Is it just me or do bearings rust very easily? 
What can I do to prevent/fix rust damage?
Thanks
The best thing is to prevent rust. Prevent rust by keeping your unicycle dry.
are your bearings sealed??
Bearings are pretty cheap (on most unicycles), and they are something that can and should be replaced every 1-2 years of hard use. Don’t really worry about it. If you concern yourself too much with rusting then you won’t go out and ride in the rain, or you will spend too much time drying off the uni. Unicycles don’t have very many parts you need to worry about rusting, and the parts that do rust are so easily replaceable.
My bearings also have rusted, and have been used for around 1 year of hard use so mybe I’ll replace them soon.
uhh… do they still spin? do they make noise? do you ride long distances?
you know where i’m going with this, i hope, i would just smear a bunch of grease in/on them and keep riding… its not like the bearings have to spin at 10000 rpm… i’ve NEVER replaced bearings, and all of mine are fine… i don’t grease or oil them often or even look at them often at all…
if the rust is extensive, as in you can peel flakes of it off, replace, otherwise, i say penetrating oil, spin a bunch, grease, and keep riding.
Don’t use a pressure washer
You can easily blast past the rubber seals, and blow the grease out of the bearing, with a pressure washer. A light spray with a garden hose is fine. Then ignore the bearings. Spraying them with wd40 will soften the grease, don’t do that. Ignore them until they don’t turn smoothly, then replace them.
They don’t call them “maintenance free” , because they need maintenance. Ignore them till they turn rough, then install new ones.
ride them after they are rough! save your $8!
I agree with Scrobro
Motorcycle mechanics are super fussy about bearing smoothness. Sucks to be stuck way out there, and a bearing can go bad fast at 150 MPH. Unless you are jumping farther than Scrobro, his uni “ride em till they are really broke” maintenance schedule should be fine.
Believe it or not, motorcycle and uni bearings are sometimes identical. IMHO, the side bangs on the cranks, and the pressure washer hitting the exposed rubber seals, is why the identical bearings may go 50,000 miles inside a motorcycle hub, carrying 300 lbs at 65 MPH, yet the same bearing sometimes fails in a 12 lb uni going 4 MPH in less than 1000 miles. The bearings aren’t designed to take side loads. This is why they say if you pull them off, they should be replaced. The puller puts enough side load on the bearing to make flat spots.