Hi Rex
I have just had a wheel built by a local bike shop, who is pretty knowledgeable but didn't have the specific info for Triumph wheels. I couldn't find a dimension in my manuals so I did some asking around of other wheel builders and was told by one specialist in Victoria 'put it in the middle', so thats what the local guy did.
Later [as bloody usual...] I found reference to the wheel building specs, but all they refer to is the measurement being from 'hub' to 'rim' - 27mm for WM2, 22.2mm for WM3.
I don't know if they mean from the outer face of the spline or the face near the spokes on the drive side, and don't know if they mean from the outer face of the bearing retainer [which drives the speedo drive] or the face near the spokes again. There is no illustration to show which.
I have measured 34mm from the spline face to the rim and 18 from the outside of the speedo drive/bearing retainer - the average of this is close to the 27mm figure so that seems likeley to be the way to measure it and means my wheel is now off-centre - aaarrrgggh!
Any info would be a help.
Also , how wide is a WM2 rim? The code has been polished off mine.
cheers
Phil