Shimano Ultegra/600 downtube shifter issue.

Phew, that was a bit close…!

Just replying to confirm that those flat-backed bosses are what you need and that they go on top of the curved bosses that are fixed to the frame. You had to use these on most alloy frames back in the day, like Vitus 979s etc.
 
Just for the record, the backplate to carry Shimano indexed dt shifters come in 3 styles -
Flat, as used here to adapt these bolt in bosses
Steel curve, as removed from the steel frame in this thread
Alloy curve shallower, and would fit the frame, but might not be compatible with the inter-threaded bosses.

You often get glued-on bosses on early carbon road frames, and I've seen glued-on bosses on a few mid 90s alloy frames - expecially those with main tubes bonded into lugs.
 
When I fitted shifters to my titanium frame, the tube has an ovalised profile, so the probable fit best would have been the large radius ones, I didn't know you could get different fittings. I thought it's a remnant from history and you either fit what you have or buy something completely different and modern, so filed the edges off the curve and made them fit
 
Back
Top