Originally Posted by tenorjazz
You have a support for a chain tensioner, I personal would use him.
As already mentioned without chain tensioner and with the big rear sprocket and the "hughe distance between rocker axis and front sprocket axis, there is no chance to get it work proper.
We don't have to forget the rear shock and the differences of chain
lenght you need when the rear shock is completly submerged.
Also the older bikes one had one, like this bike here:
It is maybe not original but it is a invention in matter of technic, maintance, durability and comfort.
The small version would be the installation of a chain roller on that pin like it is used on MX bikes.
By the way, the chain looks small too, surly not an 520?