Originally Posted by
Dunbar
Unless you can spot the difference between a standard and compact crank I don't think you can do accurate mental calculations. The reason I leave my compact on the big ring most of the time is purely functional. The small ring is pretty much "spun out" at about 18-20mph which is precisely where road cyclists spend a lot of time (at or above.) I can't believe riding around on the small-small (or second to last cog) is good for the drivetrain either. The big ring on a compact is completely usable down to about 14mph IME and that's staying off the bottom three cogs to avoid cross-chaining. And lastly, who wants to constantly be shifting the front rings if it can be avoided?
A standard crank is going to be different since the 39T small ring is usable up to a higher speed.
Yes, that discussion was aimed at standard 53/39 cranks.