I bought an IP-039 from velobuild/Peter 2 years ago this spring. I've been riding it ever since, I think I've put about 1500 miles on it since then.
Recently I've noticed that the 'braze on' derailleur hanger mount has not become flexible where it mounts to the frame. The derailleur would flop back and forth and hit the chainstay. As far as I could guess, the problem came primarily from the weak rivets used, not from frame flex.
Initially I thought that I wanted to drill out the existing rivets and use rivnuts instead. This quickly changed once I realized how much extra work that would be. I would need a new custom hanger, I would need to drill the frame etc. Instead I opted to use a slightly different kind of rivet to the ones that LTK (manufacturer of this frame) had used. The original rivets were 1/8 inch diameter (or probably the metric version of this) aluminum rivets. I decided to opt for stainless steel 'large flange' rivets. You can see the difference in the pictures with the two different rivets.
Now is where the fun starts. Once I get the rivets I realize that because of the curved construction of the hanger, the nose of the gun will not fit flush to the rivet head. It took a lot of thinking, and some drilled out rivets, but I figured out a solution (
http://www.eaavideo.org/video.aspx?v=1432781652 This is a very useful video too). I unscrewed the nose piece as far as it would go and used the curved derailleur bolt adapter to give me enough stand off room to use the rivet gun. Riveting is a little more challenging than I expected. You have to apply a significant amount of force to keep the nose on the rivet face and you have to squeeze the gun at the same time. My first couple of tries were terrible and I had to drill them out. Once I realized the adaptations that I needed, I was able to get good rivets in.
Total Cost:
Rivets- $6.50
Harbor Freight Riveter- $5.00
Here are some photos that detail the process:
