Usually means that you will need to go in full kit...bike shorts, jersey, gloves, shoes. Make sure to bring your pedals if the bike has none. You will probably mount the bike on a trainer and they may adjust seat height, handlebar height and angles as they go along. They may hang plumb lines from your knees to make sure you are in the correct position. Expect to ride the bike on the trainer with people looking closely at you. Final step may be to watch you actually ride the bike on the road in the drops, hoods and while climbing.