[Dukedesmo]

And standard chain length for 15/39 is 98 links, you can fit 100 but the wheel will need to be fully back in the swingarm to get the tension and, on mine at least this meant the hugger was then too close to the tyre at the rear.

I found this out because I originally had 15/41 which needed a longer chain but then decided 15/39 suited me better and I ran with the longer chain for a while.