Cleaning a bike with high pressure water is relatively tame and only mildly morally wrong if you really do not know what you are doing.
A lot more fun can be had with a diesel powered steam cleaner where the water-cleaning-solution-mix comes out at a toasty 150 degrees centigrade and the 'wand' has to be held with both hands due to the 'recoil'.
Pass the 'wand' over the three main tubes of a bicycle and you can sometimes pull off the stickers in one smooth motion. Stick a 1980's Peugeot racing bike in the way of the 'wand' and you can get down to bare steel. (Temperature dial has to be adjusted for Peugeot and Halfords own-brand bikes).
Put the bike upside down and well supported so it does not get instantly blown over by the onslaught of water and point the 'wand' at the wheels, in next to no time they spin at a very fast rate and every speck of grease and grime gets to be washed away. A quick point at the hubs and they are in as-new appearance. The same goes for the chain, even the most encrusted chain gets to be denuded of all lubricants in seconds. Handlebar tape - same again, back to as new except for cuts and holes.
Most of the bikes I washed so environmentally-unfriendily were customer repairs or part-exchanges to be sold on as second hand bikes. A thorough inspection was given afterwards and areas needing oil/GT85 were treated accordingly. The oily-rag was used for the Allen-key bolts and other steel nuts where the chrome surface was likely to be damaged. A quick polish and the appearance was so much better than achievable by other means.
I did test-ride many of the bikes 'abused' by industrial cleaning methods and we also had customer feedback. On one or two occasions I did inadvertently get water into the bottom bracket or freewheel, this was not the problem though, it was dirt forced in that was the problem. I learned through trial and error not to assault such areas and to give the Peugeot models an easier time due to that water-soluble-paint problem they had. Not once did we ever get a customer complaint, people were always very pleased with getting their bikes back looking as good as new.
Would I put my own bike under the 'wand' of the steam cleaner? Most definitely, even my retro-Campagnolo road bike (that has no sealed bearings). The 150 degree water would heat the frame/components so that on a summer's day it would be dry in a matter of minutes with not a speck of dirt left behind. The air + water + steel combination needed for rust to bloom was therefore kept to the absolute minimum of time. My bikes did not rust prematurely or have mystery rattles from the freehub or bottom bracket area. As a consequence of having cleaned the bike so quickly and thoroughly I was able to spend more time re-lubing my bike than I might have had otherwise.
Had I only have had a bucket of soapy water and hose to clean my bike with I doubt I would have done such a good job, however, that is all I have now to clean my bike with. I use clothes washing powder for the soapy water and give the bearing areas a very wide berth. Same with the hose, I don't point it at the hubs or bottom bracket. I find that riding the bike is a good way to dry it off, plus sticking it under that unshielded nuclear fusion reactor that passes overhead 93 million miles away on most days.
The fact of the matter is that anything you use to wash your bike with can push dirt into the bearings. But using water under pressure is not necessarily worse than using the sort of baby's toothbrush that archaeologists use to clean up a Sumerian tablet. The reason being that a jet of water will take the path of least resistance. That isn't necessarily straight into the bearings for there is a rubber seal in the way.
From a manufacturer's perspective with parts that come back under warranty, you obviously do not want to encourage 'idiots with steam cleaners' or to recommend any type of pressure washing. However, from my practical experience with hundreds of bicycles I know that pressure washing is best done all the way with 150 degrees hot water and that in some cases you can inadvertently wash the grease out of bearings. The risk is definitely worth taking, even on your own bike.
P.S. I do take my bike to the local car wash these days and let the guys there clean up my bike. I don't know what chemical they use in their bucket of soapy water but it seems to work wonders on my alloy wheels. Last time I had to force them to take my money, the time before they wanted all of £2. If you have a garage nearby and have a sense of adventure/humour I recommend giving the car-wash guys a go.
