Chain Maintenance & Keeping An Eye On Chain Wear

I thought about doing a repost of last year’s “Tandems & Spring Maintenance” entry, but decided to simply post a link to that and focus on chain maintenance instead.  So, here’s the linky to last year’s Tandem Maintenance Reminder.

Chain Maintenance

Keep on top of it!  Seriously, never forget that a drive chain is a consumable item analogous to the oil or spark plugs in the engines that power vehicles: it needs to be checked and replaced to make sure it’s doing it’s job without doing damage to other parts of the drive train.

Chains and the sprocket teeth they mesh with are all designed using a 1/2″ pitch and as the pins and rollers that connect the outer and inner plates of a chain wear down from friction the pitch increases between each pair of links. Most folks commonly call this chain stretch because, well… the chain truly does appear to get longer even thought the side plate lengths remain unchanged. However, if you let the chain pitch become too long the very expensive cassettes and chain rings that they interface with will start to become damaged.

If you’d like to dive into the esoteric aspects of chains, cogs, chain wear and lubricants you can find a wealth of information on-line at these two Websites:

• The late Sheldon Brown’s Site.
• Pardo Net

If you’ve read through these two sites then you’ll now know something about chain wear measurement and measuring devices. Suffices to say, most of the chain checkers on the market only approximate chain wear, aside from the only one that most cycling science icons agree is accurate: the $70 Shimano TL-CN41 

Me, I use the Park Tools CC-2 Chain Checker, which only costs about $24 because that’s just what I happened to buy about 10 years ago; it was and still is “good enough” for easily monitoring chain wear.  However, I supplement the use of my CC-2 with a steel rule when making the final decision on when to chuck a chain.

Case in point, after last weekend’s ride I was reminded that our drive chain was in need of lubrication as the tell-tale sound of squeaky links was very obvious on some of the steeper climbs.  So, after getting home I put the Calfee in the work stand and prepared to remove the chain so I could give it a bath in solvent and then throw it in the Fry Daddy for a nice hot paraffin wax bath.  But, before going to all that trouble I thought I’d do well to check the chain for wear, as it had about 2,200 miles of use since being installed.

Again, I don’t have the highly accurate Shimano TL-CN41 in my tool box but have always gotten predictably easy to interpret results from my well-worn Park Tool CC-2 Chain Checker.  The ‘trick’ to using these lesser chain checking tools is understanding that they are actually telling you as well as baselining their calibration markings to the chains on which you use them.

In regard to the CC-2, it’s not all that unusual for a new chain to show somewhere around 15% “wear” right out of the box. When the thing starts to read in the 75% wear range it’s about time to change the chain.  I try not to let my chain’s “stretch” to the point where my CC-2 reads 100% wear, as by that point the expensive stuff has been damaged: really.

These are photos of both the “old” chain (above ruler) and new chain (below), noting I actually let my chain wear a little longer than I like, almost to 3/32″.  You can see what that looks like with my CC-2, i.e., about 80%. And then the third image is a representation of just how much longer the old chain showing 3/32″ of wear is vs. a brand new chain hanging side by side.

  

Again, I always go back to the ruler for passing final judgement since it continues to about as reliable as anything else, short of the $70 Shimano tool. In terms of how to use a ruler to check chain wear and how to interpret the results, let me just quote from the linked information at Sheldon Brown’s site:

Measuring Chain Wear

The standard way to measure chain wear is with a ruler or steel tape measure. This can be done withoutremoving the chain from the bicycle. The normal technique is to measure a one-foot length, placing an inch mark of the ruler at the side of one rivet, then looking at the corresponding rivet 12 complete links away. On a new, unworn chain, this rivet will also line up exactly with an inch mark. With a worn chain, the rivet will be past the inch mark. [For accurate measurement, the chain should be held under some tension — either on the bicycle, or hanging vertically. — John Allen]

This gives a direct measurement of the wear to the chain, and an indirect measurement of the wear to the sprockets. In English measurement:

• If the rivet is less than 1/16″ past the mark, all is well.
• If the rivet is 1/16″ past the mark, you should replace the chain, but the sprockets are probably undamaged.
• If the rivet 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 rivet is past the 1/8″ mark, a new chain will almost certainly skip on the worn sprockets, especially the smaller ones.

Of course, now that it’s time to break out a fresh chain I must once again wrestle with the choice of lubrication.  I’ve been using ProLink Gold (aka, ProGold) on the timing chain for the past 6 months and have been really impressed with it.  It’s not as clean as my beloved hot melt paraffin lubrication mix but with regular chain wipe downs using a terry cloth towel after every other ride it does keep the chain nicely lubed without becoming a grunge magnet.  However, if you put your hands on the chain it’s definitely going to leave you with a greasy mess, something wax doesn’t do.

So, as for right now, the Calfee is hanging it the garage without a chain as I mull over using the ProLink Gold on this new chain to see if it will deliver longer chain life at the cost of having to deal with a greasy chain.

Of course, with a current wind chill of 15°F there’s no hurry to make that decision today.