I spent a full weekend trying to figure out why my 1972 Honda CB350 kept skipping teeth on the rear sprocket. The chain looked fine to the eye. It had the right tension, no kinks, and I had even measured it with a tape measure. But after a short test ride, I heard that telltale clicking sound. A friend who restores old British bikes told me the problem was almost certainly the drive link count. I did not believe him at first. How could one extra link make that much difference? But he was right.
When I started researching how to get the exact count right, I found that most modern chain tools tell you the pitch and the length in inches, but they do not always help with the precise number of drive links needed for a specific sprocket combination. I needed a reliable reference. That is when I found a page that explained the math clearly and even included a built-in calculator. The page at kakei drive links gave me a simple method to count the links based on the sprocket tooth counts and the wheelbase. It changed how I approach every chain job now.
Why chain fitment is not guesswork
Motorcycle chains do not stretch evenly. Heat, wear, and dirt cause individual links to vary. A chain that looks right when you hold it against the sprockets can have two or three links too many. That extra length lets the chain slap against the swingarm, wear out the chain guide, and eventually damage the countershaft bearing. A friend of mine lost a whole transmission because he guessed the link count by eye. He saved the engine case, but the repair cost more than the bike was worth. I learned from his mistake.
On my CB350, the correct drive link count turned out to be 96 links for the 15/40 sprocket set. But the stock chain spec says 98 links because the factory used a different tooth count. If I had followed the manual blindly, I would have put on a chain that was too long. The bike would have run, but not well. The shifting felt vague. The chain slapped the underside of the swingarm. It was a matter of two links, but those two links made the bike feel like a different machine.
The method that works every time
I now use a simple three-step process. First, I wrap the old chain around the sprockets and mark the master link location with a paint pen. Then I count the number of drive links between the reference mark and the next master link position after the chain is fully seated. Finally, I compare that number to the calculated ideal from the sprocket combination. If you do not have the old chain, you can measure the wheelbase and use the pitch to calculate the count. The key is to do the math on paper, not in your head.
Most garage mechanics stop after step one. They think the old chain length is correct. But old chains wear and the links can actually get longer. The pin-to-pin distance increases slightly over time. You cannot reuse the old length and expect the new chain to fit the same. The new chain will be tighter because it has no wear. That means you need to remove a link or two. Counting the drive links on the new chain before you install it saves you the hassle of taking it off again.
Tools that make the job easier
You do not need a complicated machine to count drive links. A simple ruler with millimeter marks works, but I prefer a small caliper for accuracy. You measure ten links of the new chain, divide by ten, and that gives you the true pitch. Then you multiply by the number of links you need. That gives the total length. But the real challenge is keeping the chain together while you count. I use a piece of wire to hold the master link temporarily. That way I can double-check the count without the chain falling apart.
- Use a paint pen to mark the first and last link of the section you count.
- Write down the number as you go. Do not rely on memory.
- Count twice. A single link mistake can ruin a ride.
- If you use a clip-style master link, always install it with the open end facing the direction of travel.
- Check that the chain aligns with the sprocket centerlines before you tighten the axle.
- Spin the rear wheel a few times by hand to see if the chain runs smooth.