Bar ends are perfect for folding bikes. They have three main uses.

Firstly, they provide different hand positions to keep your hands fresh, and minimizing hand injuries. Secondly they provide extra leverage on the outside of the handlebar, this makes turning easier and more efficient. This is extremely important on a commuter and folding bike Lastly, they allow the rider to climb hills easier by pulling back on the bar ends. This creates more friction, by digging the rear wheel deeper into the pavement. This means more force from your legs will help propel the bike. Obviously this is huge, since everyone needs help climbing hills.