Bottom Bracket Axle Length

[MacB]

Hi, doing up an old frame and tempted to replace the old style BB with a cartridge one, chainset is still useable.

Do I just get the same axle length as the old style has and how do I know which style of square taper it is?

 

[PpPete]

I would go same length & JIS.
Unless of course you are spreading the back triangle to take a modern wheel - in which case easiest (for future compatibility) is to go with Shimano standard....

 

[MacB]

Thanks Pete, I'm not sure what I'm going to do yet, it's an old steel MTB I picked up from the tip, just because I liked the handlebars. It has horizontal rear drops, OLD of 126mm and no derailler hanger, the derailler was mounted via the axle. It was a 6 speed triple but I've been musing on what to do, I gave away the friction thumb shifters it had on it.

Was thinking I might do a fixed/SS 69er(26" rear and 700c front) out of it, whack on a 1" threadless headset and Xcheck forks. but it's not a bike I intend keeping it's only to practice my mad mechanics skillz!!!! It really comes down to whether I'd make my money back, or at least not lose too much on the deal. At the moment I get:-

frame - free
forks, headset, spacers and stem - £100
Midge dirt drop bars, v-brake drop levers, v-brakes bar tape and BB - £80
wheelset inc tyres etc - £200
chainset, pedals, chain and cog - £60
saddle and seatpost - £40

So I'm looking at £500, I could probably get that down a bit to maybe £350 with patience.

 

[RecordAceFromNew]

It really comes down to whether I'd make my money back, or at least not lose too much on the deal. At the moment I get:-

frame - free
forks, headset, spacers and stem - £100
Midge dirt drop bars, v-brake drop levers, v-brakes bar tape and BB - £80
wheelset inc tyres etc - £200
chainset, pedals, chain and cog - £60
saddle and seatpost - £40

So I'm looking at £500, I could probably get that down a bit to maybe £350 with patience.

MacB if the costs of parts above are mostly for new parts, then I think the chance of your recouping £500 is not good. The reasons are:
1) Bikes usually sell for less than the sum of their parts, whether new or secondhand.
2) You will not recoup the costs of nearly new parts sold piecemeal.
3) You can easily pick up a high spec £1000+ bike of yesteryears for £350 today. I am sorry but while very interesting the rebuild if sold whole does not appear to have as much of a market in comparison.

But if on the other hand the part's are secondhand but high quality, then you probably will recoup your costs.

It will be a fun rebuild though either way!

 

[MacB]

Yeah I know, I think I'm set on doing the SS/Fixed conversion so it would need a new rear wheel no matter what. As it's 126mm spacing that shouldn't be too expensive, i reckon I can get one for about £50. The rest I can probably cobble together for a lot less. May just leave it with 26" wheels, whack on some v-brakes and levers I already have, new headset and BB I can get for about £30. All in I reckon I could have it up and running for about £150, depends on how successful I am messing about with cones and bearings etc. I was initially going to put new bearings in the BB as the axle isn't pitted but I can get a cartridge one for under £10. Let's see:-

keep f&f - free
BB, chainset, chain and cog - £50
headset - £15
rear wheel - £50
front wheel keep existing - free but may go for a complete wheelset deal
bars and stem - keep existing
brakes and levers use what I have - free
saddle, pedals, tyres, tubes and seatpost, use what I have - free
cabling - £10

So complete bike for an actual outlay of £125 maybe up to £175 allowing for full wheelset - reckon I could recoup most of that on a sale.

 

[RecordAceFromNew]

Yeah I know, I think I'm set on doing the SS/Fixed conversion so it would need a new rear wheel no matter what. As it's 126mm spacing that shouldn't be too expensive, i reckon I can get one for about £50. The rest I can probably cobble together for a lot less. May just leave it with 26" wheels, whack on some v-brakes and levers I already have, new headset and BB I can get for about £30. All in I reckon I could have it up and running for about £150, depends on how successful I am messing about with cones and bearings etc. I was initially going to put new bearings in the BB as the axle isn't pitted but I can get a cartridge one for under £10. Let's see:-

keep f&f - free
BB, chainset, chain and cog - £50
headset - £15
rear wheel - £50
front wheel keep existing - free but may go for a complete wheelset deal
bars and stem - keep existing
brakes and levers use what I have - free
saddle, pedals, tyres, tubes and seatpost, use what I have - free
cabling - £10

So complete bike for an actual outlay of £125 maybe up to £175 allowing for full wheelset - reckon I could recoup most of that on a sale.

One thing I have noticed, due to the mass migration to disc brakes and stans/tubeless, light quality used 26" rim-brake wheels are now going for a song (i.e. less than 1/3 of new prices). You just need to spread your dropouts by 9mm.

Why 700c front? If it was an mtb are you sure you can get your v brake to reach a 700c rim?

 

[MacB]

One thing I have noticed, due to the mass migration to disc brakes and stans/tubeless, light quality used 26" rim-brake wheels are now going for a song (i.e. less than 1/3 of new prices). You just need to spread your dropouts by 9mm.

Why 700c front? If it was an mtb are you sure you can get your v brake to reach a 700c rim?

would only be 700c front if I changed the forks, as it is I'll probably not do that so will stay as 26" front

 

[PpPete]

If going fixed/ss chances are you will need different length BB. If you have an old one that you can put on for now, sort the rest of the drive train out, then figure how much you want to add/subtract.

 

[RecordAceFromNew]

If going fixed/ss chances are you will need different length BB. If you have an old one that you can put on for now, sort the rest of the drive train out, then figure how much you want to add/subtract.

+1. Or it might be cheaper for you to use a bb you have already, and add/subtract spacers behind the rear cog, and/or move washers on the rear axle, to get the chainline right.

 

[MacB]

+1. Or it might be cheaper for you to use a bb you have already, and add/subtract spacers behind the rear cog, and/or move washers on the rear axle, to get the chainline right.

makes sense, I was planning on the ST55 Single chainset from Spa at £20 but I could put the existing back together and aim for a SS/fixed based around the middle ring of the triple.