Join Date: Jun 2004
Location: Northern Nevada
The snow and ice won't do the rack any good, and the ultraviolet will accelerate wear on the soft parts (straps, plastic stuff, whatever you have up there). Having said that, though, you have to replace that stuff every few years anyway and you might not notice any difference.
What I wonder, though, is why anyone would even THINK of leaving a rack on if you're not going to use it. I put mine on and take it off for every ride that requires transport (not many; I'm lucky to live in an area where I can do good rides from home). Installing or removing the rack takes less than five minutes (I can take it off in less than two). Leaving it on increases wind noise dramatically on the highway and cuts my gas mileage from around 32-34 to 27-29. Makes no sense to drive around with it on the car if I'm not going to use it until April.