Other winter preparation involves repacking all the bearings ... with very lightweight winter grease, and removing all lubricant from the freewheel mechanism (even the lightest oil will keep the ratchet pawls from engaging at 20 degrees below zero or colder).
What do you do with the suspension at 20 below? I can't picture an elastomer squishing or oil flowing. Or is it all in the tires?

I can't imagine biking at 20 below; my knees don't like to bike when it's colder than 40 above! Brr!

-jk