Technical Info on Chain + Sprockets and chain conversions

Chain Size & Pitch

Below table contains chain pitch, roller width (E), Chain Height (F) and roller diameter (H) for common motorcycle chain types in mm and inch:

Proper chain maintenance is essential for safety, maximum performance and a long chain & sprocket life. The interval at which a chain needs maintenance depends on the type (sealed or not) and the way it is used and is mostly described in the User Manual. To be on the safe side, have a look at your chain after each ride and maintain it after every 500 km or about 300 miles. But like I said, these intervals differ per bike so check your manual !

Lubrication
Although most modern chains are sealed and pre-lubricated, the external of the chain (rollers and side blades) need to be lubricated (very) regularly. This will also keep the chain clean and corrosion free. Use the intervals mentioned above but when driving in wet or extremely dusty conditions, lubricate more often ! Also lubricate the chain while it is still 'hot', that is following a ride.

Cleaning
Although there are many products to clean a chain, Tsubaki recommends the use of a "moisture displacement lubricant" to clean chains and to not use any dissolvent, petrol, diesel, detergents, steam-cleaner or coarse brush because it will damage the chain. In fact it will damage the seals which will cause the chain to wear very fast.

How to Lubricate/Clean
To spread the lubricant over the chain, it must be rotated while lubricating. Therefore if you have a center stand use that, if not, get some help an tilt the bike on the jiffy so the rear wheel is off the floor.

Because using a spray always causes a 'cloud of lubricant' that will descend on your rim and  tire so maybe it is a good idea to protect them using an old newspaper or piece of cardboard. Try to aim the spray between the side blades and the rollers like illustrated below, first the left side. Spray and rotate the rear wheel at least 3 complete revolutions. Then do the same on the right side of the chain.

After spraying, you need to wipe off the excessive lubricant using a dry and clean cloth.

Adjusting chain tension
Both a to tight chain or a to loose chain will wear out faster or even cause danger so it is important to keep the chain at the right tension. This right tension will differ per motorcycle and is often described in the Owner Manual. Most common method for checking is placing the bike on the center stand when available or on a paddock stand or tilted on a jiffy and measure the slack of the chain in the middle like illustrated below.

Turn the rear wheel slowly until you find the position where chain is tightest. Push the chain up pressing with a finger at mid-length of swing arm. The lower stretch of chain must have a slack of about 25 mm 1". The exact slack depends on the type of chain and length of the swing arm and should be checked in your User manual. If not available, the example above is a good average.

Sprocket Alignment
To prevent noise and fast wear of the chain, the sprockets must be aligned in 2 direction:

When the chain tension needs to be adjusted, make sure that the rear sprocket is aligned with the front sprocket.
To adjust the tension and/or alignment:
Slacken the nut (1) of the wheel shaft, tighten (turn clockwise) or slacken the screw (2) on either side of the swing arm equally to increase or reduce chain tension. If you are slackening the chain, you will have to push the wheel forward. Make sure you have adjusted to the same setting marks (red) on both sides of the swing arm. Refer to the position of the slider (4) on both sides.

If there are no marks on your swing arm you can either create them your self or measure the distance of the slider to the end of the swing arm (green arrow) on both sides and make sure they are equal. This will ensure perfect wheel alignment and thus a perfect sprocket alignment. If the rear wheel and sprocket is not aligned with the front sprocket, both chain and sprockets will wear very fast.

Chain & Sprocket replacement

Does a chain really "stretch"? The term "stretch" is misleading. A chain will elongate when the pins and bushings wear down. This is due to poor lubrication, under sizing and overloading of the chain. As the components thin, the space between the pins and bushings increase, thus making the chain longer than originally. For transmission chain, there is almost no risk of fatigue failure when wear elongation is less than or equal to 1.0 percent for O-ring chains.
For Non O-ring chains the maximum wear limit is usually 2%.

A direct measure of chain wear is the extension in excess of the nominal length of the chain. Lay the chain on a flat surface and, after anchoring it at one end, attach to the other end a turnbuckle and a spring balance suitably anchored. Apply some tension load by means of the turnbuckle.

Of course this is more easy with a 'broken' chain that has 2 ends but it is also possible with an endless chain, just measure part of the chain and count the # of measured links (as many as possible):

Measure length ‘M’  in millimeters from which the percentage extension can be obtained from the following formula:

                                     M - (X * P)
Percentage extension =    -------------         Where X = # of pitches measured, P = pitch (in mm for more accuracy)
                                    (X * P * 100)

As a general rule, the useful life of the chain is terminated and the chain should be replaced when the percentage extension reaches 2 per cent.

A popular upgrade is a so called 'chain conversion' what actually is replacing a 'big heavy' chain and sprockets by a 'small light' chain and sprockets. Most powerful modern bikes come with a strong chain type like a 525, 530, 532 or even bigger. By replacing it by a smaller and lighter one like a 520 chain people hope to gain acceleration.

The advantages of the 'conversion' are:

I often get questions about what sprockets to buy when doing a chain conversion. As the number of sprocket teeth has got nothing to do with say a 630 -> 520 chain conversion, you are only changing the type and sizes of chain (and sprockets, not the number of teeth), to keep your current final drive ratio, you should buy sprockets with the current amount of teeth. For size differences between all different chain types see the tabel at the top of this page

If however at the same time you also want to change your final drive to get some more low end torque you could change your final drive ratio to achive that as you are already buying new (diffentent type) sprockts anyway.

Personally I would not do it as you will probably not even notice the difference unless you are a professional racing driver and you are able to replace your chain before every race. Just keep your the stock chain in good condition by cleaning and lubricating it regularly. That saves you some money so you can go to the gym and loose some 'unsprung weight' your self.... ;-)

Sprocket Diameters

When changing sprockets it is important to check if a bigger or smaller sprocket will fit on the bike and if it will not cause issues.
When using a smaller sprocket, especially on the front, the angle of the chain will change and the chain might start touching the swing arm.

When using bigger sprockets, also especially on the front, it is important to check if there is enough room for the sprocket with the chain on it. The Gearing Commander cannot determine the amount of room on your specific bike but it can calculate the sprocket (pitch) diameter and more important the total diameter of the sprocket with the chain or belt on it; the Chain- or Belt-diameter.

When that is known, you can go to your bike and check if a 'sprocket & chain'  with that size can actualy be fitted to it. If in doubt you could create a cardboard sprocket and place that on your front-sprocket axle. Of course it would not have to have actual teeth and have the outside diameter as the calculated Chain- or Belt-Diameter (Cd or Bd). If that can be fitted with still some room to spare, you should be Ok. Go to this additional Help-Page on Sprocket diameters for details on the calculated diameters.

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