What bottom bracket do i need

Hey,

I have a old frame, with a unsealed bottom bracket that needs replacing... i think.. the cranks are wobbly from left to right.. i attach a pic.

I have no idea what bottom bracket i need..

any help greatly appreciated

Cheers

Charlie

What frame is it? What cranks are they?

You'll need to know what width your BB shell is, how long your axle is and what taper you're using...

I got mine out with a screw driver and hammer. Fine if you dont ever want to use them again.
It took 2 hours though and my knuckles were covered in blood afterwards :)

erm i have NO idea what frame it is its old..... it has some old cranks too... ill take a pic one sec,

I dont have any of the tools to get the thing out so maybe fitting one myself is not the best idea.

Does anyone on here run a workshop that would be able to give me a hand for a few english coins?

Thanks for the replys!

Take the crank arms off and see if there's anything marked on the BB - it may (if you're lucky) have some info on it we could help you decipher.

Is the play in the attachement of the crank arm to the axle or the axle itself?

the axle, both the cranks wobble at the same time. new bb yeah?

It might just need adjusting.

Go to your local bike shop and if they're nice sorts they'll tell you what's happening with your BB and then maybe someone on here will help you out...

cool, will do.

If anyone is around soho and fancys helping out im around weekdays 9.30-6!

Cheers guys

shell length = measure the length of the frame at that point, it'll be 68mm or less likely, 72mm
thread type = english, italian or french (or other weird thread type) best worked out by taking the thing to an LBS
axle length = measure it, you'll need a bit of cardboard, and two knives and some imagination. works for me :)

might just need rebuilding/ adjusting, you'll need a BB tool for the job, theres loads of different ones, so unless you have the right one, its a bike shop job anyway. you could be ghetto and use mole grips to undo one cup, extract all the balls and axle, clean, inspect, if not pitted/ collapsed/ disintegrated balls then ressemble with decent thick grease and mole grip that sucker back up*

*warning, you are highly likely to ovalise the cups doing this, but in cases of extreme student poverty it will work well enough. remember to get the lockring back on good and tight, otherwise it'll be loose and fucked within minutes of riding.

The crank isn't that oldfashioned as it's cotterless. So that means it's most likely ISO (English) or Italian. From the outside, dead easy to tell if you accurately measure the shell (frame part the BB sits in). Italian is 70mm, ISO is 68mm or 73mm.

If ISO the left hand side will be left hand threaded. If Italian, both sides will be standard right hand threaded.

Highly unlikely to be any other type as they are all too old. If you want more info, read Sheldon:
http://www.sheldonbrown.com/gloss_bo-z.html

BTW if you're still stuck next week and can make it to South Ken during the day I'll help you take it off. I have the tools.

To the great wise old men of the forum,

I have bought a new Pro-Lite Trentino Frame from CRC. I cannot find any data on the frame but in a very unhelpful way, they have told me its English 68mm. I have tried English 68mm BB and the damn thing binds after about half a turn.

Please can someone tell me if this is *actually *an English 68mm or if its something else. I am wondering if maybe the thread has little bits in it or something from the manufacturing process and English 68mm or if its simply that CRC doesnt know what the feck the frame that they sell is.

And

Shot in the dark if someone can tell me the chainline as well.

Have the bottom bracket threads been chased?

CB shortly after reading that;

I presume when you say that you mean the equivalent of cleaning the thread?

No, i have done no such thing... How would i go about doing that on my own?

(You make me laff Mr AndyP)

Chasing the bottom bracket threads is common practise on a new frame to ensure the thread is clean and evenly cut. It sounds like your BB needs it, hence the one you're trying to install stopping after half a turn. You can do it yourself (and here's a video showing you how - Facing /Chasing the Threads on the Bottom Bracket - Video) but it's probably best to get a decent bike shop to do it for you.

Shot in the dark if someone can tell me the chainline as well.

The chainline depends completely on the rear hub. Track standard is 42 mm but there are quite a few variations so check the transmission database thread on here. Once you know what hubs you are using you can work out the rest.

Hi all!

I have similiar problem. I have old road frame with 120mm rear fork. I want attach to it a wheel with miche primato hub, so the chainline will be at 42mm. Also i have sakae gxc cranks, shell length is 68mm(italian). Which axle length should i choose? 107 or 110mm?

Either should be fine, you'll have a variance of 1.5 mm which is barely noticeable.