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Posted this in response to a chain question in one of the model specific forums and thought since I went the longwinded route, it really belonged here for posterity...enjoy!

OK, time for some chain ed-you-mah-kay-shun.

Chains have a few vital statistics. The first critical dimension is the indentifying number (520, 525, and 530 being the most common motorcycle dimensions). The 5 stands for the pitch in eights of an inch. :confused: Sorry. Pitch is the distance between pins (the little nubs that show through the sides on the hourglass shaped side plates). So, for motorcycle chains, they are 5/8 of an inch apart. Don't recall exactly how they come up with the other digits, but they designate the width of the roller. That is, a x20 is narrower than a x30. Because the rollers are different widths on 530s and 520s, the sprockets that mate into the gaps between the rollers need to be different widths. This is why you can't run a 520 chain on 530 sprockets (gap is too narrow and sprocket teeth won't sit down between the rollers), and neither can you a 530 chain on 520 sprockets (too much gap so their is dangerously excessive freeplay and wear).

A 530 is a wider chain which is theoretically stronger, as well as being more durable and spreading the accelleration forces across more area resulting in longer wearing components. A 520 chain is narrower resulting in less overall weight, but specifically less rotating chain weight for less gyroscopic force, less weight which has to be accellerated/decellerated during operation for less driveline power losses, and less unsprung and reciprocating weight at the rear wheel thanks to a narrower sprocket. The effects can be fairly marginal to somewhat noticeable. I figure it's about six of one and a half dozen of the other and see no reason to change unless you're due for a sprocket/chain change anyway. But understand that the higher the power of the machine in question and the harder it is ridden, the more wear will come into play (i.e. a 520 on a literbike is sure to stretch and wear sprockets faster than a 530 on a 600).

The other chain dimension in question is length, which is expressed in the number of links. If you know your length specifically (i.e. 108 links), you can order chains to an exact length. Or more often than not, you'll order the next size up and cut to fit (i.e. ordering a 110 link chain and cutting off 2). Check your manual for your specifications and remember that changing the number of teeth on your sprockets MAY require changing the number of links in your chain. When asking other owners for gearing recommendations, be sure to ask if the stock chain length worked. Usually a tooth one way or the other (i.e. dropping a tooth up front) won't make a difference, but sometimes two and most often three teeth (i.e. going from a 36 to a 39 rear sprocket) will cause you to need an extra link.

An X-Ring is an O-Ring with better marketing. Um...maybe. Not saying it's not better. I'm not an engineer so I don't pretend to know. But, an X-Ring is simply an O-Ring of a different shape that allows more oil surface to come in contact for better lubrication and less friction losses, as well as double the sealing points to better keep lubrication in blah blah blah :sleep: Want to know more, go to D.I.D. or RK or whoever's website and read up. I like X-Rings just because they seem to be the top of the line no matter the manufacturer and I somewhat buy the marketing hype of not trapping dirt and so on. Are they really better? Dunno, but I like gadgety things anyway and there isn't a huge price difference from quality O-Ring to marketed X-Ring these days.

Last comment before I realize I spent WAY too long typing all this. Change your sprockets and chain at the same time. Seriously. This isn't some mechanic's myth designed to get you to spend more. Now, I'm not talking about changing your 2000-mile-old chain just because you want to drop a tooth off the front sprocket. That would be overkill. But, if one or more components is just about gone, do all three (front sprocket, rear sprocket, and chain) all at once. Not doing so *WILL SEVERLY INCREASE* wear on any new components. I just this week changed all three for a buddy who thought that just changing his rear sprocket would get him by last time...2000 miles ago! The worn chain and front sprocket ate up his brand new rear sprocket like it was a snickers bar in a fat camp. And I've seen new chains go just about as fast when sprockets weren't changed in conjunction.

So, your choices when getting chains are the width and the length. Then you have to get sprockets to match the width of chain you chose, but you can play with the number of teeth if you wish to affect gearing. Good luck, and may I suggest picking up some GOJO or Lava or whatever extreme duty soap you like if you plan on doing the work yourself - chains are NASTY buggers.
 

