Replacing Bottom Bracket

Matt.K

I've decided to bring my old hybrid out of retirement for days when there's a risk of ice.
It's at least 10 years old, and has never been properly serviced (my father-in-law gave it to me when I was at uni, so it's had lots of abuse).

Anyway, I went to take the bottom bracket out last night and inside was a scary sight.
It's a old-style cup and bearings job. One of the bearings was completely collapsed and starting it's way up the seatpost tube! The other one was missing a couple of balls and the rest fell out when I removed it. :shock:

My first thoughts are to simply replace the bearings (£1 from Halfords) and re-assemble the rest.
But then I'd really prefer a sealed cartridge BB.

So my question to you knowledgeable folk is....

Is it possibly to replace cup & ball BB's with a cartridge one?
I've not measured the diameter yet, but the width of the frame at the bottom bracket is just under 70mm.
Would this work with a 68mm bracket?

Thanks,
Matt

desweller

I have done exactly this. You want a Shimano UN54 bottom bracket. Cheap and capable. You will need to know your axle length and width of your BB shell. You may also need to get the tool to tighten the cup.

biondino

Umm, the balls are supposed to fall out when it's taken apart, so you can replace them, and there are always fewer balls than would fit if you packed them in tightly!

the_hundredth_idiot

DesWeller wrote:

I have done exactly this. You want a Shimano UN54 bottom bracket. Cheap and capable. You will need to know your axle length and width of your BB shell. You may also need to get the tool to tighten the cup.

+1 Less maintenance/tweaking required in the future as well.

Chain Reaction Cycles have a really good deal on the UN54 at the moment - most sizes are only £12. I've bought one for an old Marin Pine Mountain which I'm renovating and which also had an old cup and cone BB on it. Probably cheaper to replace with a UN54 than renovate the old BB once you have to buy specialist tools for the old BB (e.g. lock ring spanner, pin spanner) plus new bearings).

Just measure your old BB spindle for the axle length and the width of your BB shell - CRC have lots of sizes in stock. Sounds like a 68mm BB shell - if it looks a smidgen wider than 68mm then perhaps it's just paint overspray or something? The other common size (I think) is 73mm.

The adjustable cup of the old BB should come out nice and easy (sounds like you've already done that). The fixed cup could be a real bee-yatch as they are in really tight. My dad helped me with mine - using Sheldon Brown's home made tool and a length of scaffolding pipe. Next time, I'd find someone with a bench vice or ask my LBS for some help.

Matt.K

Mmmm, it's tempting.

I've got the whole thing off and stripped.
The fixed cup came of fairly easy with a large adjustable spanner. Sounds like I've been lucky there!

The decision is probably going to be financially biased towards a new set of bearings as they only cost about £2 and a new cartridge BB is going to cost at least £10.

This is, after all, a very budget refurb with the aim of a pub bike / commuter when temps drop to near zero.

Thanks for all the advice

Wooliferkins

The UN54 will last much longer than new races

elcani

Get the UN-54. Much better option than renovating the old BB.

lae

The problem with cup-and-cone BBs is that you have to service them regularly. The problem with that is that you have to take the crank arms off reguarly. And the problem with that is, if you take the crank arms off regularly, the square taper hole enlarges with repeated tightening and your cranks get stuffed. Plus taking cranks off regularly increases the chance that you'll mess up the threads that the removal tool screws on to, then you have to either cut through the BB spindle or use a balljoint splitter to remove the cranks (which will probably bend them).

I also have a UN54 in my 70s Raleigh daily bike, and it's been perfect.

Matt.K

OK, so I measured the axle last night, it's 136mm from end to end! :shock:

The largest cartridge bottom bracket I've seen is about 120mm.

Am I measuring this correctly?
The bottom bracket shell is 69mm wide, so I'm assuming 68mm + paint.

salsarider79

The axles lengths go up to 127.5mm, can't see how yours would be over 130mm.
Are you measuring with bolts? Best bet is to take it to your Local Bike Shop, get them to fit the correct part.
p.s. A sealed BB will last for a lot longer than the cup/cone BB you had before. It may cost more to fit, but will work out much cheaper in the long run.

will3

Matt.K wrote:

OK, so I measured the axle last night, it's 136mm from end to end! :shock:

The largest cartridge bottom bracket I've seen is about 120mm.

Am I measuring this correctly?
The bottom bracket shell is 69mm wide, so I'm assuming 68mm + paint.

It is a cotterless crank, right (ie square taper)?

Matt.K

Yep, square taper cotterless axle, meaured end to end without nuts.

I couldnt believe it myself when I put the callipers up to it and they just kept on going right up to 136mm!

I think I'll probably end up taking it to the LBS for a bit of advice.

lae

York Cycle Centre on Hull Road are pretty good.

That said, they did tell my girlfriend that they were unable to re-fit the back mudguard on her bike after the bolt came loose and fell out... :?

They've been great for everything else I've done though. They removed a truly well-seized cup-and-cone BB and knocked out the headset cups of my Coventry Eagle restoration for free.

Matt.K

Do you mean York Cycleworks?
I was going to head to either there or Cycle Heaven in Bishopthorpe Road then I can book my Flyer in for a service at the same time.

wgwarburton

Matt.K wrote:

Yep, square taper cotterless axle, meaured end to end without nuts.
.

Nuts? Hmm- if your BB axle has protruding threaded ends and nuts, instead of bolts that go into a threaded hole, then you need to be measuring from the ends of the tapered parts, not the ends of the threaded parts...
If that's not the case, just ignore me.... I'm probably going nuts myself...

Cheers,
W.

Matt.K

OK, due to the general disbelief at my massive axle here's some pics of it:






I've decided to just get some more bearings for it for now and see how it goes. If eventually I want to replace it with a cartridge then I'll cross that bridge when I come to it!

sheffsimon

I would think 127mm axle will be fine, cranks will just be closer together, which is better.

Bit of adjustment to front changer, job done

stickman

A few years ago I had to replace a cartridge BB that was 136mm, may have been Sachs? Fitted a 127mm, crank/rear stay clearance was still ok luckily.