Symptom:

The ELF has multiple chains (2 or 3 depending on the age of your ELF) - over time they stretch and adjustments need to be done to take up the slack. If the pedal chain is visually loose or tends to hop off of the guide wheels (aka idler pulleys or tensioner wheels) from time to time it should be tightened.

Solution:

• Start from the front, move things backward until chains are tight. If the rear wheel moves back too far, remove links.
• Tighten all three chains:
  • start with the chain from the front peddles to the NuVinci. You adjust this by sliding the NuVinci towards the back.
  • Then tighten the chain from the NuVinci to the back tire. This is done by sliding the back tire towards the back.
  • The last chain to tighten is the one from the motor to the back tire. Tighten this chain by sliding the motor forward.
    

• Tighten the 2-chain models:
  • slide the motor backward to slack that chain, slide the rear wheel backward to tighten the long chain, slide the motor forward to tighten the short chain.

• For a standard drive.
1. loosen the 6 bolts on the slider that holds the electric motor and the 6 on the rear wheel
2. pull the rear wheel backward until chain snug, tighten bolts. It helps to have a friend pull while you tighten, but it doesn't have to be super tight.
3. slide motor forward until that chain is tight, tighten bolts.

• For Updrive and NuVinci CVT

    This can all be done without having to lift the ELF. It is a three step process.

1. loosen the bolts on the slide rail mounting brackets for the NuVinci, motor and back tire from both the left and right sides. You will need a 10mm open wrench and socket for this. Tighten the chain from the foot peddles to the NuVinci by sliding the mounting bracket for the NuVinci towards the back of the ELF. I slightly tightened one of the bolts on the bracket to hold it in place and then very gently tapped the edge of the bracket with a hammer to tighten the chain. You want to tap both the right and left side evenly in order to tighten the chain. Once the chain is somewhat tight (you want a little slop in the chain) the bracket can now be tightened.
2. The next step is to tighten the back wheel chain for the pedal. Under the ELF there are two chain tensioners. One for the peddle chain from the NuVinci and one from the motor to the back tire. Slide the chains off from the tensioners. Slightly tighten one of the bolts on the slide rail bracket on the back tire. Very gently tap both sides of the bracket towards the back of the ELF until the left side pedal chain is slightly tight. You don’t want it too tight since it still needs to be placed back onto the chain tensioner. Tighten the bolts on the slide bracket for the back tire.
3. The last step is to tighten the motor chain. Once again slightly tighten one of the bolts for the motor slide rail bracket. Tap both the left and right side of the motor bracket forward until the motor chain is at the same tension as the pedal chain from the NuVinci to the back tire. Now tighten all of the bolts for the motor slide rail bracket. Slip the motor and peddle chains back on to the chain tensioners. Your Done!

Chain Advice

Chain FAQs:

• The chain tensioners use 608rs bearings and can be replaced if they start squeaking loudly.
• Don’t forget to oil the chains!
• If you need to replace your chain Mark bought on Amazon: KMC Z50 Bicycle Chain (6-7-Speed, 1/2 x 3/32-Inch, 116L, Dark Silver/Brown. Edward bought a kmc z510hx chain.
• The electric drive uses a Patterson heavy duty chain. Same cog gaps, so you can use a standard chain in a pinch, but the electric motor puts out a lot more than a human possibly could, so you'll trash a regular chain in a hurry. You could use a Patterson for all of it, for sure, but that's heavy, expensive, and less efficient.

Helpful Links:

• Unseated Chain (via Organic Transit)