What alloy Ti? I've done a cold-set on a 6/4 frame and had to bend out the rear-triangle by more than 6" on each side before the adjustment would stick. Takes A LOT of force to move it that much; I couldn't do it by hand. I had built a special table to clamp the frame down and used a hydraulic auto-jack to bend one side at a time. I was sweating bricks that I might snap the rear-end (it was a customer's bike too). Personally, I would just bend out the dropouts with my thumbs each time I wanted to insert a 135mm rear wheel.