Freezing headset cups to ease installation - does this actually work? Sometimes it can be a tight fit installing a headset cup / race. Bike forums are full of people saying putting the cup in the freezer helps installation based on their anecdotal, uncontrolled experiments. Internet forums are also full of people saying it doesn't help at all, or you need to use dry ice or something else.

Aside from everyone's personal anecdotes, or what someone on the internet said one time, is there any evidence that freezing headset cups makes them easier to install? Does freezing them really shrink them sufficiently to make a difference?
According to this link the thermal expansion of aluminum 6061 is 13 micro inches/(inch x °F).  A headset has a diameter of 1.125 inches, and circumference of 3.5325 inches.  Assuming you change the temperature of the headset from 70°F (room temperature) to 0°F (typical household freezer), you'll change the circumference by 13 x 70 x 3.5325 = 3215.5 micro inches.  Which is .0032 inches. The diameter will now be smaller by .001 inches.  I really don't think that will be enough to make a difference when installing a headset.  Hopefully somebody can check my math/science to ensure I'm applying the information correctly. 

Here's a nice chart illustrating the thermal expansion of aluminum from 0 K to 293 K (20°C).  This seems to fit with my numbers from above that shows a decrease of 40 degrees (+20°C to -20°c) results in a change in length somewhere in the vicinity of 1x10-3 length units.