jyl

It is winter in Portland, so temps typically 30-40 F with occasional excursions to 20 F and 50 F, and usually raining or threatening to rain.

My commute bike lives in the unheated garage. At work, I can lock it in the parking garage by the attendants at basically ambient temp, or in the card-access bike room at about 60-65 F.

In theory, is it better for the bike to stay cold all the time, or to alternate between 60 F and 30 F? Or does it not make even a theoretical difference?

I was thinking about moisture in the frame, at the bearing seals, etc.

FBinNY 

I don't think your temperature differences are enough to worry about either way, though if it's a choice between a warm low humidity place, and a cold damp garage the warm place is better. Often bikes kept damp full time rust faster, and the aluminum can darken or develop what look like white mildew (it's not) looking oxidation damage.

Bikes that face larger temp swings, especially if the warm place is more humid are prone to damage via water condensation inside the frame. This was and is a common problem for year round riders of high quality steel bikes, and why products like Frame Saver are sold.

If you have a garden shed, or a friend who has one, take a look at the metal tools stored there, and see how they're doing.

vanttila

+1. Just do your best to keep the bike dry.

Looigi

Agree. My theory/experience is it's way better to let it warm up and dry off spending most of it's time in the less humid environment. I have a hose rigged up so if it's really salty and gritty from the winter roads I can quickly rinse it off with warm water before bringing it in even if it's below freezing.

HillRider

I do the same with my "rain bike", a steel frame Surly Pacer. It spends it's off-time in a non-heated attached garage which does get cold but not really below freezing even in sub-zero outdoor temperatures which is why I'm such a fan of Frame Saver/ Amsoil HDMP.

cyccommute 

Granted my winters are drier than yours are but in 30+ years of commuting, I've never had a problem going from an unheated garage to a heated building at work to an unheated garage. All of my bikes now are aluminum or titanium so frame corrosion isn't a problem but even back when I was riding steel, I did the same thing without issue.

If you are getting moisture contamination in the bearings than your seals aren't sealing. Get better seals.

koolerb

My thinking on this has been to leave the winter riders in my dry garage. In the northeast the air is generally pretty dry in the winter time. The air in the house is warmer and more humid. Anytime I bring some thing cold in from outside it sweats a little. For a daily winter rider, in and out of the house one or more times a day, I'd worry about moisture collecting in the tubing.

fietsbob

Humidity from Warm, inside .. will condense when taken out. on places like inside a frame..

HillRider

That's correct only if you have a humidifier installed in your house. Unhumidified cold outside air has a much lower relative humidity when warmed up inside.

cyccommute 

Yup. Basic chemistry. And the reason that we can almost power our houses here in Colorado during the winter time on static electric discharges alone Air that has a <10% relative humidity at 20F will have a relative humidity of 2% at 70F. That makes it so that I zap the poor cat's ears every time I touch him

Edit: D'oh! I can be such an idiot at times! That's also why bring the bike inside from the cold won't cause condensation in the frame unless inside is humidified. The humidity would go down when you move from cold to warm.

FBinNY 

The problem of condensation/rust isn't about when you wam a bicycle, it's what happens when you cool it.

While the relative humidity drops as the air in a closed chamber is warmed, the absolute humidity is constant. Water vapor doesn't magically disappear when you bring a bike indoors. By the same token relative humidity rises in the frame as the air is cooled, and it can cause condensation the same way it does in your windows.

So simple rule --- if your windows are foggy or frosted, expect condensation and possibly rust issues if you bring your bike from that room to the cold outdoors.

I don't remember ever seeing a condensation problem producing enough water to settle to the BB and damage the bearings, but internal rust in steel frames ridden in the cold is a common, well documented phenomenon.

Of course it isn't universal, and I wouldn't expect it in dry climates, no matter how cold it gets. But here in the northeast and in Europe, we get cold damp winters and frames rusting from the inside out isn't rare at all.

HillRider

Which, as I said above, is why I'm a big fan of Frame Saver or it's work-alike products. Between internal condensation and tramp water getting inside from road spray, rain, etc. I see no reason not to protect the internals of a steel frame.

koolerb

I'd disagree. A house full of people breathing, taking showers, cooking, etc. I'd bet humidity inside is higher than out.

