Torqmetry / Motorcycle Guide
Motorcycle Chain Length Guide
Correct chain length depends on both sprockets, the center-to-center distance between their shafts and your chain pitch. A formula helps estimate the link count before final fitting.
Try the Chain Length Calculator →The essentials
- Chains described as 520, 525 and 530 generally share a 5/8-inch (15.875 mm) pitch, but differ in width and compatibility.
- Most conventional motorcycle drive chains use an even number of pitches with the correct connecting link.
- Calculated link count is a starting point, not a substitute for axle-adjuster travel, suspension clearance or manufacturer specifications.
Step-by-step
- 1
Identify your chain specification
Read the chain marking and the bike manual. Confirm pitch and width are compatible with both sprockets.
- 2
Count sprocket teeth
Record teeth on the front and rear sprockets. Changes to either sprocket can change required chain length.
- 3
Measure shaft center distance
Measure from the front sprocket shaft center to the rear axle center in the intended adjustment position.
- 4
Calculate, then verify fit
Use the chain-length calculator to estimate pitches and round as appropriate for your chain. Check axle position, suspension travel and required slack before installation.
Understanding the calculation
The chain length formula accounts for the wrap around both sprockets and the two straight runs between them. The number of links is: L = 2C/P + (N+n)/2 + ((N−n)/(2π))² × P/C, where C is the centre distance between sprockets, P is the chain pitch, N is the rear sprocket tooth count, and n is the front sprocket tooth count.
The result is rounded up to the next even number because a chain must have an even count of links to connect with a master link (an odd count would require a half-link). Always verify against the manufacturer recommendation and leave enough slack for suspension travel.
Example: 520 chain with 16T front and 45T rear
- 1. Chain pitch (520): 15.875 mm (5/8 inch)
- 2. Front sprocket (n): 16 teeth
- 3. Rear sprocket (N): 45 teeth
- 4. Centre distance (C): 340 mm
- 5. 2C/P = 2 × 340 / 15.875 = 42.83
- 6. (N+n)/2 = (45 + 16) / 2 = 30.5
- 7. ((N−n)/(2π))² × P/C = ((29)/(6.283))² × 15.875/340 = 21.3 × 0.0467 = 0.99
- 8. L = 42.83 + 30.5 + 0.99 = 74.32, rounded up to next even = 76 links
You need a 76-link chain (round to the nearest even number)
Frequently Asked Questions
What chain pitch do I need?
Chain pitch is determined by the chain type: 420 = 12.7 mm (1/2 in), 520 = 15.875 mm (5/8 in), 525 = 15.875 mm (5/8 in, wider), 530 = 15.875 mm (5/8 in, wider still). Check your owner manual or the side of your existing chain plates for the size stamp.
Why must the link count be an even number?
A roller chain is assembled from inner and outer links that alternate. To close the chain with a standard master link you need an even number of links. An odd count would require a special half-link, which is weaker and not recommended for most street bikes.
How do I measure the centre distance between sprockets?
Measure from the centre of the front sprocket to the centre of the rear sprocket with the wheel at its intended position. Account for chain slack — typically 25-35 mm of vertical play in the middle of the lower run for street bikes.
Can I use a longer chain than calculated?
You can use a longer chain and remove extra links, but you should never use a shorter chain than required. If your calculated length is 76 links and you have an 80-link chain, remove 4 links with a chain breaker to get the correct length.