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Comment by laputan_machine | Hacker News Reader

I wouldn't trust a bike mechanic that uses WD-40 as a chain lubricant. The only possible scenario I can think of is if they live in an extremely dry place with minimal chance of rust. I live in the UK, if you use WD-40 as a lubricant your chain will be rusty by the end of the week. Use an oil lube (e.g. I use Finish Line Wet).

Edit: And it's not "going all religious", it's because I do 6,000km on my bike every year. I know through my own mistakes that WD-40 is not a good chain lube.

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I know an (e)bike rental operation that uses wd40 almost exclusively as chain "lube". Their current ebikes have something like 4-5k on the odo, powertrains still the original ones. But they clean/apply the wd40 to the chain between every rental, I guess that makes a difference. So my guess is that if you use wd40 often enough, it is fine.

Are you sure it's WD40 and not WD40-branded chain lube? I use that on my motorbike, and it's nothing to do with the WD40 spray - just the same parent company.

WD-40 IS good for cleaning chains and other parts of the drivetrain but not great as a lube. My guess is the convenience of a quick spray and turn of the pedals, then back out to rent outweighs what a bike mechanic would do for their own ride.

WD-40 does not have sufficient film strength. Constantly renewing it won't fix that.

It likely works for that e-bike rental operation because there's almost zero load on the chain; tourists renting e-bikes are soft-pedaling and letting the hub motors do all the work.

My guess is that WD-40 is being used just to keep the chains clean so tourists don't complain about greasy marks on their legs...or because they see the sparkling chain and think the bikes are "well maintained." Being so light, it would also be easy to wipe off various parts of the bike, again helping it look "well maintained."

Center motor, so if anything, the load is higher on the chain than normal bikes.

I am not sure how much more than 5k you can realistically expect for a lifetime for an ebike drivetrain regardless how you maintain it. You need to clean the bike anyway between the customers. If a quick wipe with wd40 gives you 5k, I am not sure if the extra miles on the drivetrain justify the extra work and extra cost of a fancier maintenance.

A belt would solve those problems or a chain guard.

I do use it on shift cables and derailleur mechanisms. Mostly because I haven't figured out anything that is a better solution.

Just to clarify: I agree that it's not a very good chain lube in general (and I don't use it myself anymore after having tested it), but I'm also not going to distrust people applying it as such because depending on the situation it is actually usable. Also see sibling comment.

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