The trailer wheel is normally the front wheel of one of my other bikes, it's got a dynamo in it which (on the other bike) powers the lights, when in the trailer it charges a cache battery which can then be used to power Garmin/phone/lights/etc when you get to where you are going.
The trailer wheel is normally the front wheel of one of my other bikes, it's got a dynamo in it which (on the other bike) powers the lights, when in the trailer it charges a cache battery which can then be used to power Garmin/phone/lights/etc when you get to where you are going.