42mm Inside Diameter Head Tube

[surveyorcam]

Hi Everyone.
New to the forum.
I have an older dual suspension mountain bike, a giant ATX900. It has a weird head tube inside diameter of 42mm, which puts it somewhere in between the old 1 1/4" standard and the 1 1/2" standard.
Anyone know what type of head set was intended for this diameter head tube?
Cheers
Cam

[cny-man]

You need a 1 1/8 headset. Google "head tube diameter" One helpful result: http://en.wikipedia.org/wiki/Head_tube. Also, just Google "42mm headset." http://www.ebay.com/sch/i.html?_kw=42mm+headset

[surveyorcam]

Thanks.

I've been able to figure out it is a now obsolete Microtech Integrated head set that never became standard.

It used a 1 1/8 steerer with bearings press fit directly into the frame.

The closest modern standard is a Zero Stack headset with 44mm head tube inside diameter.

So my options are ream the head tube out to 44mm or get a machine shop to make a custom reducer.

Anyone know anything about reaming? For example, how thin could I make the walls of the head tube before I weaken them so much that they fail?