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I jet washed my bike around 6 months ago and decided to do it again having got it caked in crap! Only for a mate to tell me how daft I was. Will this have damaged my Carrera Vengeance (I know it’s only cheap) but I’m 15 and I worked hard for it so I would hate for me to have caused permanent damage. Have any of you mountain bike gods out there got any advice for me? Thanks.

  • That question sounds like it's about something completely different, but the answers cover pressure-washing, too. – David Richerby Mar 9 '18 at 21:06
  • The damage that can potentially be done is not permanent no, so you should be fine, what it can do is wash the lubrication and grease out of things such as the bottom bracket etc. Just make sure you lube it up real good and if the crank start squeaking either service it or have it serviced if you don't have the know how – Nate W Mar 9 '18 at 22:37
  • Its controversial, watch youtube.com/watch?v=LzbpHGyFzc8 – mattnz Mar 11 '18 at 4:18
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If you aim the high-pressure water jet at sensitive parts like bearings (BB, wheels, suspension, headset...) the water will get inside, and your bearings will rust and die. High-pressure water jets are also pretty good at filling your cable hoses with water, and getting past the seals on suspensions. So when using high pressure to clean a bike, stay clear of the sensitive bits, keep the nozzle like 2 feet away so it gets mist.

However if you only aim it at the frame and chain, then no problem. High pressure is really good at getting the muck out of a chain, chainring, and cassette, but it also gets the grease out, so everything needs to be lubed afterwards. Just don't aim it up close to anything that contains a ball bearing or a seal.

As a side note, if you don't want stuff to rust... Your chain and cogs are made of steel because steel is very strong and cheap. Stainless steel is weaker, a stainless chain wouldn't last. Steel rusts though, but it needs to be in contact with oxygen to rust. The oil on your chain forms a film which protects it from oxygen (and rusting). After a good MTB ride, your chain and transmission will be full of crap and if you rode in mud, the water will have removed some of the oil. So if you can't clean your bike straight away, a quick spray of oil will protect the transmission against rust. No need to overdo it, just a little bit of oil is enough. When you clean it, this also removes the oil, so spray a little bit of it.

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  • Thank you very much, so no particularly lasting damage if I don’t do it again and lube my chain up properly? By the way I did go crazy and hit every part of the bike relatively close up with the jet. – Harvey-m Mar 10 '18 at 0:19
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    That would not be my takeaway. More likely your bearings contain water and will corrode. Your best option is to open all bearings that are accessible and to clean and re-lubricate them. – Christian Lindig Mar 10 '18 at 8:02
  • yeah if you "went crazy up close with the jet" your bearings could be in trouble... – bobflux Mar 10 '18 at 11:48
  • HP jets are also known to damage rubber and other soft or organic material. Therefore keep the jet away from the tyres, but also from the saddle if it is made from natural leather. – Carel Mar 10 '18 at 21:03
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Here's some key things to note:

  • Rubber bushings (from suspension components)
  • Rubber seals (From suspension components, SOME hubs, cassettes, cable housing, etc)
  • Sensitive metal areas (Shock absorber rams, wheel hubs, bottom brackets, headsets, derailleurs, etc)
  • Lubricated areas (Hubs, bottom brackets, derailleurs, shifters, chains, etc)
  • Fragile areas (Derailleur springs, shifter springs, etc)

All of these areas are VERY sensitive to high pressure/stress. If you point the pressure washer jet of water perpendicular to these areas, very close and hold it there for a substantial amount of time without moving it constantly, you could potentially do some damage. The best bet is to entirely avoid these areas. Hubs, headsets and bottom brackets contain grease, which the water will blast out of these areas and sit next to the bearings, causing them to rust. Springs inside derailleurs (mostly rear) and on your shifters are usually quite fragile with high pressure water, and these are also commonly covered in a grease.

Any soft materials like seats, rubber/plastic bushings for suspension parts and rubber seals can be cut with a water jet, depending on pressure, proximity to these parts and how long they're held in front of the pressure for. My pressure washer, when I was testing it on an old scrap bike, can cut through the fabric and sponge on my old seat. Having gone horizontal, I could have cut a sheet of seat off my bike if I wanted to. If you have an old, cracked leather seat on your bike, the pressure will destroy it in no time.

Anything that needs to move smoothly and freely, like cabling, will not appreciate the water either. If the water sits on any gear/brake cables for a prolonged period, the water will promote rust in these areas, causing the cables to first become hard to move, stretch and then seize entirely. If you have hydraulic brakes, you need to take even more care; Normal water in a hydraulic braking system is a big, big no-no. Seals on both the caliper and lever end can get severely damaged, causing fluid to leak or water to get in. Not only will it make the braking spongy if it damages it, it 'could' start failing altogether after heavy braking, heating up the caliper.

If you keep the water jet away from the parts mentioned above and try not to focus in one place, you should be okay. As a rule of thumb, keep the jet one to two feet away from the bike, aim at about a 45 degree angle and keep the jet constantly moving. Also, if it's an adjustable jet, set the jet to the fan setting, rather than the pencil-jet setting. Remember to lubricate the chain after, as well as drying the bike down by hand using an old but clean and dry towel that's absorbent. Don't use your best bath towel, use one that you're about to throw out.

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