This is similar to what they use at the factory to set the belt tension:
http://www.gates.com/products/industrial...and-accessories
It does seem to result in quite a tight belt at 50Hz and I run mine slacker than this, about 20mm deflection in the belt.


2021 M3W
2013 M3W - Sold
1971 4/4 2 Seater
1934 Sports