Bicycles have rubber tires. Guess the greenies just have to walk...
Provided they walk barefooted for shoes are not made of grass either.
Also, bicycles are made of steel, steel manufacturing requires the uses of coal. Bicycles have saddles, these are made of either leather or polyurethane (oil derived). Same goes for handlebar grips.
They should also not eat because growing food of any sort requires stealing of land on which wild animals live.