48T, 49T and 50T x 26T doubles were quite common on French touring bikes prior to the 1970's. They used long cage Huret derailleurs, usually with a maximum 13-24T or 13-26T freewheels. The later literature say 36T to 53T but Frank Berto says different in "The Dancing Chain"

The biggest problem with a gap that large is the chain dragging on the inside of the large chainring when on the small ring and outer freewheel sprockets. Long chainstays and adjusted chainline helps reduce or eliminate the problem.

26T-46T



I stopped using TA 26T chainrings after I ovalized a few over the years starting from a dead stop on a steep grade. I switched to 28T or 30T chainrings and haven't had the problem on my TA rigs anymore.

50T-46T-30T half step triple. Same problem with chainring drag but on the middle ring with a 26T. 30T fixed it.



verktyg