My mountain bike is dirty from dust, mud and oil. Does it do any harm to the parts if I leave it dirty for a few more months - and for the sake of background information - or forever? I can imagine the granulate part of sand doing harm to the transmission (3x9 Deore XT), however that already happens if the mud splashes on it during the ride and the effect should wear off after some kilometers.

I'm interested on the effect of the varnish of the frame as well as dust entering into rotating parts (usually all embedded in an axle bearing) or the suspension fork. In order to remove oil film I need to use a degreasing product which might do more harm to those parts than the dirt remaining on it. Cleaning techniques involving pressured water might increase this effect.

Having clean tires is probably a good advise for security reasons/grip, but the combination of profile and my tracks causes them to become clean pretty much automatically.

The ideas should apply to other bike types as well.

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    Be cautious if using a pressure washer, and if you do be sure to open everything up afterwards, dry it out and re-grease everything afterwards. Pressure washers can blow the grease that may have saved it out of bearings and seals, as well as blow more dirt into small spacers.
    – Nate W
    May 9, 2018 at 23:23
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    @NateW Caution is appropriate but cyclocross racers and pro road race mechanics use pressure washers on bikes all the time. As long as you don't point the spray directly at bearings and so on, it doesn't seem to cause any actual problems. May 10, 2018 at 11:19
  • David Richerby that is a valid point, as long as you know where not to direct the spray it should be fine.
    – Nate W
    May 10, 2018 at 15:03

2 Answers 2


The main concern is water, and any other substance that might promote corrosion, such as road salt.

Leaving mud or dirt on the frame provides material for water to soak into. Even if you let it dry out it would held water for longer than it would take to evaporate otherwise, and can soak up more water later.

You obviously want to get grit and dirt off of your chain and sprockets as it sticks to the lubricant and promotes wear.

Bearings do have seals, so if you are careful with degreaser there should not be a problem getting it into bearings and affecting the grease or other lubricant.


As brought up in comments there are areas that are more prone to damage through corrosion than others. Fork stanchions in particular.

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    Fork stanchions and rear shock are the biggest issue I see. Have a look at an old BSO - the drive chain will invariably still work (to some degree), but the forks are usually rusted up. Better quality bikes have lesser of a problem, but pitted forks stanchions are an expensive to repair. (I might let the bike go unwashed a week or two, but will always clean the fork and shock.
    – mattnz
    May 9, 2018 at 20:17
  • Anything that is not corrosion-resistant will rust faster. Brake springs is one usual suspect, as do random non-load bearing bolts.
    – Criggie
    May 10, 2018 at 0:06

A bicycle, like any other means of transportation, needs maintenance. When riding a bicycle, dust and dirt, abrasive particles that can damage your bicycle permanently, if not removed in time. And simply, it is much more pleasant to ride a clean bicycle than on a dirty one. If you are allowed funds, you can buy specialized tools for cleaning the bike. The main condition for the manufacture of these cleaners is to minimize their impact on the paint and coating of the parts. The best of these cleaners are harmless to the environment and completely biodegradable by microorganisms. In addition to detergent water and solvents, rags, shoe brushes (perfectly clean the knitting needles and chains) and even toothbrushes (they are very convenient for cleaning hard-to-reach places and chains) are also useful. Experiment, try different methods and in due course you will have to leave for a minimum of time to clean the bicycle.

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