If you want to book multiple items at once then simply select your bikes before doing the create.

First of all, make sure you're in create mode

  1. choose your bikes
    1. either by ID
    2. or by category
  2. select which bikes you want
  3. drag the dates you want (for one of your bikes) in the planner
  4. add your customer name (or select from the Client Ticket panel above)
  5. It will create a booking with all selected Items

This little diagram shows you the steps:

Please note -

if you choose bikes by ID then they are auto-selected

if you select via category you need to select them one at a time by clicking on them.