My chain currently has 40 mm of slack which is to much as far as I know, so I need to adjust the tension. What I am wondering is if the back wheel has to be off the ground or if this can be done with the back wheel on the ground? As I don't have a centre stand. Also I don't have a torque wrench or know the amount that is meant to be applied as I don't have an owners manual and can't find one online, will this be an issue? Yes, I konw there have been previous threads on this, and I have looked at them but haven't been able to find an answer to my question.