Frame

I'm planning to adapt a factory Pre-Unit rigid rear section to the Duplex front loop on my '61 T110. Ideally I would have just started with an early 50's but sometimes you can't be that picky when the right project opportunity comes along. I'm told aftermarket Unit hardtails (like the David Birds, FMW, Elswick's, etc.) bolt right up to a Duplex frame but I really want this one to look like a stock early 50's bike. The factory rigid rears are starting to get a little scarce, especially those that haven't been butchered almost beyond use. I feel a little better that I was able to find one that has already been cut, probably with the intention of doing exactly what I am hoping to do.



Here is a side-by-side photo with my friend's Pre-Unit rear section that has stock lower tubes.



I'm not the first to do this (no one is ever the first to do something with bikes this age). The following it a Duplex Pre-Unit that has had an early rigid rear modified to fit.



The spacing where the rear section bolts to the frame is wider on the Pre-Unit than the Duplex/Unit mount. I'm thinking I could just machine two 11/16" spacers to compensate. Obviously the lower mounts are going to be a little more involved. I'm hoping not to have to tear the whole bike down to the frame to mock it up. I'm thinking I might be able to use a Unit front loop for mockup.