How Much Weight Should You Put on the Bar?

Some of you have, no doubt, been to gyms where they post the “prescribed” weight for a workout on the whiteboard. Others of you maybe remember long ago when I used to post weights alongside the workout. This leads us to three great questions: Why did I stop posting weights? Why do other gyms post weights? If there is no weight listed, how much should you do?
I stopped posting weights because some people would do the posted weights with atrocious form. Others would do the posted weights with passable form but take forever to finish, essentially getting a strength workout when I intended to give them a conditioning workout. And finally, a few folks would do the posted weights and it was too easy. The takeaway for me was: people need to find a weight that they can do with decent form, that allows them to get a conditioning workout, and that delivers a decent challenge for them.
Other gyms post weights because… no two CrossFit gyms need to be the same. One gym’s awesome culture is another gym’s nightmare culture.
As a general rule, if there are 21 or less reps of something in a workout, you should pick a weight that you can do unbroken (at least for the first round, if there is more than one round). This is a rule with MANY exceptions but it is a pretty good starting place. If you’re not sure what weight you should use, try asking the coach what the INTENT of the workout is. Is the intent to test your strength? Then go heavy. Is the intent to push your technique? Then pick a weight that you can maintain good technique with. Ask questions and discover the purpose behind the workout which will hopefully lead you to an appropriate weight.
As a final note, if you are not very competent with the movement, the weight you should use is A DIFFERENT MOVEMENT. Don’t do motions you don’t have at least a moderate technical grasp on during the conditioning section – you’ll just burn in crummy technique. Do something else. Ask your coach for a substitute movement.