49685d02_nt_Convention___iusmentis_com___Basis_in_priority_document
[Claim] A bicycle comprising the lamp of claim 1, said lamp being powered by a dynamo. [Benefit of priority?] No. Although lamp and bicycle are mentioned, the dynamo is not. A "power source" can mean a lot of things (e.g. a battery) and so "dynamo" cannot be derived directly from the application. [Basis in priority document] 
"This lamp can be used in vehicles such as bicycles. Of course this requires a power source in or on the vehicle."
Priority under the European Patent Convention (EPC) (in Patents > European Patent Convention @ iusmentis.com)
Basis in priority document