Hello, Bit confused on checking the chain tension. The book says to pull then release the chain at the tightest centre point (so I assume this is just to release any tension) then measure the gap between the swing arm and chain. I assume this is as the red line in the picture. It says this should be about 61mm. When I do this on mine the chain hardly moves at all and the gap is about 30mm. I asked a garage and he said the chain was fine. Am I doing something wrong? and why do you measure it this way, all other bikes I've had you measure the amount of slack/movement of the chain.
