Your bike’s final drive was designed by some really smart engineers to deliver serious performance while also staying composed, predictable and reliable through the constantly changing demands of everyday riding. And it was designed to do that for thousands and thousands of trouble-free miles provided that we, as riders, do our part. Performing simple routine chain tension checks and adjustments goes miles—quite literally—in assuring our bikes will perform at their best mile after mile and year after year.
Become a slacker
The amount of “slack” (up-and-down movement) of your bike’s final-drive chain determines how smoothly and efficiently power will be delivered to the rear wheel. A properly adjusted chain assures the chain links are aligned with the gear teeth of the front and rear sprockets, distributing power evenly and, at the same time, minimizing wear. Becoming a regular slack-checker is an ideal way to keep your bike performing at its best.
Pick the right spot
It’s important to select the appropriate spot along the length of the chain to determine proper adjustment. The measurement point will typically be where the chain has the greatest amount of deflection, commonly the midpoint between the front and rear sprocket. Check your bike’s owner’s manual to know just where to take the measurement on your bike. Note that some street bikes have a “window” with hash marks to make measurement easier.
Make sure things measure up. And down.
What you’re measuring is the distance the chain deflects upward and downward. The chain will naturally sag thanks to the forces of gravity. At the designated spot along the chain, push the chain upward and measure the distance between the upper and lower limits of movement. Typically, that distance is about 1 inch, but be sure to check your bike’s owner’s manual for exact specifications.
Move your axle.
Adjusting chain tension is straightforward. On each side of the rear swingarm you’ll find a long adjusting bolt or cam-shaped adjuster. Regardless of the design, the adjusters do the same thing: they shift the rear axle forward or rearward slightly (after you’ve loosened to axle nut, of course). To tighten the chain and reduce up and down deflection, you’ll be moving the axle rearward. To loosen the chain and increase deflection, the axle is moved forward. Make small adjustments and be sure to adjust each side evenly to keep everything aligned.
Too loose. Too tight. Just right!
It can be tempting to make the chain nice and snug in the interest of extending the time between chain adjustments. But don’t be fooled. A tight chain will cause the system to bind up, robbing power and creating strain on the final drive components, ultimately accelerating chain and sprocket wear and actually reducing the time between required adjustments.
While a looser chain will minimize strain, if it’s too loose the chain can “slap” against other components, create increased driveline lash (delayed and abrupt response to acceleration and deceleration), and contribute to rapid wear of the sprocket teeth. The ideal adjustment is a “relaxed” chain that is neither tight nor loose. Again, refer to your bike’s owner’s manual.
Making certain your bike’s chain is well-adjusted will deliver maximum performance and miles and miles of reliable service. All it takes on your part are simple routine checks of chain tension and periodic chain adjustments. Now you know how.
Have additional questions? Don’t hesitate to reach out to us directly to get answers from the chain and sprocket experts at Sunstar.