Keeping an exposed chain lubricated has long been a problem. Bikes used for day-to-day transport traditionally have a fully enclosed chain for this reason, but with a derailer¹ gear changer that is impossible. There are of course specialised bicycle chain lubricants, but personally I find them expensive and not very effective. The last time I tried one, I found that whilst using the dry lubricant my chain had worn disastrously in less than a year, so I never got to use the wet lubricant (but at least it gave me an excuse to upgrade the chain rings and sprocket cluster). To me, the fact that you are supposed to use wet lubricants if you cycle in wet weather, and dry lubricants if you cycle in dry weather, has always seemed fundamentally wrong in a country that doesn't have a wet season and a dry season.
I've always had more success with traditional motorcycle chain lubricant. It's designed to be sticky enough not to spray off a high speed chain, but not so sticky that it quickly attracts dust and dirt. It's also designed to cope with higher mechanical stress than a bicycle chain will ever experience. It works well and it's cheaper than bicycle chain lubricants. However, given the poor, grubby surfaces that masquerade as cycling infrastructure in the UK, it tends to be in a pretty sorry state by the time I get around to cleaning my chain. Hence my experiment with dry bicycle chain lubricant, and hence my search for something better.
It's important to understand what is the problem if you want to solve it. A chain appears to stretch because the link bearing surfaces wear, and the bearing opens up. This means that under tension the chain no longer fits correctly on the sprockets and chain rings, so they start to wear to fit. Ultimately the entire transmission system will be destroyed and must be replaced. The key to not doing that too often is to keep those bearings lubricated. The snag is they are inaccessible, unless you are prepared to dismantle the chain link by link. Lubricating the bits of the chain you can see will will not have the desired effect unless the lubricant can work its way into the bearing surfaces. The lubricant must be engineered to do this. Like all engineering fields there is constant progress, so it's always worth looking for more advanced chain lubricants.
I did consider, and get as far as buying, some spray grease. This is dissolved in a light carrier liquid, so it tends to work its way in to small spaces. That makes it a potential answer, and it's relatively cheap, but it's not designed expressly as a chain lubricant, and once the carrier has evaporated it is quite sticky. That means it will probably attract dust and grit to the outside of the chain, since for all practical purposes it is impossible to lubricate the internal surfaces of a chain without getting lubricant on the outside.
Whilst searching to find out what modern chain lubricants are available for motorcycles, I came across Würth High Performance Dry Chain Lube. Würth is not exactly a household name, but I know from my day job that it is a very reputable engineering company². However, I had absolutely no idea they made chain lubricant. I guessed it was likely to be highly engineered, so I researched it, and sure enough it is. Like spray grease, the lubricant is dissolved in a light carrier - a very light carrier. In fact applying it is like applying lighter fuel to your chain. This is designed to wash out deposits on the bearing surfaces, and coat them thoroughly. It then evaporates off, leaving the lubricant in place. The lubricant is just tacky enough to adhere to the metal of the chain, but not so tacky that it attracts dirt to the outside of the chain. And its designed to be good enough for the high stresses associated with a motorcycle chain.
So it should work well on a bicycle chain, and after a year of use on my bike that appears to be the case. During wet weather the chain remains largely corrosion free, even though I don't have time to go to the extents some people do to stop their transmission from being destroyed by wet weather. It's not seen much in the way of salt, but that is highly corrosive and needs to be washed off your bike with clean water no matter how you lubricate your chain. In terms of gunk build-up, as you can see from the photo on the right there's almost none. Conversely the grease that has worked its way out of the jockey wheel bearings has attracted plenty of gunk. As can be seen from the photo, the link pin is less than 1/32" (0.8 mm) from where it should be, meaning chain wear is minimal. Despite being a hi-tec lubricant, at around £8 a can (which has lasted me a year) it's very far from expensive.
There are a couple of downsides. Firstly, if you believe the instructions on the side of the can it requires a lot of shaking before use (I can tell you the good practice on my part didn't last for too many applications). The second downside is that the contents are environmentally destructive. I would prefer it if that were not the case, but it's not as if one distributes it liberally and in concentrated form all over the countryside. Just don't empty it into your nearest pond.
So I think I've found my ideal chain lubricant. Until something better comes along, of course.
- Apply the spray to the chain where it passes over the sprockets.
- Keep the nozzle close enough to the chain that most of the spray goes on the central part of the chain, but not so close that there isn't some over-spray on to the outside. The over-spray coats the sprockets and provides corrosion protection for the outside of the chain.
- Spin the crank as you apply it.
- Apply little and often.
- Apply when you get back from a ride, not just before, to give the carrier time to work its way in rather than being spun off the chain.
- To avoid expensive damage to sprockets and chain rings, keep a close eye on chain wear and replace the chain as soon as the wear is excessive (1/16" measured over 12 links).
Measuring Chain Wear
For historical reasons all bicycles use imperial chains, even if the rest of the bike is metric. Each link should be 1" long. So chain wear is most easily measured using an imperial scale. Place the edge of a rule along the chain whilst the chain is under normal tension, taking care that it doesn't sag (hang the chain vertically if it is off the bike). Place the zero marker over the top of a link pin, and observe what is happening at the 12" marker (you can use a shorter rule if necessary, but the longer the rule the more accurate will be your measurement). According to Sheldon Brown, over 12 links:
- If the link pin is less than 1/16" past the mark, all is well.
- If the link pin is 1/16" past the mark, you should replace the chain, but the sprockets are probably undamaged.
- If the link pin is 1/8" past the mark, you have left it too long, and the sprockets (at least the favorite ones) will be too badly worn. If you replace a chain at the 1/8" point, without replacing the sprockets, it may run OK and not skip, but the worn sprockets will cause the new chain to wear much faster than it should, until it catches up with the wear state of the sprockets.
- If the link pin is past the 1/8" mark, a new chain will almost certainly skip on the worn sprockets, especially the smaller ones.
¹ Why use the French word "derailleur" in an article written in English, when there's a perfectly good English word that means exactly the same thing?
² I've not been paid in any way to write this review, and I have no personal connection with the Würth Group.