When bookings are made via the online booking wizard (OBW) they automatically come into your system as 'Generic Bookings' meaning that they are allocated generic rather than specific bikes.

This means that you then have the flexibility of assigning a specific bike at a later stage - for example when the customer comes to pick up their bikes.

However this flexibility to allocate later also brings a bit of complexity for your users.  If you would rather have BRM automatically allocate a specific bike each time it gets a booking via the OBW, then you can use the 'auto-allocate' setting:

System -> Settings -> Online

When this setting is ticked BRM will choose the first available specific asset that belongs to the generic asset in question, and allocate it.

Please note default is AUTO-ALLOCATE ON