Suitable replacement for a Shimano UN71 BB?

Kell · Sep 14, 2015

Managed to get the BB out of my old P7 yesterday.

It runs really smoothly, but it's now 20 years old at least, and I want to replace it now while the frame's stripped down.

What are people replacing these with?

From a quick Google, it seems like a lot of people are replacing them with second hand UN71s - but the danger there is that I might end up with one that's worse than mine.

Would prefer Shimano as I've got the tools to refit it.

TIA

cce · Sep 14, 2015

UN55 is still available new in lots of places. It's a good BB.

Kell · Sep 14, 2015

Complete mechanical numpty question here...

Where do I take measurements from to ensure I order the correct part?

FluffyChicken · Sep 14, 2015

Re:

Take bottom bracket out

It should say shell and size on it.
Length may be a cide MM107 .. DH-L.. stamped on the axle to to side of the cups.

But measure the frame shell width
Measure the length of the axle too

Or post frame and crank details.

Kell · Sep 14, 2015

I couldn't see any figures on it other than the model number.

It came out (eventually) of a 94/95 Orange P7.

Cranks are Shimano something or others.

They don't say whether or not they're LX, XT, XTR etc. But I think as the rest of the equipment was XT or higher, then they're probably XT.

Pictures attached.

Kell · Sep 14, 2015

I'll have a look under all the crud to see if I can find any other markings.

FluffyChicken · Sep 14, 2015

Re:

It will need a 122.5mm, shell width is probably 68 as it is a P7 frame. It may say on the fixed cup black bit. I can't link the the axle marking as on the phone but check fixed cup side (drive side) in the crud between taper and cup, but on the axle. Like stamp marks.

Either way that is a nice M735 DeoreXT chainset hence the 122.5 axle length.

Kell · Sep 14, 2015

That's brilliant.

I will check it for any markings, but that's good to know.

Also, just done a quick search for the measurements you mentioned. Does that mean it's an English thread? and therefore everything tightens clockwise?

cce · Sep 14, 2015

Kell":1z7lvheq said:
That's brilliant.

I will check it for any markings, but that's good to know.

Also, just done a quick search for the measurements you mentioned. Does that mean it's an English thread? and therefore everything tightens clockwise?

an English thread BB is left-hand threaded on the drive side

Kell · Sep 15, 2015

Re:

D'oh.

Didn't check this thread before measuring.

Length of axle is 122.5.

But I measured the diameter of the shell not the length. Numpty.

There was a code though. Looked more like DNL than DHL to me though.

Suitable replacement for a Shimano UN71 BB?

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