[quote=“ranlee, post:324, topic:67878, full:true”]
Switching crank sets that are different sizes isn’t like switching your wheels.
You don’t just decide the night before, 53/39 tomorrow and 50/34 the following day. Unless you just have money to burn on new chain sets every weekend. Different sizes crank sets means different length of your chain. With 53 and 39 “teeth”, you’ll need a much longer chain than a crank with 50 and 34…“teeth”. Which means, on top of a new crank set, you need a brand new chain. Also, you can’t get a 53/39 crank set at Sora or Tiagra (group set) level.[/quote]
That’s not necessarily the case, in my experience.
I have switched cranksets between 53/39 (with a 12/25), 52/36 (with 12/27) and 50/34 (with 12/29) without changing the chain. It probably is slightly too long (I really should check), but I just don’t use the extremes (e.g. 34:12, 34:13 or 50:29, 50:27) so it’s not an issue. Just remember to adjust the front mech.