It really depends on how you use your pressure washer. If you do like the instructions say and keep the nozzle the distance they tell you to keep from the surface being cleaned, then you should be okay. But if you point it down at the BB, axels or cogs on the rear and get real close with it to get every last spec of gunk off in places the eyes normally won't see anyhow, then you might be a candidate for not using the pressure washer.
I'd just wipe it off with some of those pre moistened towelettes that come in a big plastic canister. Or maybe spay it with a hose. But if for some reason the pressure washer was hooked up and ready to go, I might would use it. But since it's normally not hooked up, I'd not bother for that little bit of splatter that is mostly cosmetic and just offends your visuals.