英文關鍵字
planetary
hub
belt
drive
bicycle
rotating
carbon
transmission
rotation
gear
rear
cogwheel
wheel
chain
inverted
bike
mechanism
white
fibre
transmit
background
pedal
gearbox
spin
pinion
workshop
gearwheel
turning
back
power
rotor
vehicle
growing
modern
bicycling
fixing
indoors
tyre
transportation
technology
engine
mtb
offroad
metal
change
reinforced