Is a 20-inch folding bike good for commuting?

Yes, for mixed trips. The 20-inch wheels roll better over cracks and curbs than 16-inch wheels, and the fold lets you take it on trains and into offices. It is slower than a full-size bike over long distances.

Does the 7-speed gearing make a difference?

It does on hills and into headwinds, where a single-speed folder forces you to stand and push. On flat ground the extra gears mostly add weight and maintenance.

How does it compare with a 16-inch folding bike?

The 20-inch version rides more smoothly and feels more stable, but it folds into a larger, heavier package. A 16-inch folder is easier to carry onto crowded transit.

Are V-brakes enough on this bike?

V-brakes give strong stopping power in dry conditions and are easy to service. In rain they lose bite sooner than disc brakes, so allow more distance.

What should I check before buying a folding bike?

Check the folded dimensions against your storage space and car trunk, and confirm the frame hinge and latch feel solid. Also check the rider weight limit and whether the seat and handlebar heights fit you.