I have a beautiful titanium frame made by Van Nicholas. Unfortunately it uses long reach rim brake calipers front and rear (branded Van Nicholas, but I would say tektro made). They are pretty ugly and I want to upgrade to Ultegra calipers. On the front I can change the fork for a short reach one, so all good, but on the rear the ultegra caliper would be too high and won't reach the braking surface on rim. Do you have any suggestion about mount adapters, caliper extensions I can use to adapt and lower the rear Ultegra caliper?
Thanks a lot for your help.