100 is usually considered a good cadence. 120 when you're really pushing it is ok but if you're just going easy with 120 you should probably move up a gear.
100 is about right on a geared bike. My computer doesn't measure RPM's but I know what's about right for me.
climbing, cruzing and TT you want to be 90-110.
Sprinting over 130rpm.
The hour record is set at around 105rpm.
Team pursuit around 110rpm.
Epic rides around 90rpm.
Thank you sir ;)
You're riding with *%$?#heads if they tell you to shift to ride at a lower cadence ;-(
If they're telling you in a nice way and giving you the reasons why...that's a bit better ;-)