Can all night soaking in WD40 cause chain rust?
 

Thank you

:thumb:

I forgot about the chain one time, and left it soaking all night.
I noticed a few weeks later that there was some corrosion on the inner plates.
It could've happened from rain, but I'm not sure.

Not directly.
Indirectly; after the WD40 all evaporates away, what is left to prevent rust?

doubt it. WD displaces water, which usually has salts and other such catalysts that cause steel to oxidize.
after WD evaporates it leaves a fairly weak oil on top so the rust you see might have just been displaced rust from the inner plates.

Thank you

What about super-cheap and nasty supermarket aerosol degreasers?

If anything, it might have just cleaned off the dirt that was covering up the rust. ;)

if there's no protective coating, like oil or paint, on the steel, it can rust from the moisture in the air.

it really depends on what's in the steel alloy that inhibit oxidization.

To prevent rust you should lubricate a newly cleaned chain with chain lube as soon as it is dry.

no harm in soaking w WD40
 

WD40 will remove oil and grease.
As with WD40, once power degreasers leave the chain bare with no rust protection or lubrication. Be careful with cheapo degreasers, high phosphate stuff can leave a residue of degreaser that'll damage paint, pollute drinking water and prevent oil from working. Wash thoroughly with water, dry then lube with chain oil.

Yes^^^ And WD-40 doesn't leave squat for lubrication. It will work into the chain, and remove all the oil that was in there. Then it evaporates. WD-40 can actually be worse than using no lubricant at all.

http://bicycletutor.com/no-wd40-bike-chain/

if it's just sitting there doing nothing then WD-40 will inhibit oxidization. that is what it is designed to do.
for a chain you're actually using WD-40 is too thin.

The WD-40, or what ever other degreaser you use will not directly cause rust. It will however remove the former lubrication that was preventing rust. If you regrease after using the WD-40 you'll be fine.

WD-40 contains about 30% oil. Once the solvent evaporates, it DOES provide protection from rust.

which washes off in the first few kms, and then it rusts.

Some of you folks will believe any ridculous crap posted on the internet. That video is hilarious, since the guy making it apparently believes what he's saying.

WD-40 contains about 30% oil. It is a light weight oil, but it's plenty heavy enough to last for a least 100 miles on a bike chain. Flushing a chain with WD-40 is not the least bit harmful. As long as the chian is wiped before it's applied, the WD-40 will help to flush out the grit that accelerates wear.

I've used a homebrew lube that contains even more solvent and less oil for years. I apply it every 100 miles at the minimum. I've used a Campy 10 chain for 6,000 miles and measured only about 1/64 of an inch per foot elongation, so this very thin lube did a great job of preventing wear at the pins.

Perhaps if you ride in the rain, but in normal use, that oil is good for at least 100 miles and perhaps far more.

Riding is wet conditions always calls for a heavy lube.

Well it's wet and winter here... not sure what's happening down there!

The old geezer at my shop tells people that WD40 is a poor substitute for proper chain lube and can cite many examples of folks coming in with badly rusted and seized chains that thought WD40 was adequate. Another problem is that a lot of people don't clean and lube their chains often enough or in a proper manner.

He'll go on to tell you that WD40 is a solvent and de-greaser and the quantity and quality of the oil in WD40 is not suitable for bicycle chains whereas home brew lubes tend to use different base oils and do work very well.

He is also pretty firm on the less is better methodology of lubing chains as they only need to be lubed on the inside and any residual lube just works as a dirt magnet... we live and ride in a very dusty climate (summer) and a cold, wet (and dirty) climate in the winter that is hard on drivetrains.

He seems to know his stuff backwards and forwards... people trust his advice.

He is of course... me.

And I would also be hard pressed to find any other mechanic here who would tell anyone that WD40 is adequate as a chain lube.

Because it isn't.

I forgot who told me about this but the WD in WD-40 stands for water displacement

It depends. I know that soaking in Simple Green is not recommended, and that Simple Green has come out with an aircraft-specific formula for that reason.

