When I stripped down the old steel Magistroni Senior headset on my Italian frame (dated 1958 - 1961) there was a 180 degree steel shim between the race and the headtube.

Dimensions are:

Fork Steerer OD 25.4 (1")
Magistroni Race OD 30.1
Headtube ID 30.2 - 30.4 (two measurements at 90 degrees)
Shim Thickness 0.37


I can see why the shim is needed.

But I am wondering what this says about the history of the bike.

Would this have been standard practice/ tolerences used by old builders. Was it usual to reem the headtube this much ? Was it usual to use a shim like this. Or is it just sloppy work ?

Is this a sign that the headset is not the original headset ?

Would be interested to hear if anyone has experience of this and opinions, thanks.