Steering tube?

[Goffins]

Is there a common size amongst manufacturers? Are Forks generally intercompatible without modification?

I can't really find any useful info online

The reason being, I have a Nirone 7 and want to replace the forks but I'm not sure of the bike head tube specs and there are no apparent markings.

 

[Randochap]

The Bianchi Narone 7 has a 1 1/8th" inch steerer, like most newer bikes.

You will want to consider the appropriate fork rake for the frame.

 

[PatrickPending]

most are 1 1/8" but you will still find 1" forks though rarer. I'd measure them just to be on the safe side

 

[Black Sheep]

you'll need to know both the diameter of your current fork, either an inch (normally with a quill stem) or inch and 1/8 which normally has a bolt on stem.

you'll also need to know how tall you need the steerer tube of the fork for an inch 1/8 system as it needs to come through the head tube and have space for the stem to bolt on including a couple of stackers if required.