Ok, My pug frame has a 68mm BB shell, so i took the BB out of my road bike which is also 68mm thinking it would fit, but no joy, the cups on the road bike BB are to high, see pic, when i screw them in they hit a small lip in the shell on the frame where the threads end.
So which BB is needed. BTW the one on the right is the road bike BB.

Does the pug have British threads or french?
You may be on to a loser anyway.

If the cups screw in okay both side, you could always file down the obstacle inside the BB shell as long as you don't ruin the threads.

Is the small lip some left over braze or part of the BB lug?

It has English threads, it screws in no problem at all, up to a point, give me ten mins and i'll post a pic.

a) the spindle on the BB will probably be too long to get a decent chainline if the BB's for a road double. It'll work but might be noisy.

b) check out my thread 'Stronglight bottom bracket misery'. You might have a collar in the BB shell that is stopping it from screwing in all the way. I ended up getting a Miche Primato BB which has no flanges so it's more adjustable.

Ok i'll look into that cheers, here is a pic where you can see the lip just beyond the threads.

Ahhh, all is clear. It's one of those welded frame thingies with a smaller bore in the BB centre (Do I sound like I know what I'm talking about? It's all a act!)

You've got no chance with the long threaded cups.
Are the pug spindle and cups no good? If they are ok, just use them until you have a better idea what gearing you want.

I know calculating BB lengths is a nightmare, you want to try to get a good chainline without having the chainring touching the frame, but persevere with it, try what you've got and make adjustments. Ask your LBS, if they are any good they'll do some measurements for you.

BB spindle lengths seem to be shorter on more modern cranks than they used to be. I found a Sakae road double for cheap, put the 40t chainring on the outside, mated it with a 122mm BB (closest I could get to my calculated 118mm at the time) and found to my suprise that it was a perfect 42mm chainline.

Conversely I buyed me some new Sugino RD cranks and a 103mm BB to match - advertised as giving a 42mm chainline and found it was 44.5 whe fitted to my frame. WTF?

So calculations can only be approximate at best.

Hope this helps.

Well you certainly sound like you know what you are talking about to me, thanks for the info, appreciate it.

Forgot, i can't use the origional as the drive side cup was shot where someone had tried to remove it in the past, i had to grind a slot in the face of the cup and wack it loose with a chissle, shame as the rest of it wasn't bad.

Come to think of it, has any of the pug owners past or present changed their BB if so which did you use, this is slowing my build down at the moment, i'm not doing anything else until this is sorted.

You could cut the overlong cup down to fit (use the old cup as an exact size guide).

You could buy a threadless bottom bracket.

You could have the BB shell reamed out - extending the thread into the thicker shell part.

If the thicker shell part is separate (an insert) you could have that removed (it is probably brazed in there).

I had thought of this but was unsure if it would create a weak point in the frame, surly it's there for a reason, or maybe not........who knows, hmmmm

I would just cut the cup down to the old size then.

I'll nip to my lbs tomorrow and see what they say about threading further in, if not i'll have a look at cutting the cups down.

I have another question though, the stock BB spindle was 121mm with a double chain ring, obviously i'm now going to a single chain ring set of cranks (yet to purchase), does this mean i will need a BB with a shorter spindle, If so which width.

i recommend you buy a decent frame and an inexpensive BB, as opposed to the other way round. failing that, pot luck is the best.

How about a threadless BB.

threadless BB or cut/dremel a longer one. PTFE tape will give you a good snug fit.

I have read stories of them coming loose, i'd never seen one till this morning when my lbs suggested one, i can't see how they will come loose and he has assured me that it will be fine, i'm tempted to get one as it seems the simpler option, on the other hand is it cutting corners.

i had a carbolite and I just put one of these in .... and it was fine...

http://www.parker-international.co.u...4-f64225fd3e92

Did your frame have the lip mine has, (above pic)

sorry can't remember...:( I am useless....

Spindle length depends on make and model of cranks. There is no standard length.
If you are buying cranks, get them first and either:

• buy a BB to match,
• or, take cranks and frame to LBS - get them to measure up for you
• or, if the cranks are a well known make, search for the drivetrain database on here,
• or, put cranks on your existing BB and see how much out they are. If the chainline is out by 1mm, adjust spindle length by 2mm (as long as you have enough clearance from the frame for crank arms and chainring).

Well thats a pissa, i've just bought a threadless one ffs.

Can you remember what axle width you bought.

110

but you need to know your chainline... measure your rear whee bit...

Cheers, will check it out.

I'm having a hard time figuring this out, to me it's be like what came first, the chicken or the egg, i don't have my rear built up yet, so how do i know what width BB to get, if i do get the wheel built up then the chances are it will need redishing when i get the BB and cranks, or am i missing something, am i thick.

If it'll fit (shell depth), you need an english cupped miche primato.

If the cups are too long, you need something around a 107/109/111mm threadless, depending on what your rear spacing is (120 / 126 / 130). Or a dremel to reduce the depth of the cups.

See http://www.londonfgss.com/thread3372.html

When you mention spacing, this is the problem, i don't know where to start as my rear wheel is not built up yet, sooo how can i decide on a BB with no rear wheel and how can i set the rear wheel up with no BB or cranks or am i missing something.

Would these cranks fit on a Miche spindle
http://cgi.ebay.co.uk/Sugino-RD-Fixe...ayphotohosting
looking on the transmission thread people use Sugino-75 cranks with a Miche BB but the ones on ebay don't say what model the Sugino cranks are. HEEEEELLLLLP

yes they do, it says they are the RD model.

you need your rear hub, that will tell us what the chain line is, then you need cranks, then a BB that go together to match the chain line given by your hub/ frame combo. so you should build your wheels first if you are un-sure what your chain line will be.

now what kind of hub are you using? if it is a track/ ss freewheel then it will most likely be a 45mm chain line, then any combination of track cranks and the BB that fits them should suit. my sugino RD messengers (different to the ones in your link) needed a 103mm JIS bb to match the 45mm chainline of my phil wood hubs, i went with a phil wood 103mm jis bb, but the sugino 103 jis bb would have had the same effect on my chain.

spacing refers to the distance between the drop outs on your frame, they should be around 120-130mm. I think you are making this more complex then it needs to be. chain line seems like a dark art at first, but after you set up two or three bikes it starts to work out.

Well this particular bike is being set up with a sturmey archer 3 speed,reason, i will be using the 3 speed till i'm a little fitter and will be passed on to my missus (she's not wanting a SS/Fixed) i have another frame that i will be building up in the near future as a SS, at present i'm using this bike as a learning curve, does this change things.

measure the gap between the rear dropouts, it's hard for us to help without all the info, as you're finding out!

On my crappy calipers i,m getting 123.7 mm the paint is scraped off in parts of the inner faces of the dropouts and that's as accurate reading as i can get.