A participant not following cues is not a big deal unless a) they are being inappropriately vocal about their opinion b) they are doing something unsafe and contra-indicated. If someone walks in that late, get off your bike, see if this is their first time, or let them know what type of class this is, tell them to warm up before jumping in, etc... Don't talk to them from your bike it will just embarass them and make you look bad. you will look a lot more professional if you just speak to her for a couple of seconds one on one while the rest of the class is doing their thing.

if she leaves after that short a time, see if you can find her and find out why? was something hurting? explain to her what spinning is if she is unfamiliar. sometimes its tough, but it is better to be diplomatic right off the bat. it throws them off

my two cents

Han