MikeWMass

but when you bring the cold bike inside, it will condense the humidity of the warm inside air. If you don't believe it, keep your sunglasses on when you come in from a cold day.

vanttila

Yeah, cuz the frame is cold. But there isn't a lotta air on the inside of the frame with moisture to condense, and as soon as the frame warms up, the water evaporates in the low relative humidity.

FBinNY 

You have this totally backwards.

Yes, when you bring it inside, you'll get condensation on the outside. But the outside is painted and designed to handle weather. Also as the frame comes up to ambient temperature.

Now, let's see what happens when you bring the frame back out. The humidity inside the frame will condense on the tubing as it drops below the dew point. That's the real problem since the inside isn't painted.

Sixty Fiver

My winter bikes stay cold all winter unless I know they will be parked long enough to completely dry them out.

Myosmith

My bikes stay in an unheated garage all winter unless I bring one into the basement to work on it. The air is bone dry outdoors all winter in MN and I have no worries about corrosion as long as the bikes are cleaned and lubed. BTW all of my bikes are steel.

HillRider

That same house has outside air being brought in and heated pretty continually. Unless you seal all the doors and windows, the humidity stays quite low.

FBinNY 

The humidity in homes depends on many factors; construction, heating plant, outdoor humidity, and humidity sources. As I said earlier, the tipoff is to look at the windows.

If you have fog or frost on the glass, the outdoor temp is below the dew point of your house, and you'll get condensation inside any closed vessel you bring outside. If there's no fog either the glass is well insulated, or the inside air is dry.

Sixty Fiver

We live in a semi arid climate and even winters are drier than most despite the snow... corrosion is not much of any issue if you protect the exposed steel parts.

Looigi

Heck, when I lived in the high desert, I could leave stuff out year round. The paint would rot off from the UV but the underlying iron or steel wouldn't hardly rust. If you handled it, it would corrode in the pattern of your fingerprints. I worked in a manufacturing facility that in the summer was cooled by swamp coolers. The relative humidity of the air as measured at the output of the swamp cooler was 15%! In HI and the Northeast it was a different story entirely.

cyccommute 

Relative humidity decreases as the air is cooled. The water carrying capacity of the air is a function of temperature. The relative humidity of the cold winter air is much lower than warm summer air even in areas where the humidity is high. Cold air just can't carry the same amount of water as warm air does. As you lower the temperature of the air, the dew point drops and the water precipitates out of the air. Cold damp winters still don't carry as much moisture as warm wet summers.

There is a caveat, however. If you heat cold dry air without adding moisture, the air dries. Forced air furnaces really dry out the air in a house. Radiator and hot water systems don't because they don't heat the air in the same manner. But if you use a heater system with that blows heated air through your house, it will be much drier.

Frames rusting out is due to other issues that aren't related to the relative humidity of the air.

When do you experience the most static discharges? Summer when the air carries more water or winter when it carries less? Static load is related to the amount of water that the air can carry.

That's not necessarily due to higher humidity in a house but due to the glasses being up against a warm, moist face with little air flow. Think about how your glasses fog when you stop moving on the bike. Also what happens to the fog on the glasses when you take them off?

Exactly. While not exactly sealed, there isn't a lot of opportunity for air exchange in a bicycle frame. Any water that gets into a frame is coming from direct water contact rather than through air flowing into and out of the frame. There's not much of a driver for the frame to breathe. Water spray getting into the headset either from above or below is probably the most likely entry point for water. Weep ports on the chainstay be the next likely place. If you were to seal those you'd stop any kind of air exchange within the frame. Do it when the frame is dry so you don't inadvertently seal in any trapped water.

The lack of air circulation within the frame would also exacerbate any water infiltration issues. Once the water gets in the frame, it's going to stay there. In winter, the water probably has some salt from road maintenance. The salt water is going to sit there and do its damage without an opportunity for the water and/or water vapor to leave.

rydabent

It is better to keep the bike cold. I have Stratus and and a trike. I store the bent in the basement over the winter, and keep the trike in the garage for the rare days that might be warm enough to ride in the rotten winter months. Even temps keeps moisture from forming and causing rust and corrosion.

FBinNY 

Do you not understand how dew, fog or rain happen? Relative humidity for any sample of air increases as the the temperature drops and and it's ability to carry the water vapor decreases, until the relative humidity reaches 100% and the excess water vapor precipitates.