We are often asked about how tight should Miragedrive chains be. Its a good question because if the chains are too loose there is a possibility of damaging sprocket teeth and if they are too tight performance will be impaired. MD180 users should be particularly mindful of not over-tightening the chains, especially the rear one.
To make sure you don't over-tighten the chains, push the pedal arms back and forth with your hands. If you are feeling resistance, it's likely the chains and or idler cable are too tight. Back off the nuts just a bit and try it again. A good quick way to find out if the chains are too loose is to hold each pedal crank in each hand and try and pull them apart. If there is a lot of sloppy movement, chains and idler cable are likely too loose.
Factory built drives are usually spot on out of the packet, so check this when you buy your kayak so you can get a feel for how tight they should be. The front chain is marginally tighter than the rear chain (more important for MD180 drives). Check chain tension regularly. If a particular chain or cable tends to become loose on a recurring basis, the 1/4" nylock nuts securing them might need to be replaced.
Each chain and cable should be somewhat taught, but not over-tightened. Check how much sideways free play you have in the chains where the cable meets the swage (example above). Anything from 2 to 3mm in sideways play is about right for the front chain, 3-4mm for the rear chain. Any less and they are probably too tight, any more and they are probably too loose. Adjust fin tension by turning the 1/4" nylock nuts that secure the chains and to the drum. If a particular chain or cable tends to become loose on a recurring basis, the 1/4" nylock nuts securing them might need to be replaced.