Saturday, February 23, 2008

Chain, chain, chain: Observations on the bicycle chain...

I spend a fair amount of time reading cycling related websites like Cyclingnews, VeloNews, and Bike Radar. It's my need to want to know what is going on in the world of cycling outside my slice of the 1800's with cars out here in West Marin. I also want to be able to converse with customers knowledgeably about topics in cycling and new bike parts coming down the pike.

Because of this quest for knowledge, I know that chains and the brand of chain on bikes is a somewhat hot topic. Basically, a chain is what drives a bicycle forward. It is made of inner and outer links and a roller. All the parts are held together by a pin. The pin is the center of controversy as to why someone likes or dislikes a chain. Me, I like chains that are quiet.

For all intents and purposes, I will make the assumption that there are two brands of chains - Shimano and SRAM. There are actually several others. Campagnolo which you only use if you have a Campagnolo equipped bike. Whipperman which you use if you have a little extra cash to spend (they really are nice chains, though). KMC which are okay, but more often found as OEM equipment - although, they do make my favorite single-speed chain, the Z610HX.

Okay, back to Shimano and SRAM. Both chains are interchangeable in either a Shimano or SRAM drivetrain. Both chains used pins pressed into the outer links to keep the chain together. Both chains use some form of "mushrooming" on the end of the pins to enhance their ability to stay connected.

The area where they differ is how one connects the chain together during the initial installation. Shimano uses a special pin that consists of a guide pin that helps the main pin, with mushrooming on both ends, get inserted into the tight fit of the outer links. SRAM uses a special two part outer link that snaps together. One must use a chain tool with the Shimano chain, but can install SRAM's connector by hand. That is, of course, after a chain tool has been used to cut off excess links if necessary.

SRAM link on the left, Shimano pin on the right.


So, what we have are end users who hate Shimano chains because they claim they break during use. Well, they break during use because the special connector pins were likely installed incorrectly. I've never had a Shimano chain break. End users, however, love SRAM chains because they are easy to install, and, they claim, don't break.

Back to the sub-title of this post: Observation Time. Over the past couple of years, since SRAM has introduced road components, I have noticed an interesting sub-theme. SRAM sponsored athletes running Shimano chains. These teams are paid to run SRAM components, yet they continue to use Shimano Dura Ace chains. Why? Could it be that the mechanics and riders feel that Shimano chains are better? After all, that would be a pretty fair assumption since it is absolutely crucial to these folks that their equipment not fail. I noticed that Levi Leipheimer's SRAM equipped/sponsored TT bike sports a Shimano Dura Ace chain. Seeing his bike, I recalled that I'd seen other SRAM sponsored teams using Dura Ace chains as well such as Iban Mayo's ride at last year's Tour de France.

Why do you not hear about these pros breaking their Shimano chains? Because their mechanics know how to install the chains. How does one install a Shimano chain? Easy. Here's my step-by-step chain Shimano chain install (convenient because I've got to replace the chain in my cross bike anyway, or rather flip it as suggested by Wayne Stetina further in this post).

1. Remove old chain and consult Resource Revival to find a shop that will send your chain in for recycling into cool bike related items.

2. Fit new chain on bike and remove excess links. On a road bike, run the chain around the large chainring and through the derailleur and smallest rear cog. The chain length is correct when the two pulley wheels are at 90 degrees (perpendicular) to the level ground. A mountain bike chain length is determined by running the chain around the large chainring and the large rear cog (without running it through derailleurs), bringing the two ends together, and then adding two links (that is one inner and one outer - erring on the longer side if necessary) allowing the chain to be shifted into the big-big combination without tearing the derailleur out of the dropout.

Road bike sizing.


3. This is a crucial step. The orientation of the chain links should be that the new pin should be positioned in the outer link so as the chain runs around the cassette cogs, the pin leads the way through. There is a great article by Lennard Zinn on installing a Shimano 10-speed chain that explains in detail why you want to install the pin in the leading hole in the plate. In another Zinn article on velonews.com, he notes that Shimano's Wayne Stetina recommends flipping the chain over to double its life (which is what I did in the photos here).



4. Use a good quality chain tool (not one of the chain tools included with multi-tools). A good chain tool will ensure that the new pin will be inserted straight into the new chain. Make sure that the tool's pin is not bent, replace if it is bent.

5. Slowly drive the new pin into the chain. I always apply a dab of grease to the new pin to decrease friction as it's driven into the chain plates. You will feel pressure as you screw the tool's handle down as you press the pin into the chain. When the pin is fully inserted, you will feel a noticeable drop off in the pressure of the handle. The pin is in. Don't continue to drive the chain tool handle in. Back off, remove the tool and inspect the pin. The guide part of the pin will be protruding from the opposite end. Before you break off the guide part, feel the end of the pin where you pressed it into the link. It should feel flush. If you are confident that the pin is properly inserted, break off the guide with a set of pliers. If you did it correctly, the link with the new pin will move freely. Don't bend the chain side to side.



6. If you are removing an existing chain and reinstalling it, don't remove it at the link that already contains the special pin. Choose a spot in the chain's length opposite the existing special pin.

7. Go ride!

(What's playing: Elvis Costello Big Tears)

I thought more about the chain and why they break so I added a couple items to the list.

8. While partaking in item #7, learn to shift. I believe most chains are broken because shifts are forced or undertaken under full load. Shimano's advent of Hyperglide was touted as being able to be shifted under full load. Just because you can, doesn't mean you should. Shifting under full load puts a huge stress on the chain. Sure, there are times then you have to shift under load, but for 99% of the shifts, you don't have to. Learn to back off on the pedal pressure as you are shifting. Your chain will like you for this.

9. Inspect your chain periodically. You inspect your frame every once in a while, don't you? Well, you should. Check the chain to make sure the outer links are not in the process of being pried away from the pins. Spin the crank backwards and visually inspect the chain. A link that is in the process of peeling away from the pin will be very noticeable in contrast to the other links.

(What's playing now: Black Mountain's downloadable concert on NPR's All Songs Considered Live Concert Series. Hey, I had to check it out just because of the name - pretty good stuff.)