I have a 7701 Dura Ace double crank. It's a 52 outer - 39 inner ring. What is the smallest tooth count inner chainring that I can bolt on? I plan on doing a lot of climbing this - next year. I combined 2 cassettes and now have a 13-28 cassette and it works great with my Dura Ace rear derailleur. I just want to have a bail-out setup just in case I need it.
Thanks in advance for any assistance or input!!!