The whole thing I was told about bike stands from the Pro Senior MX racer I bought my CRF450 off of told me is that that little bit of sag creates some pressure in the shocks, and if you store the bike for longer periods of time with weight on the shock/forks, they will start to leak. Guess what? The YZ250F that I didn't keep on a stand started to leak after I left it sitting for 6 months on its triangle alone. The CRF is kept on a center stand almost all the time. The YZ now has a center stand and It still sits dormant in my garage and the forks haven't leaked since then.