouldn't you? Knackered the UN72 on the front of
the tandem in very short order. The UN52 on the back, which gets more load,
was still fine.

cheers,
clive

 

[Sandy Morton]

In article <[email protected]>, Bryan
<[email protected]> wrote:
> Take the axle out and measure it, then a UN53 or UN73.

> UN53 118 mm axle is £14 from chainreaction and UN73 is £18. the
> UN73, should last you at least another 10 years, maybe 20 ;-)

You could buy a sealed unit for less than that.

--
A T (Sandy) Morton
on the Bicycle Island
In the Global Village
http://www.millport.net

 

[Pete Biggs]

Sandy Morton wrote:
> In article <[email protected]>, Bryan
> <[email protected]> wrote:
>> Take the axle out and measure it, then a UN53 or UN73.
>
>> UN53 118 mm axle is £14 from chainreaction and UN73 is £18. the
>> UN73, should last you at least another 10 years, maybe 20 ;-)
>
> You could buy a sealed unit for less than that.

UN53 and 73 are sealed units. Cheaper models may be heavier or not have
such good bearings.

Kevin, What crankset does the bike have?

~PB

 

[Pete Biggs]

Clive George wrote:
> "Bryan" <[email protected]> wrote in message
> news:[email protected]...
>
>> UN53 118 mm axle is £14 from chainreaction and UN73 is £18. the
>> UN73, should last you at least another 10 years, maybe 20 ;-)
>
> Yeah, you would hope so, wouldn't you? Knackered the UN72 on the
> front of the tandem in very short order. The UN52 on the back, which
> gets more load, was still fine.

That's probably more to do with differences with how it was fitted or the
bike/load than the model of BB.

~PB

 

[Clive George]

"Pete Biggs" <[email protected]> wrote in
message news:[email protected]...
> Clive George wrote:
>> "Bryan" <[email protected]> wrote in message
>> news:[email protected]...
>>
>>> UN53 118 mm axle is £14 from chainreaction and UN73 is £18. the
>>> UN73, should last you at least another 10 years, maybe 20 ;-)
>>
>> Yeah, you would hope so, wouldn't you? Knackered the UN72 on the
>> front of the tandem in very short order. The UN52 on the back, which
>> gets more load, was still fine.
>
> That's probably more to do with differences with how it was fitted or the
> bike/load than the model of BB.

No, in this case it's because the particular BB was ****. I mentioned the
bike/load thing (you can see it in the bit we've quoted) since it was
relevant - the BB with the higher load (the rear one) was a UN52 and was
still fine while the UN72 was dead. Both fitted at the same time. You'll
have to take my word that they were both fitted properly. (actually the UN52
wasn't - it's a 73mm BB in a 68mm shell with a 68mm spacer/mount/whatever -
but that's deliberate cos the LH and RH cranks are different makes).

cheers,
clive

 

[Pete Biggs]

Clive George wrote:

>>> Yeah, you would hope so, wouldn't you? Knackered the UN72 on the
>>> front of the tandem in very short order. The UN52 on the back, which
>>> gets more load, was still fine.
>>
>> That's probably more to do with differences with how it was fitted
>> or the bike/load than the model of BB.
>
> No, in this case it's because the particular BB was ****. I mentioned
> the bike/load thing (you can see it in the bit we've quoted) since it
> was relevant

Sorry I missed that bit.

- the BB with the higher load (the rear one) was a UN52
> and was still fine while the UN72 was dead. Both fitted at the same
> time. You'll have to take my word that they were both fitted
> properly. (actually the UN52 wasn't - it's a 73mm BB in a 68mm shell
> with a 68mm spacer/mount/whatever - but that's deliberate cos the LH
> and RH cranks are different makes).

OK, but in general with many cases, I suspect the tighter the BB is
fitted, the faster it wears out. There's often some binding with the cups
tightened with the "correct" torque.

~PB