I got my compact 20 inch tire electric folding Vilano Atom from Amazon ( http://amzn.to/2iahWu1 ). Its a relatively inexpensive electric bike with magnesium wheels and a 350 watt hub motor. Its original Shimano freewheel (14-30 teeth) was had a very large high gear which limited the maximum pedal speed. I upgraded it to a 11-32 teeth DNP freewheel (http://amzn.to/2uMNVq3) for a 25% increase in top speed. This electric bike can already accelerate to 24 mph with the electric assist to keep up with full size 26 inch bikes. You will need a Park Tool FRS 1.3 Freewheel tool to remove the old freewheel. Do not buy the DNP freewheel tool.. it doesnt always fit. I wasted 1 week after getting the tool only to realize it does not fit. See my video when i compare the two removers: https://youtu.be/VepywyXaxpA