An explosion of color. Giant ATX 800 from '99

[Obi-Juan]

These have 44mm steerer tubes right? So these can take a ZS44/30 top and EC44/40 lower for a tapered fork.
Dont know if thats what youre trying to do, that kind of restomod, but thats what i think of first with frames like these and old cannondales.

Well, the head set had some reducers
The external measurement is 43.4 mm. Since it does not come under pressure because it has some clearance, I imagine that the internal measurement of the head tube will be 44 mm.
The idea of putting a tapered fork is interesting
I'm always thinking about building a Cannondale, but I'm pretty unfamiliar with the brand and I'm a little scared of working on one.

The headset is an FSA Orbit Extreme because its outer diameter coincided with that of the head tube and was very aesthetic, really in the Cannondale style with the flush head set.