In fairness, the OP talks about using WD40 and re-applying every 100 miles, presumably about once a week, say. For a chain to get so rusty it seizes, the bike generally has to be left unridden for quite some time and in appalling conditions. So the people you're talking about, I have a feeling that what happened is the bike was "lubed" with WD40, ridden for 2 miles, and left in the rain for 6 months. That's a bit of a different situation than the OP.

I wouldn't use WD40 as a lube, but I don't think it will cause a chain to seize overnight.

WD-40 does contains light petroleum distillates but the 'oil' in it is a light paraffin oil related to kerosene or #2 diesel. As an 'oil' or lubricant, that cut of petroleum is pretty poor. The motor oil most home brew systems use is much thicker and would stick on the chain better than the 'oil' in WD-40...even if it's highly diluted.

Below is the composition of WD40 from its MSDS. Most of the stuff other then the 'Base Petroleum Oil' is there as solvent and propellent.

I'm not suggesting that people use WD-40 for sloppy wet winter riding, but if you are riding in those conditions, I'd be wiping and relubing the chain after every ride, particularly if the water has salt in it.

I'm no spring chicken either at 55, but I'm no retrogrouch. I've got two bikes with Campy 11 speed drivetrains and a winter/trainer bike with Campy 10. I have an mechanical engineering degree and I've been wrenching on bikes for 25 years. I've done some serious chain wear testing and tried a number of different lubes, just in the last 10 years. I first tried ProLink about 10 years ago and soon found out that this pricey lube was nothing but mineral spirits and oil. Now I make my own chain lube for pennies per ounce.

I've done thorough chain cleanings with the chain off the bike and used WD-40 as the final step in the process, right after rinsing the chain in hot water and wiping it partially dry. I've had no problem at all using WD-40 as chain lube for the first couple of rides after cleaning. Beyond that, I switched back to my normal homebrew lube of 3-4 parts naptha to one part synthetic motor oil or synthetic 80/90W gear lube. Lately, I just apply my homebrew to a freshly cleaned chain and find that it displaces the water and prevents rust just as well.

I ride in Colorado wear it's dry and dusty quite a bit of the year. I don't ride in the wet. In the winter, the chances of hitting ice are too great for me, so I wait for the most of the snow to melt off before I go out. The little puddle splash or occasional stretch of mountain road dampened by snowmelt doesn't get my chain wet.

This is really the point I and many folks are trying to make... WD40 is a lube (but a poor one) and there are much better products out there and most people do not clean and lube their chains every 100 miles.

I don't unless the conditions are heinous.

One of the best mechanics I know (not me btw) makes his home brew with WD40 and motor oil in a 3 to 1 ratio... because WD40 is basically mineral spirits.

It works really well.

I don't think anyone's contending otherwise. The guy you're responding to says he uses other lubes primarily, but that WD40 will get you by in a pinch if your chain is a gritty disaster and you're out of lube. I think that's true, and that the horror stories of seized chains might be a bit overdone.

Some people also seem to claim that you shouldn't even use WD40 as a chain *cleaner*, which seems silly to me.

The whole chain cleaning thing is too much of a holy war anyway. I figure just lube it with something that will stick around (not WD40, to be sure), and wipe it down very well afterwards. Then just ride your bike.

So much of this depends on where you live and what kinds of conditions you ride in... in a really dry climate you might be able to get by with some pretty minimal upkeep whereas most of us ride in varied conditions that has a more profound effect on our chains.

Folks who routinely use WD40 on their chains also seem to be the same folks who are not as up to speed on bike maintainence and any kind of neglect when you are using WD40 will result in some nasty looking chains.

To the OP... soaking your chain in WD40 won't cause it to rust but you should not expect that WD40 to offer any significant protection when things get nasty or the miles start piling up.

Using a proper lube avoids many of these issues.