Quote Originally Posted by m_c View Post
You don't have to retension timing belts on cars, and the latest ones last 150,000miles or 10 years with no maintenance.
And given quite a few run with fixed tensioners, stretch isn't a concern.

Every car i have had has always got some form of tensioner on the timing belt, in most cases its a idler pulley under spring tension (auto belt tensioner).

You could argue this just keeps the belt tight against the pulleys, but i have noticed a slight difference in length when i have changed them in the past. But whether you would get this much on a router to cause major problems, who knows.