Originally Posted by
fietsbob
I saw one* that sits over the front wheel , friction drum drives the tire, so lifting it off the vtire would mean only its weight remains .
*was in the folding bike posts... mechanism type, , already used in Velosolex Mopeds. there a 2 stroke motor gives the energy..
The eventually "coming" Shareroller lifts and has zero drag. Also, add-e and go-e friction drives.