I currently ride a 52/42 chainring set on my road bike. The crankset and front derailleur are old (ca. 1983) Suntour Superbe. I am thinking of replacing the 42 with a 39 (or lower), so that I can squeak out a higher cadence on the steeper climbs.
What are the limitations here? Can I comfortably go lower than 39 (say 38 or 37)? Provided I can get my hands on a chainring that fits the cranks, will the derailleur be able to handle it? I notice that there is a good 1.5 cm. of space (measured vertically) from the chain to the bottom of the derailleur cage.
Will such a combination (say, 52/39 or 52/37) make up-shifting or down-shifting problematic? (I know that 53/39 is a pretty standard combination these days, but thatís with newer equipment.)
By the way, the rear Mavic hubs are threaded (not cassette), so getting a new rear cluster is not really an option. I was lucky to find a threaded 14-24 (6 cogs). Apparently there is a 14-28 (7 cog) available, but I am not sure whether the 7 will fit.
As always, thanks in advance for any wisdom shared.