Eplore the Simple Logistics Of It
I'm guessing that your co-workers have a hard time imagining the daily routine
that's needed to make bike commuting work for themselves.
Maybe a slide with at 48 hour timeline that shows when you prepare/plan, when you lay out clothes, what/when you pack, the riding time, the prep time at work, the work day, the prep for return, the return trip, the unpacking/prep for the next day, etc.
Would this be helpful?
Also, how about a few photographs in the briefing that show typical set-ups for handlebars/lights/odometer or rear rack/bags/lights.
Don't forget to talk about safety measures as well - not to start any debates here, but bring in your own experience and perspectives.
Good luck. When is this thing?