Motorcycle Chain Sizes: 428, 520, 525 and 530, Link Count and Gearing

In a motorcycle chain size code, the first digit gives the pitch and the last two the inner width: 4xx chains have a 12.7 mm (1/2 in) pitch and 5xx chains a 15.875 mm (5/8 in) pitch. 520, 525 and 530 share the same pitch but differ in width; the chain must match both sprockets.

How to read a chain code

Code	Pitch	Width	Typical use
415 / 420	12.7 mm	Narrow	Mopeds and small bikes
428	12.7 mm	Medium	Many 125–250 cc motorcycles
520	15.875 mm	1/4 in (6.35 mm)	250–600 cc bikes, off-road and race conversions
525	15.875 mm	5/16 in (7.94 mm)	Mid and large road bikes
530	15.875 mm	3/8 in (9.53 mm)	Large and heavy motorcycles

An “H” at the end (e.g. 428H) denotes a heavy-duty version with thicker plates in the same size. The table shows general trends; your bike's chain size is in the manual or stamped on the old chain's plates.

O-ring, X-ring and standard chains

• Standard (non-O-ring): economical with low friction; needs frequent lubrication and adjustment.
• O-ring: rubber rings keep grease between pin and bushing; lasts longer.
• X-ring / Z-ring: a different ring profile with lower friction than O-ring and longer life.

Use seal-safe cleaners and lubes on O-ring and X-ring chains. Cleaning and slack adjustment are explained step by step in our chain and sprocket guide.

Working out the link count

Link count depends on the sprocket sizes and the distance between axle centres. The reliable methods are:

1. Count the links on the old chain (including the master link).
2. Check the link count in the manual (e.g. 120L).
3. If you changed sprockets, find the required count with our chain length calculator.

Chains are usually sold long and shortened with a chain breaker. The link count should always be even; an odd count needs a half link, which isn't recommended.

Master link: clip or rivet?

Type	Advantage	Watch out
Clip	No special tool needed	The clip's open end must face away from the direction of travel
Rivet	More secure on powerful bikes	Needs a rivet tool and the correct rivet diameter

Changing the gearing

The final drive ratio is the rear sprocket's tooth count divided by the front's. A 14-tooth front and 42-tooth rear give a ratio of 3.0.

• One tooth fewer at the front (or 2–3 more at the rear) gives stronger acceleration and a lower speed at the same rpm.
• One tooth more at the front raises top speed and touring comfort and softens take-off.
• Changing the ratio can make the speedometer read differently and change the chain length.

Compare how different sprocket combinations affect speed and rpm with our gear ratio calculator.

Replace the chain with the sprockets

A new chain on worn sprockets stretches quickly, and an old chain ruins new sprockets. Replacing the chain and both sprockets together as a chain and sprocket kit is the most economical and safest option. For a chain or sprocket alone, see the Chains and Sprockets categories.

How to measure chain wear

As a chain wears, play between pins and bushings grows and the chain “stretches”. A practical way to measure it is to check the length of a set number of links with the chain under tension:

1. Rotate the rear wheel to pull the lower run tight.
2. Measure across 20 pins (19 pitches) with a caliper or steel rule.
3. Compare with the theoretical value: 19 pitches are 301.6 mm on a 520 chain and 241.3 mm on a 428.
4. If the reading exceeds the manufacturer's service limit (typically about 1–2% over the theoretical length), replace the chain together with the sprockets.

What is a 520 conversion?

Some riders convert bikes with 525 or 530 chains to a lighter, lower-friction 520 chain. This requires the front and rear sprockets to be 520 size as well. A conversion saves weight and helps acceleration, but chain life can be shorter; on powerful bikes pay attention to the chain's strength rating.

Frequently asked questions

Can I fit a 525 chain instead of a 520?

The pitch is the same but the width differs; a 525 chain won't fit 520 sprockets. Changing chain size means changing both sprockets to the same size (as in a 520 conversion).

When should a chain be replaced?

When the adjusters reach the end of their travel, when the chain can be clearly pulled away from the back of the rear sprocket, when it has tight and loose spots, or when links are seized or rusty.

What if I choose the wrong link count?

A short chain can't be fitted; a long one won't fit within the adjuster range. Find the right count in the manual or with the chain length calculator.

How long does a chain last?

Chain life depends on chain type, engine power, riding style and above all maintenance. An O-ring chain that is regularly cleaned, lubricated and kept at the right slack lasts far longer than a neglected one. Rather than relying on a fixed mileage, check stretch and sprocket wear regularly.