Top London Mechanics

Slightly OT but what do you mean by this? I mean, if the front mech shifts crisply and everything works, does it matter if the tension is "off" (and define "off" anyway?)

(I'm one of those who does 99% of the work on our bikes, but this one confused me. Clearly something I need to learn to do the other 1%).

Off is too tight or too slack, both can present problems when shifting under load or across drive.