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Quite well written, but I ALWAYS disagree with this statement....

nathanTX said:
Change your sprockets and chain at the same time.
It is a good general rule-of-thumb, but it all depends on the condition of the conponents. I've been running chains on my motorcycles for over 25 years, and a lot of the time I do change all three items at the same time, but not always.....here are two recent examples:

Example 1:

I logged over 20,000 miles on the chain on my Harley and finally broke the chain on a cross-country ride (chain #1). The only chain I had available to me on such short notice was a non o-ring chain. It was completely fried in less than 2000 miles (chain #2), by the time I got home. Upon inspection of my sprockets, because of proper lubrication and proper alignment, they didn't appear very worn at all, so.....I installed chain #3....a $100+ o-ring (paid $83 through my contacts). Now, 8000 miles later, everything still looks good. I'm hoping to get 50k+ miles out of this set of sprockets with three chains.

Example #2:

My 1998 Ducati ST2 was regeared with a 14-tooth front sprocket at 14k miles. The original front sprocket looked as good as the new one. Rear sprocket and chain were left alone. At 18k miles, the chain had some tight spots in it and was stretched a little more than I care to run them. MOST people would have let the chain stay on for another 5,000 or more miles and totally trashed the sprockets. Inspection of the rear sprocket showed NO side wear and very minimal wear between the teeth. I showed a friend of mine the rear sprocket, and he guessed the rear sprocket had 2-3000 miles on it. I replaced only the chain. Everything still looks good at 4000+ miles later.


I could list several other examples of times when I've not changed out sprockets with a new chain. My general "rule-of-thumb" is two chains to every set of sprockets.....with proper lubrication and alignment/adjustment. The trick here is that I don't run the same chain until the sprockets are getting severely damaged by a grossly out-of-spec chain. I've seen people destroy a set of sprockets and chain in less than 5000 miles because they were not aligned correctly nor ever lubricated.

Now, I WILL agree with you that the wear will be speed up a little bit compared to using new items, but when I can get another 10-20,000 miles out of a set of sprockets (new ones are $150), why not shave 2-5000 miles (25% of a 20k life expectancy) off of an $80 chain? So.....25% loss of $80 = $20....compared to spending the $150 on new sprockets that weren't ready to be replaced. That menas I just saved $130.


Here's what made me go to frequently inspecting the chain and sprockets and checking alignment......

When I was in my late teens, I had a 1983 Husqvarna WR-430 (a very torquey 2-stroke engine). I had a chain and set of sprockets that looked decent if they were on my old Honda XR-200, so I decided to go on a long trail ride. Turns out, I needed MUCH more meat on my sprocket teeth with this bike. With my little XR-200, I could wear the hell out of the teeth, even to the point where they would be bent over a little bit, or occasionally break a tooth or two off. With this Husky, out in the middle of no where, I rapped the throttle a little too hard......and ripped every single tooth clean off the front sprocket. There was barely enough raise on the front sprocket for the chain to grip. Much over idle, and the chain would slip...jumping from nub to nub on the front sprocket. Any slight incline or increased load placed on the chain, and it would slip and hop over the sprocket. A 20 minute ride home took me over an hour, and I had to push the bike in several places. That was the day that my views on how I treated my chain and sprockets changed (with my dirtbikes that use non o-ring chains.....after every 2-3 rides, the chain comes off, soaked in kerosene, every link is worked until it moves freely, and then it is dried and lubricated).
 

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Don't recall exactly how they come up with the other digits, but they designate the width of the roller.
A 520 chain is 5/8" pitch X 1/4" roller width. If you divide 1/4" (.250) by 20 you get .0125". So if you use .0125 as the multiplier of the last two numbers you can figure out the roller width:
A 525 chain is 5/8" pitch X 5/16" roller width (.0125 X 25 = .3125)
A 530 chain is 5/8" pitch X 3/8" roller width (.0125 X 30 = .375)
 
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