Try not to mothball your bike for the Winter, or it just won't get used! Spray the insides of the frame tubes with WD40 or ACF 50 next time you are doing any maintenance. Put a very light film on any exposed steel work in late Autumn, keep the chain nice and oily and just take the bike out for a ride any time you can during the dry days in Winter (the more the better) . In no time at all Spring will arrive and your bike will still be in good shape for riding. This has worked for me for many, many years and many bikes, and I've never suffered from corrosion, even with the ones that had to be parked outside.