Different sprocket sizes – larger or smaller – what is the impact on performance?

Final drive ratio.

Divide the rear sprocket tooth count by the front tooth count and you have the final drive ratio. For example: 35 / 15 = 2.33:1

If you want to change your gearing, you can calculate the impact of the change before you purchase the new sprockets.

For example: your bike cruises at 60 mph / 4,000 rpm and has a final drive ratio of 2.33:1 – if you want more acceleration, changing a 35 tooth sprocket for a 37 tooth sprocket and leaving 15 tooth on the front changes the ratio to 2.47:1 (37 / 15 = 2.47:1). Divide your cruising RPM by 2.33 and multiply by 2.47. Using the example from above, 4,000 rpm becomes 4,240 rpm at 60 mph.  You’ll get more acceleration, but will sacrifice

Changing sprocket diameter can present problems – sprocket clearance on the front limits how big you can go, and you want to avoid going too small as the tight turn wears the chain prematurely. Additionally, you can run into problems with the chain slapping the swingarm if you go too small on front and/or rear. This is something you cannot always see when the bike is static, the combination of swing arm movement over the bumps, and acceleration or deceleration cause the chain to tag the top OR bottom of the swingarm.

Changing sprocket sizes may effect chain length. As roughly 1/2 of each sprocket has chain touching it, each tooth added to stock sizes will require approximately 1/2 link of additional chain. Increasing total teeth by one or two teeth can usually be accommodated by moving the rear axle forward slightly and keeping the stock chain length – but if you start changing sprocket sizes more than one or two teeth, you will need to increase chain length. Going up four teeth will require a chain 2 links longer.

630, 530, 525 & 520 chain?

O-Ring, X-Ring, non-O-Ring?

What does it all mean?

Chain comes in a variety of pitches and widths. It is crucial to select the correct chain and sprockets for your bike.

The first number of the chain type designates the chain pitch and represents the distance between each pin in eighths (1/8) of an inch.

630 chain is 3/4″ pitch (or think of it as 6/8″), 530 chain is 5/8″ pitch, and so on – so if you are not sure what size chain you have on your bike, just measure the pin-to-pin distance.

The second two numbers show the width of the roller section of the chain in eighths of an inch – with an assumed decimal point between the numbers. 630 chain is 3/8″ wide and 525 chain is 5/16″ wide (2.5 eighths).

520  =  5/8-inch pitch, 1/4 inch wide
525  =  5/8-inch pitch, 5/16 inch wide
530  =  5/8-inch pitch, 3/8 inch wide
630  =  3/4-inch pitch, 3/8 inch wide

O-Ring vs Non-O-Ring chain

The O ring in modern motorcycle chains protect the chain from moisture and dirt – both of which contribute to rapid chain wear.
The O-Ring style chains now come with a variety of different shaped O-Rings to provide more protection – The following pictures from RK Excel shows the different shape O-Rings used in chains today – the X and W profile O-Rings trap lubricating grease and help provide protection.

However, here are some small disadvantages of the O-Ring chains…

1. The total width of the chain is greater than non-O ring chain – the presence of the O rings spaces out the side plates and requires longer pins – this adds to the weight of the chain and can require spacers to ensure the wider chain clears the engine cases. With a select few models (CB350F, CB500F and CB550F), you cannot use an O-ring chain due to the chain rubbing the transmission cover.

2. The O rings create a small amount of drag on the chain that results in a minor performance loss at the rear wheel. The big advantage of the O ring chain is the greatly improved life of the chain – often doubling or tripling the life of the chain and sprockets over an equivalent non-O ring chain and sprockets. You do still need to use a chain lubricant on the chain. Match the chain lube to the type of chain.

Chain has different tensile rating – this strength rating shows how much force it would take to pull a chain apart – the higher the tensile rating, the stronger the chain.

Motorcycle chain uses an alternating over/under link pattern. Because of this, chain is always sold in even numbers of links.

NOTE: Avoid putting non-motorcycle (industrial) chain on motorcycles, these chains are NOT designed for running at speed and enduring the harsh stresses put on them by a motorcycle.