himespau 

I'm going to be replacing my crankset with a new (to me) one I got off ebay. It's occurred to me that I haven't done anything to service my bb in the 3+ years (I don't ride a ton so only 1500 miles or so) that I've had the bike and, given the dirty gummy state of the chain when I bought it, I'm not sure the previous owner did anything to it either. So that'd imply that, in the 15 or so years this bike's been around, nothing's been done to it and when I'm pulling the crank anyway, this might be the perfect time.

Currently, the bike has a cup and cone bb with a rather non-standard size (if bikepedia is to be believed) of 68x120 mm. When I bought my crankset, the seller threw in a cartridge type bb (Shimano UN-54) that he said was 68x118 (or maybe 115, but he was pretty sure it was 118). My calipers are at work at the moment, so I haven't gotten around to checking either measurement.

Given I've never serviced or replaced a bb before, if I want to do something to mine, the way I see it, I have 2 options. Buy a bb wrench and pin spanner for the current setup and some new bearings (15 years of abuse, why not drop a few bucks on new bearings) and use the current bb. Or I could pay an lbs to remove my current bb (why buy tools for a one off thing?) and either put in the cartridge bb I have if it's the right size or buy a new one and a tool to remove it.

The first option seems overall cheaper to me ($25-30 for the two tools, a few bucks for some bearings and I've got a bunch of grease), but is that the better option? Would I be better off in the long run going with a cartridge bb? Or should I just leave the bb the hell alone as it doesn't seem to be causing me any real problems, it's just a convenient time to service it and I haven't done that before?

Oh and yes, my current bb and the cartridge are both JIS square taper, so that's not an issue.

FBinNY 

You can't know for sure until you field strip and examine the existing BB. If the cups and spindle are in good shape, then it's only am matter of new balls an pennies worth of grease and you're good to go. But if either of the cups or the spindle are worn to where there's pitting or gouging of the ball track, then it's replacement time.

You have to choose between the convenience and ease of a cartridge system, or the serviceability of another cup/come system. My bias is to the user serviceability, but many others disagree. I suspect the key factor is how well and quickly you can install and adjust a cup/spindle BB. But it's your call.

As for the cost of the tools, it gets tricky. Obviously a single splined cup tool for a cartridge BB is less expansive than the three spanners needed for a cup/spindle BB, but you still have to buy or borrow the tools for your BB to know where you stand.

himespau 

3 spanners? I'm only seeing 2 for cup/spindle, but then I'm probably missing something. Fixed cup removal?

FBinNY 

Yes, the third wrench is for the fixed cup. I have seen some sets that do it with 2 wrenches, having the fixed cup tool on the other end of the pin spanner, but many don't. You don't need the fixed cup tool to examine and service the BB, but you will if you want to change to a cartridge.

wrk101

My favorite bb tools for vintage bikes are the Sugino branded ones. Then you only need two tools. Unfortunately, they are out of production, and have gotten pricey. I see one set on ebay right now, $90 bin......

+1 To below, have a shop pull it for you, and install the cartridge unit instead.

FBinNY 

I think I have a few, if anybody's interested. Brand new, unused, for $35.00 including shipping within the USA.

fietsbob

Fixed cup removal /and a 15mm open end is 1 wrench
lock ring hook spanner is a 2nd tool ,
and the pin spanner for the adjustable cup are a 3rd.

OTOH by going to a common Shimano UN-?? cartridge bb
there is just a single spline installation tool..
If you are not interested in doing maintenance of the loose ball BB
no reason to invest in the tools ,
just get a shop to fit the cartridge BB and be done with it.

FastJake

+1

If you decide to use the cartridge BB no need to buy all the tools, especially if you never end up using them again.

I too prefer loose ball BBs simply for the serviceability. Something about not being able to fix a cartridge unit bugs me. Once it's shot, it gets thrown out and needs a whole new unit. I know they last quite a while, but still...

himespau 

you know, a mechanic's time around here is ~$75/hour (not that he sees all that). If they charge me a half hour's time to pull the bb and install a cassette, it's about breaking even to buy the tools even if just to check.

Since I'm putting a road crankset on an old rigid mountain bike (it currently has a biopace touring crankset on it, so I'm confident it can handle the extra two teeth the road crankset has given it can fit the oval of the biopace), I'd like to preserve the spindle length if possible to keep the chainline the same, so I'll probably at least give the current loose bb setup a try (something the guy I got the cartridge bb from made it sound like it might be more a 115 mm, so I might have to buy a new cartridge one anyway).

Kimmo

+1 serviceability.

Inbuilt obsolescence sucks balls.

himespau 

As far as a fixed cup tool, can I just use the Sheldon Brown bolt method? That looks pretty workable to me. I guess, I don't know if it works in reverse though to finish tightly screwing a cup back in.

mikezs

It should be self tightening, but just making the bolts really tight and then (un)screwing it back in with a bit of loctite should be enough?

CACycling

Keeping the spindle length the same won't necessarily kep the chainline the same. Spindle length is mostly determined by the crankset, not the frame.