Re: How to make a spring tensioner?
Why do you want one? Spring chain tensioners on motorized bicycles aren't really needed and don't work well because you're dealing with acceleration and deceleration forces. A spring tensioner allows chain slack when you least want it.
The best option is to run without a tensioner but that requires some way to maintain proper chain tension such as horizontal drop outs or shimming the engine to adjust for chain/sprocket wear, sometimes called 'chain stretch'.
If you must use a tensioner the best recomendation is to mount the bracket so it bridges the seat and chain stays. The kit supplied brackets can be made to work but they must be bent/twisted so the wheel will align with the chain centerline. The bracket also must be mounted in such a way as to assure it can not loosen and rotate into the spokes.
There are pages of discussion on chain tensioners here. Just type 'chain tensioner' into our search box and you'll have lots of food for thought on the subject.
If your heart is set on using a spring tensioner there is a member here who manufacturers them and they are offered for sale in our 'Swap & Shop' section.
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