If anyone knows or has a set of forks to hand, what is the internal diameter of the upper part of a tapered steerer tube? I’m just being lazy and don’t want to have to take off a stem cap and fiddle about! I think it’s 22mm.

My old Pike is almost 23mm.

It’s going to vary make to make, and by material also…

As above. The outside will be constant but the inner will vary for different forks

If you can hold on I will try and measure a selection in the Garage later…

A steel 1in steerer used to have an inside diameter of 7/8in or 22.2mm
Steel 1 1/8in steerers used to have an inside diameter of 1in, or 25.4mm.

Aluminium steerers are sometimes thicker though.

Should have said this is for a set of Rebas. Looking at the smallest diameter really rather than being an exact fit. I’ve a little project in mind!

If by any chance you are asking with the view to fitting one of those BBB steerer extenders, then in my experience, the answer is that it will be too small for the 28.6-25.4 one and too large for the 25-4-22.2 one. FML.

No it’s not a steerer extender – I’ve a fork cork and looking at making a tube (probably out of 22mm plastic waste pipe) to hold tools and spares in there. Somewhere around 23-25mm would be fine as I could use a bit of inner tube as “expander”.