How tight your chain should be

[cloakedvillain]

Many new builders struggle with chain tension. Here is an illustration that should help and where I got it from. https://www.cisco-eagle.com/vector/504/adjusting-the-drive-chain

 

[DieselTech]

Till it sounds like the banjo on deliverance.!!!

 

[DAMIEN1307]

Till it sounds like the banjo on deliverance.!!!

 

[darwin]

Old rule for M/C's is 1/2 to 1in of total movement up/down measured in the middle of the return loop. That has always served MC riders well for chain longevity. Too tight = friction and premature wear. Too loose chain can bind up in the drive sprocket case causing you to have a really bad day, skipping sprockets.

 

[DAMIEN1307]

Old rule for M/C's is 1/2 to 1in of total movement up/down measured in the middle of the return loop. That has always served MC riders well for chain longevity. Too tight = friction and premature wear. Too loose chain can bind up in the drive sprocket case causing you to have a really bad day, skipping sprockets.

And also keep in mind with a new chain, as you turn the wheel with new chain on it, you will notice a tight loose, tight loose, situation when you slowly turn the wheel to find the "tight" postions...Just be sure it is not as tight as a banjo string when you hit the really tight zone....lol.

 

[darwin]

Yea, swing-arm movement can affect required chain slack on dirt bikes. Those can be 3 inches or so of play.

 

[markjs]

Old rule for M/C's is 1/2 to 1in of total movement up/down measured in the middle of the return loop. That has always served MC riders well for chain longevity. Too tight = friction and premature wear. Too loose chain can bind up in the drive sprocket case causing you to have a really bad day, skipping sprockets.

That should be about right; also a motorized bicycle, no matter how powerful, is not gonna stretch chain and require near as much adjustment. Should be mostly "set it and forget it" as long as all your bolts stay tight. Should take a long time before it needs much in the way of re-tensioning.

Motorcycles with their swingarms, and much higher torque/horsepower driving them, can wear and stretch much more quickly.

 

[ImpulseRocket]

On a fixed chain drive (no articulation on either sprocket in the system) the general rule of thumb should be 2 to 4% of the center to center distance of the sprockets.

Ex: if your drive and driven sprocket are 24 inches apart, that would make an acceptable slack range of .48 to .96 inches. (Notice how that lines up with Darwins figure? ).

Chain slack should always be set with no droop on the tension side as well (top chain run) and set at the tightest spot in the total length of the chain.

 

[ImpulseRocket]

Motorcycles with their swingarms, and much higher torque/horsepower driving them, can wear and stretch much more quickly

It had nothing to do with the power. It's the suspension geometry. Since the rear axle moves in an arc relative to the swing arm axle, which is also offset from the countershaft center, the chain on a swing arm drive is tightest when all three shaft centers are aligned perfectly. Once it swings past alignment in either direction the chain gets more slack.

Dirt bikes have a lot of suspension travel, so in order to keep the chain tension correct at the tightest point in the travel, the slack spec at full droop is much larger since.the rear sprocket is closer to the countershaft due to the arc of travel.

On my dual sport, they state the slack spec as 15mm at the tightest point of the chain with all three shafts in alignment. At full droop, this makes my chain slack 40mm.

A lot of people also confuse the concept of chain "stretch" with the idea that the metal links of the chain are literally elongating. That is not what is happening. Chain "stretch" is caused by roller bushing and pin wear. The pins move more within the rollers, which allows the distance between the rollers of inner and outer links to get closer or farther apart. The pin center to center on each link is the same. If the pin center to center changes on a single link plate, it has suffered a tensilary failure.

 

[darwin]

It had nothing to do with the power. It's the suspension geometry. Since the rear axle moves in an arc relative to the swing arm axle, which is also offset from the countershaft center, the chain on a swing arm drive is tightest when all three shaft centers are aligned perfectly. Once it swings past alignment in either direction the chain gets more slack.

Dirt bikes have a lot of suspension travel, so in order to keep the chain tension correct at the tightest point in the travel, the slack spec at full droop is much larger since.the rear sprocket is closer to the countershaft due to the arc of travel.

On my dual sport, they state the slack spec as 15mm at the tightest point of the chain with all three shafts in alignment. At full droop, this makes my chain slack 40mm.

A lot of people also confuse the concept of chain "stretch" with the idea that the metal links of the chain are literally elongating. That is not what is happening. Chain "stretch" is caused by roller bushing and pin wear. The pins move more within the rollers, which allows the distance between the rollers of inner and outer links to get closer or farther apart. The pin center to center on each link is the same. If the pin center to center changes on a single link plate, it has suffered a tensilary failure.

Finally someone who agrees with me, wear not stretch. IR gets a huge BRO HUG!