Syntaxsid

How to corner on a narrow u turn efficiently?

Machka 

Keep your inside pedal up.

Colnago Mixte

Practice a lot. I like doing tight figure 8's for balance. I don't worry about where the pedals are, it's impossible for them to scrape while doing this, at least on any of my bikes. You should be able to do a u-turn inside the width of a narrow traffic lane (~6-7 feet).

Stay relaxed and don't turn too sharp or the front wheel will "scrub".

BloomBikeShop

Look where you want to go. Your body (and bike) will follow suit.

Start slow and increase speed as you increase confidence. It is also very helpful if you can find someone and watch them do it.

And never stop practicing!

Colnago Mixte

Confidence is key. If you panic during the middle of a sharp turn, nothing good can happen. Stay relaxed, as any hint of tension, hesitation, or uncertainty in your body will manifest itself in bad cornering lines, and lost traction.

wphamilton

Go to a parking lot, and practice doing figure-eights using the lines to guide you. After a couple of minutes you'll start making them tighter, with more confidence. I ride 5K to 7K miles per year and I still do this sometimes. Even just a minute or two is helpful.

Flip Flop Rider

break pretty hard going into the turn while you're still going straight, I mean you're doing a u turn so speed is not a concern/factor. Slow way down then turn and burn

rubiksoval

Get your body weight back and to the outside of the saddle. Slow earlier, let off the brakes, then hit the turn. Flatten the turn out as much as possible by going from outside, apex, outside. Pull your bike up level as soon as possible to begin pedaling.

bruce19

Exactly what we used to teach in MSF courses. It works.