Originally Posted by MrFlamey

When testing bikes, I found the 20" wheels on the Tern Verge X10 (which I bought) were quite reasonable, but the 16" wheels on a Brompton were a touch too small. However, small wheels are quite nice for riding around town, and as linberl says, twitchy really feels responsive in the right setting. Larger wheels are just a lot better for handling rougher terrain, and even just pot holes in the road. I've hit a couple of huge pot holes while riding at night on my Verge, and although I didn't come off, it did not feel good. Having said that I've also tried riding down a mountain on it (following the trail, I'm not totally insane) and it was surprisingly managable since I was able to see what I was doing and was careful. Still, I am really looking forward to riding something with larger wheels again.