mslulu2

I have 3 nice old mountain bikes with years of accumulated sludge, grease, dirt, etc. / can i safely steam clean them or power wash the components while they are still on the bike?

repechage

I would not go that route. Even motorcycles are best not washed that way.

RobbieTunes

Never thought I'd see that question here, but I'd say no.

I agree with repechage. There is just too much that can go awry.

It would be a lot easier to disassemble them, clean, and re-assemble.
In that way, you'll uncover and discover things that need to be done.

Bianchigirll 

I am not sure I would go with steam cleaning but I often go to the carwash with a big bottle of Simple Green and an old bottle brush or two and scub up "new to me" bikes.

busdriver1959

The heat from steam cleaning might not be too friendly to the paint. Power washing WILL push water into all of the bearings. Neither technique will clean the bike better that Simple Green and elbow grease.

StanSeven

You will do lots of harm to bearings by filling everything with moisture and take out all the grease. The headet, bottom bracket, hubs, and pedals probably will need overhaul by the time you finish.

dddd

A little spray cleaner or WD40 and a suitable arsenal of brushes will accomplish what I think you're faced with.

A pressure washer might be ok if there were no cartridge "sealed" bearings AND you were going to rebuild the bearing assemblies later, before rust set in.

I've used external methods for flushing out water-contaminated bearings, but it can be an oily mess. It dissolves out the grease so will need more-frequent maintenance afterward.
Any seals may or may not let water in, but with no way for the water to get out. A gear hub or a bb cartridge would likely be ruined.

The cheapest bikes are the "best" candidate for this kind of treatment. The cheapest derailers, for example, don't have the really closed-in spring barrels that would trap water, and no bearing seals either.

Cables don't like water either, but your bikes might already have contaminated housings where some oiling to displace any water can't do any further harm.

lostarchitect 

My vote on this is that you CAN do it, but as 1 part of a total rebuild. If you're going to replenish the bearing and grease, I don't see why it's so bad. If you want to do this just as a shortcut to cleaning the bike, don't.

RFC

BS. Strip, steam clean, lubricate.

randyjawa 

Steam will soften sticker glue, causing them to loose adhesion. Power washers will drive water into bearing cavities and, believe it or not, actually remove paint, not to mention art work.

Stay away from both power washing and steam cleaning of vintage bicycles! I speak from experience on both issues.

RobbieTunes

I worked from the premise that he did not want to strip the bike.

photogravity

That would be my assumption too. If stripping the bike an if you are not concerned with damaging the graphics, go for it. Other than that, I'd not go that route.