Since the thread has been hijacked anyway (I am guilty as charged) thought I would add another 2 cents.
If you have the option, take off the rear brake entirely. Learn to stop using your front brake only. If you are in an emergency situation and you are used to using your back brake THAT is the brake you are going to hit....unload the rear end...swap ends/lay it down and crash.
If you get used to only using your front brake you will still have 90% of your stopping power even if you forget to apply the rear brake at all. If you insist, keep your rear brake operational but get used to using your front brake FIRST then applying your rear brake after it is unloaded (and when you lock the rear brake [like you will]-you will know that it is the REAR that is locked, not the front (which is a hell of a lot more difficult).
The one-in-a-million shot when a rear brake only is required (flat tire, very low speed high angle turn) usually gives you enough time to CHOOSE the rear brake.
BTW, (I am ready for the flames) laying it down is an admission of defeat and acceptance that you are going to be at least painfully injured. All most nobody, even in a car with anti-lock brakes uses available stopping power. Man up and learn to use your front brake. Burning your skin off while sliding down the highway rather then having a brake drum or rotor turn kinetic energy to heat seems a very very bad trade.
And to those with a one-in-a-million stories about laying-it-down-saved my life...I don't want to here it. Its like those "I got thrown clear in a traffic accident" stories used to justify not wearing seat belts. Cycling is dangerous...you do what you can to keep the odds within reason...not being able to stop is NOT going to improve the odds in you remaining alive and un-maimed.