Bike Stuff weird GT Avalanche 3.0 mount

I have been cycling into Glasgow to work rather a lot recently. Well, I say alot, but by that I mean two days a week. but that's better than the no days a week when I spent all my time filling out application forms.
Dennis (my bike) has not disappointed. He's quite fab.
I added a carrier as rucksacks are just not comfortable.
The one I got was the Top Peak something or other with the slider for locating into their very expensive bags. It was the disc brake version which basically means it's a bit bandy and has drilled square section welded on to offset the mount from the fram so as not to foul on the brake mechanism. Now, if anyone has a GT Avalanche, they will know about the weird rings in the frame, see picture below.



These have an internal diameter of about 11 mm and are about 22 mm deep. So, how to mount? I made a couple of T type flanges from an old aluminium towing eye. I gave the sections 14 mm and 10.5 mm diameters with the section that would sit in the ring being 10 mm deep. These were then tapped to an M5 thread. The peg on the rack was filed down to allow it to sit in the ring to about 11 - 12 mm.

He's looking good but I've changed the tyres to Continental Double Fighter IIs as these have a smooth center which is better for road use.
Scary thing is, on using them, my journey time was 10 mins less than usual. This could have been the following wind, but...
In the meantime, Whilst down near the Bells Bridge I saw this excellent graffiti.