bottle dynamo
bicycle dynamo mounted in such a way that its friction wheel can be driven by the sidewall of the tire
en-GB/ˈbɒtl ˈdaɪnəˌməʊ/
en-US/ˈbɑtəl ˈdaɪnəˌmoʊ/
bicycle dynamo mounted in such a way that its friction wheel can be driven by the sidewall of the tire