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I keep my bike in a utility room at home which doubles a larder, extra storage, a shed, a laundry room etc. etc... It's one of those rooms. But as a laundry room I have a dehumidifier which is running most of the time as there are a lot of people living in my house so there is often clothes drying.

I was wondering if the dehumidifier would dry out the oil on my chain? I try to clean, degrease and relube my chain regularly so I'm not particularly worried about this happening, more curious. But this then got me thinking, would it be of more risk to the areas that don't get treated as often, so lube around cables or deeper into the mechanics around bearings etc.?

Probably one of the stranger questions I've asked about a bike :)

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    The heat will slowly dry the lubricants (significant over periods of years, not months). The low humidity should not be a problem. And of all the lubes in the bike, conventional chain oil would be the least affected. Nov 15, 2016 at 12:57
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    If it did, there would be a layer of oil on top of the water it collects. Nov 15, 2016 at 14:33
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    I'm wondering: Do you mean dry as in does the oil evaporate faster or as in will it help evaporating the moisture (= water) that is on the chain under/in/on the oil? Nov 15, 2016 at 15:17
  • I'd be expecting your bike would last longer due to being stored dry, rather than put away wet after a damp ride, and staying wet.
    – Criggie
    Nov 16, 2016 at 9:20

1 Answer 1

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No. Here's a vague, handwavy descrption of why: A dehumidifier will reduce how much vapour (oil or water, so long as the boiling point and saturation vapour pressure at room temperatureare appropriate) is in the air. In the case of water, which is in plentiful supply, there's usually enough vapour in the air to affect the rate of evaporation, because there are plenty of sources, both natural and man-made. In the case of oils, the amount present in the air is so low that reducing it further will have no effect on the amount that can evaporate.

Where the dehumidifier might have an effect is that it blows out slightly warm air (assuing it's working fairly hard). The extra heat might just be enough to increase the rate of evaporation, but in practice I'd be surprised if the temperature of a bit of bike in the output flow of a dehumidifer could get 5°C above ambient -- much less than leaving it in the sun.

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  • It is set to laundry setting a lot in addition to using the central heating radiator in that room, but as you say, even with those conditions, I can see how that will hardly increase the rate of evaporation to any worrying level between relubing anyway. Thanks. Nov 15, 2016 at 11:41
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    To take another point of view at this argument: The evaporation rate of lubricants mainly depends on how much of it is already in the air. Apart from very odd locations, this is essentially nothing. So, if the dehumidifier were a problem for your bike, so would be storing it in most other locations.
    – Wrzlprmft
    Nov 15, 2016 at 21:18
  • Assuming that your lubricant does not contain water, it will not be not be affected by the lower partial pressure of water vapor. The question is: does the dehumidifier lower the partial pressure of the other ingredients. I would guess that the boiling point is so low at the partial pressures, they will not condense, but you'd have to check if you wanted to be sure. Temperature will play a larger role but relative to 0 Kelvin. en.wikipedia.org/wiki/…
    – David W
    Nov 15, 2016 at 22:41
  • @DavidW the assumption of no water was implicit, I only mentioned water to explain what the dehumidifier does.
    – Chris H
    Nov 16, 2016 at 6:57

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