Just picked up an old steel Colner frame. Don't know model or year.

Tried to put my Sugino bottom bracket in but it's too small.

The width of the frame where the bb goes in is 70mm, and internal diameter of bb hole is 35mm (my measurements may be 1mm off in either direction).

Anyone know what type of bb I need? Preferably with a product link so I can look at it.

1 Answer 1


Among bikes with threaded bottom brackets, the Birmingham Small Arms (aka English, British, BSA) is the most common one. This uses a shell that's 68mm wide, with an inside diameter of 33.9mm. The non-drive side is reverse threaded, so you screw the BB cup in anticlockwise on that side.

I'm not familiar with Colner, but one source describes it as a downmarket version of Colnago, which is an Italian brand. Many Italian bikes use Italian threading, which has a 35mm internal shell diameter and a 70mm wide shell. There are a number of other older thread standards, but it seems likely that you have an Italian threaded shell. The measurements, if you measured correctly, do correspond.

You will need to choose a spindle width that's appropriate for the cranks you are using. If you know that the Sugino you had is the correct spindle width, then you would simply search for that width but specify an Italian threaded bottom bracket. Phil Wood sells the BBs and cups separately, so that you can buy any length spindle and either BSA or Italian (or French or one of the less common ones) cups. However, most companies' cups are integrated with the BB. Italian threading is much less common than BSA, but because of Italy's prominence in the cycling world, I think chances are decent that you can find a correct BB. Phil Wood is likely to make a correct length spindle, but they are a premium brand - you could at least rest assured that it will be a durable BB if you get it.

I am assuming your intended crank uses a JIS taper, which is more common than the ISO taper used by Campagnolo cranks. You will need to match the taper type as well.

You could also consider going to a bike store and having them a) confirm the BB measurements and b) see what BB they can acquire. This is a vintage parts situation, so the younger mechanics may be less familiar with the situation, but it always helps to have the bike in front of you to confirm.

  • I believe you're right it does seem to be an Italian threaded shell after further research. Thanks for your very in depth reply! Ride safe 🤙
    – Jetzki
    Jan 8, 2023 at 21:43

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