There's plenty of threads throughout the forum that address "what is best for my bike?", or "what is best for my budget?", or "what lasts longest?", or "what ratio is best?", and a myriad of other similar questions.
So I thought I might drag the whole Chain and Sprocket topic together a bit.
If I have screwed anything up, typos, etc, please feel free to comment. I need some practice with technical writing.
First up, the bits of interest:
- Chain
- Front Sprocket
- Rear Sprocket
- Lubricating system
- Supplementary lubrication
CHAIN:
Critical specifications are:
- Pitch is the distance between two adjacent pins, measure in eighths of an inch.
- Width is the roller width, or the nominal distance between the side plates, also measured in eighths of an inch.
- Load Rating
- Lubrication Seal Type
Decoding a chain number goes like this:
525ABC-X
5 is Pitch, 5/8"
25 is Width, 2.5/8" or 5/16"
ABC requires a check with the manufacture to find load rating and purpose
X usually indicates and O-ring that has a "X" shaped cross-section
or,
R4 SRS 530
R4 refers to Road Chain
SRS refers to the type of patented O-ring
5 is Pitch, 5/8"
30 is Width, 3.0/8" or 3/8"
If you shop around for chains you'll find there is no strict standard other than the 3 digits that indicate the dimensions, for everything else you really need to read the box or check with the supplier.
Regardless of the type of O-ring, be it XYZ SRS or any other name, the purpose is to keep the lubricant inside the chain. This lubricant is not replaceable; it's put there in the manufacturing process and stays there as long as the seal is good. Any lubricating you do is to minimise wear between the roller and the sprocket, and by keeping the chain generally wet with lubricant you can help preserve the O-rings and prevent corrosion.
I wont bother mentioning standard chains, without O-rings, other than to say they have no place on a modern machine. They're only suitable for classic/vintage class motorcycles when the owner is a purist. Only fit one to a TDM if it's your only option to get home from Timbuktu. You will not save money using this old tech' on a TDM. If you're trying to save money you're better off converting to a wider 530 C&S set.
Conversion C&S Sets:
Why do it?
525 chains are not a popular items whereas 530 chains are. Pricing is almost always dictated by supply and demand, so you can get much better deals on 530 chains... but you must use sprockets that match! Thankfully today's manufacturing techniques mean that most suppliers can make any combination you could want, http://www.chaingang...prockets.com.au for instance. (If someone can supply me a link to a good Euro based sprocket supplier, I will post it here.)
The obvious advantage of the 530 chain, over the 525, is that it has a larger surface area to spread the load which results in less wear.
The perceived disadvantage of the 530 chain is that it is heavier and will require more energy to rotate and has a greater internal friction loss... and it does... but in the scheme of things the difference is minute and you won't notice a difference at the petrol pump. What you will notice is a smoother and quieter final drive; that little bit of extra mass helps dampen the actions of chain catenary (droop) and harmonics in the final drive assembly.
Conversely some boy-racer types want to fit lighter C&S sets in a bid to go faster, so replace a 525 with a 520. Usually the only great increase is the rate of replacements and the number of pit stops caused by premature wear and/or breakage.
Drive Chain Slack:
(TBA... was too slack to do this before dinner.)
Supplementary lubrication:
With O-ring chains the most critical lubrication is already taken care of but it is important to lubricate the chain to prevent corrosion and to maintain the O-rings. It's also easier to clean an oily chain than a dry chain.
Whether you paint on oil with a brush, wipe it on with a rag, spray it from a can, or fit a mechanical oiler to the bike, it does not particularly matter as long as you keep the chain damp with lubricant.
Oil is better than grease or wax because it will creep in between the plates, rollers, and coat the sprockets.
As a rule of thumb: if you touch the chain and your thumb comes away clean, you need to oil it.
Sprockets:
They need to fit in five critical dimensions:
- Shaft spline, or mating plate. Fairly obvious; it must fasten on tight.
- Offset. Front sprocket must be in the same plane as the rear sprocket. This can be a problem when using sprockets from other models of bike.
- Pitch, must match the chain.
- Width, must match the chain.
- Number of teeth, diameter. This will determine the final drive ratio.
Final Drive ratio:
The OEM decided on a one size-fits-all ratio that may or may not fit what you want to do with he bike.
Given the high power to weight ratios that most modern sport bikes have, it's probably more common that anyone wanting to change the final drive ratio is going to lower it. i.e. make the bike go slower but have more usable power. If you were trying for a land speed record you might want to raise the final drive ratio.
What fits which bike and what are the available alternatives?
Gearing.jpg 102.9KB
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What works best and can I just use any sprocket combination if they match my chain and fit the bike?
Yes and no...
Yes:
Any two sprockets that fit will give you drive at the rear wheel, but it's not just that simple.
First you need to work out what engine RPM you will need/want at a given road speed. http://www.gearingcommander.com is a great tool for this, many bikes including the TDM's are listed, and there is the great JBX's TDM specific website http://www.jbx9.alla....php?page=RATIO
No:
Some ratios will force chain lengths that may not fit within the adjustment range of the rear axle.
Some ratios and chain lengths will create a pattern of wear that can promote premature wear and tight/loose sections of chain.http://www.gearingcommander.com can show you whether the combination you have is optimum for wear, or not so good.
For example:
The stock TDM900 has a 118 link chain with a 16 tooth front and 42 tooth rear sprockets, it gives a wear pattern like this:
118-42-16.png 40.74KB
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A common mod for the TDM900 is a 15 tooth front, with the stock 42 rear, sprocket and still using the 118 link chain. It wears in this pattern:
118-42-15.png 46.13KB
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Another similar ratio is 15/43 with 118 links:
118-43-15.png 53.72KB
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This is the optimum wear pattern.
This pattern shows that every tooth visits every link, by using GearingCommander we can see it take 645 revolutions of the chain to complete the cycle.
16/45 with 120 links:
120-45-16.png 17.29KB
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This is the worst wear pattern.
With a wear pattern like this you can see that the same teeth are going over the same limited sections of chain, this is how tight/loose spots develop. It only takes 6 revolutions to complete this cycle.
16/46 with 120 links:
120-46-16.png 33.46KB
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Images created using the on-line Spirograph at http://www.artbylogi...spirograph.htm#
The chain length is used as the stator, or R=(number of links), then a r=1 d=1 rotor will indicate each link on the chain.
To show the sprocket transits use r=d=(number of teeth).
If every link is visited by every tooth, you've got an ideal ratio... and a pretty cool graphic... if you get something that vaguely resembles a pentagram, then it will be a devil of a thing to maintain and adjust, and come to a costly premature end.
Edited by AzzA, 04 June 2013 - 09:08 am.
great info though, very nice of you to write it up.. 
Sorted and on the Road Mick 
