It's recommended that you measure the chaincase chain tension on your Timbersled snow bike system each time the chain is lubricated. Do not over-tension the chain. Improper chain tension can cause excessive wear to the chain and the tension roller bolt. You should inspect the chain for wear and tension as part of the pre-ride inspection of your Timbersled ARO, Timbersled RIOT or Timbersled 120 SX.
Measuring Chaincase Chain Tension
To measure the chaincase chain's tension, do the following:
1. Remove the fasteners from the chaincase cover.
2. Position a ruler behind or in front of the right cord of the chain, halfway between the drive shaft sprocket (4) and the jack shaft sprocket (2). This is where the chain's displacement should be measured. Position and steady the ruler so it does not move as chain displacement is measured.
3. Choose a single chain link pin close to the ruler to use as a reference point for measuring chain displacement. Push the chain's right cord to the left near the chosen link pin using one finger. Line up the 1-inch mark on the ruler with the center of the chosen chain pin.
4. Then, without moving the ruler, push the chain's right cord to the right with one finger in the same location and count the number of 1/8-inch marks between the 1-inch mark and the new position of the chosen chain pin.
If the chain is properly tensioned, there should be between 1/2-inch and 3/4-inch between the 1-inch mark (the position of the chosen chain pin when pressed to the left) and the current position of the chosen chain pin (when pressed to the right). This is the chaincase chain's displacement measurement (1). If the chain's displacement measurement is less than 1/2-inch or more than 3/4-inch, the chain tension needs to be adjusted.
Adjusting Chaincase Chain Tension
To adjust the chaincase chain's tension, do the following:
1. Loosen the tension roller bolt (3).
2. Adjust the chain tension as needed by pushing the roller bolt (3) toward the chain to increase tension or away from the chain to lessen tension.
3. Then tighten the tension roller bolt (3) firmly once again.
4. Measure the chaincase chain's displacement (1) once more to ensure proper adjustment.
Chain Inspection
Regular Timbersled chaincase chain inspection is important. A broken chain can cause damage to the host bike. Chains need to be regularly inspected for signs of wear, damaged and stretching.
A chaincase chain that has stretched 1 percent or more of its length is worn out and will need to be replaced. Also note that a chain with 1,000 miles or 75 hours of use also will need to be replaced.
To measure chain stretch, perform the following procedure.
1. To determine whether the chain has stretched 1 percent or more, first ensure the chain is taut along the area you plan to measure.
Timbersled RIOT and ARO snow bikes are equipped with 520 chaincase chains which have a pitch of 5/8 inches or 0.625 inches. A chain's pitch is the length of a single link, which is measured from the center of one pin to the center of the next pin, as shown below (A).
2. Mark out the number of links to measure. For the chaincase chain, it's 17. To mark this number of links, begin by marking the first pin (3 in the photo above) and counting forward the same number of pins. The number of pins counted should equal the number of links to measure. Finish by marking the final pin. The above image shows the first and final pin marked.
| Number of Links to Measure | Expected Length | Expected Length + 1% | Acceptable Length Range |
| 17 (mark first and last pin) | 10.625 or 10-5/8 inches (17 x 0.625 = 10.625) | 10.731 inches or slightly less than 10-3/4 inches |
Between 10.625 and 10.731 inches |
3. Then measure the counted number of links by measuring from the center of the first pin (3) to the center of the final pin (4). This measurement should equal a length somewhere within the acceptable length range of 15 and 15.15 inches.
4. If the length of the counted chain links equals or exceeds the expected length plus 1 percent (for the drive chain, this is 15.15 inches), the chain is worn out and must be replaced. If the length of the chain is less than the expected length plus 1 percent (in other words, it is within the acceptable length range), the chain does not need to be replaced at this time.
For more information, see your authorized Timbersled Dealer. To find a dealer near you, use the Dealer Locator.
Maintenance tips, procedures and specifications can be found in your Owner's Manual.
To find diagrams and replacement part numbers, use the online parts catalog.
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