Bottom bracket - loads of Issues

[young Ed]

Check a bike retailers website.

Measure the length of the old axel and that of the BB shell on the frames. Road bikes are usually 68mm, MTBs 73mm shells. The next measurement is the axel length.

Also you may need to be careful if the crankset is French or Italian as they tend to be ISO square tapers, whilst Shimano and others are JIS

so for example 70X113 is a 70mm internal diameter BB shell and axle length of 113mm?
Cheers Ed

 

[fossyant]

Re measure as it's either 68 or 73.

 

[young Ed]

Re measure as it's either 68 or 73.

not measured it yet but just throwing that one up as 70 is listed on chain reaction link form @smokeysmoo above and you hadn't mentioned it
Cheers Ed

 

[smokeysmoo]

not measured it yet but just throwing that one up as 70 is listed on chain reaction link form @smokeysmoo above and you hadn't mentioned it
Cheers Ed

Only Italian threaded BB's are 70.

British ones are all 68 or 73.

 

[Rickshaw Phil]

so for example 70X113 is a 70mm internal diameter BB shell and axle length of 113mm?
Cheers Ed

Not internal diameter but the width of the shell - measured from one side of the bike to the other. I'd hazard a guess at it being 68mm on your bike.

I'm curious what the bearing surfaces on the inside of the cups are like. Also, the surfaces on the axle. If they aren't badly worn or showing signs of pitting it may be possible to replace the balls, regrease and rebuild. Bottom brackets often take 1/4 inch balls the same as rear hub bearings.

 

[young Ed]

Not internal diameter but the width of the shell - measured from one side of the bike to the other. I'd hazard a guess at it being 68mm on your bike.

I'm curious what the bearing surfaces on the inside of the cups are like. Also, the surfaces on the axle. If they aren't badly worn or showing signs of pitting it may be possible to replace the balls, regrease and rebuild. Bottom brackets often take 1/4 inch balls the same as rear hub bearings.

ultimately replacing with un55 is best though
shall measure with vernier callipers as a real digital figure is always going to be more accurate then any ones guess!
Cheers Ed

 

[Rickshaw Phil]

ultimately replacing with un55 is best though
shall measure with vernier callipers as a real digital figure is always going to be more accurate then any ones guess!
Cheers Ed

Oh, yes. a UN55 should many thousands of miles. T'was just a thought if you wanted to experiment and gain some knowledge.

I shall ignore the other comment and put it down to youthful cheek.

 

[I like Skol]

Ed. Throw away your old B/B cups. Even without looking at them I can assure you they are Fubar'd. For the bearing cage to get into that state the axle, bearings and cups have been grinding away like mad and the cups bearing surface will be gouged and any new bearings fitted will not run well or for any length of time.

Save up the few pennies for a UN55 (even the UN26 will run better than the bits you are planning to fit and last far longer).

UN55 starts at around £13 delivered depending on size and supplier.

 

[young Ed]

Oh, yes. a UN55 should many thousands of miles. T'was just a thought if you wanted to experiment and gain some knowledge.

I shall ignore the other comment and put it down to youthful cheek.

t'is great being this age every one puts plain rude down as young! nah sorry no offence meant but surely measuring is better than guessing?

Ed. Throw away your old B/B cups. Even without looking at them I can assure you they are Fubar'd. For the bearing cage to get into that state the axle, bearings and cups have been grinding away like mad and the cups bearing surface will be gouged and any new bearings fitted will not run well or for any length of time.

Save up the few pennies for a UN55 (even the UN26 will run better than the bits you are planning to fit and last far longer).

UN55 starts at around £13 delivered depending on size and supplier.

will spend the 20 quid odd on a possibly parktool shimano un fit tool and then the monies for the actual un55
will do the same for my other baby when she needs it or when i need something to do and have 15 quid going spare, ie probably never!
Cheers Ed

 

[Rickshaw Phil]

t'is great being this age every one puts plain rude down as young! nah sorry no offence meant but surely measuring is better than guessing?

Yes, do measure it as you'll need to know which size you need. My intention was to say that 68mm is so common that it is more likely to be that out of the two. The BB shell probably won't be made to such fine tolerances that it'll be dead on 68 or 73.

 

[young Ed]

Yes, do measure it as you'll need to know which size you need. My intention was to say that 68mm is so common that it is more likely to be that out of the two. The BB shell probably won't be made to such fine tolerances that it'll be dead on 68 or 73.

ah cheers!
any levels of bad inaccurate engineering couldn't get more then about 1/10th of a mm either side of intended size!
Cheers Ed

 

[Rickshaw Phil]

ah cheers!
any levels of bad inaccurate engineering couldn't get more then about 1/10th of a mm either side of intended size!
Cheers Ed

Let us know what you find when you've measured it.

 

[young Ed]

Let us know what you find when you've measured it.

come tomorrow bed time now!
Cheers Ed

 

[fossyant]

Stick a cartridge BB in. Just not worth the messing. £15 and all sorted.