Heya, about a year ago I got hold of a vintage cargo bike with the intent of fixing it up, modernising the important bits (Bottom bracket, brakes, that sort of thing) and riding it with my wife, However, when I got to the bottom bracket replacing I found that the width of the shell was 78mm, which is an odd one as my many hours of online trawling have told me, it was a cottered crankset before, and they were rusted on so bad I had to cut the crank arm and pin off to get them off the bike. My main question is, is there a bottom bracket out there that will fit this thing, as I'd love to get it up and running after taking a long break from the project!
To my knowledge its an "SCO Urania Long John Carrier" 1972, according to a webpage I found with photos of what appears to be an identical bike.
I don't have any pictures of the frame to hand and as I originally disassembled it over a year ago I'm struggling to find the other pieces of the bottom bracket, however if these will help a lot in the working out of a BB solution for the bike I can take some/rummage around harder to try to find the remaining pieces.
I appreciate any of your time you spend on this and/or all of the responses in advance thank you very much.

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Hello Yordaign and welcome to the forum

some of the small wheeled Raleigh models such as the Twenty (both folding and non-folding) & the Shopper series employ a shell of 76mm width

alas, it is 26TPI

if you could get one of the spindles you might be able to get the assembly to function with other cups

facing the shell on both sides would likely get it down into the vicinity of 77mm which should be enough for adequate lockring engagement...

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78mm = ~ 3”.

Klein press fit sealed bearing bottom brackets were also 3” wide. I don’t know how this bit of trivia will help your quest for a proper bottom bracket, but 3” width just sort of stood out in my mind as pretty much equivalent to 78mm.

Thank you both for your responses, and for the welcome! I appreciate the trivia and it was more than enough info to send me spiraling down a wonderful rabbit hole, learning about those bottom brackets, I love that sort of stuff, and I appreciate the info about the Raleigh spindle, I'm not sure if I'll be able to face off the frame, as I basically can't move it without a van, and I don't have a lbs at least that answers the question about getting a sealed cartridge square taperd bottom bracket, but hopefully I can still make a longer sspindle work!

One last question about that spindle though; is that the part that matters for overall compatibility? Or is there a possiblility that the cups won't fit with it? (In other words is it just spindle length that matters?)
Thanks again!

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Small suggestion: It might help to know what country you're located in.

I know when I moved from the USA to Sweden, certain I knew absolutely everything about absolutely everything, finding weird valve stems and crank puller threads that weren't even close in diameter to my often-used tool.

Many members here come from North American English speaking countries, but there are others with backgrounds and experience that might be helpful here.

I'm also wondering about the internal diameter of the bottom bracket shell.

Heya, I'm from the UK here

And when I measured the inner diameter it reads 35mm

Thanks~