They should give a torque wrench away with a Rohloff hub gearbox

[macspud]

The Rohloff manual has a full listing of torque values in the text for common user-serviceable items (as on page 81-82 for the EX shift-box) and also on page 124 of this download:
https://www.rohloff.de/fileadmin/user_upload/Manual_2017_11_web_En.pdf

Twist shifter clamp torque calls for lightly greasing the mounting screws and then torquing them to 1Nm/8in.lbs. (page 73 in the PDF at the link above).

Best,

Dan.

2 2.5mm allen key Clamp bolts: M5 x 8  (tightening torque: 1Nm / 8 in.lbs.) old version 8200  or 2 Torx TX20 wrench Clamp bolts: M3 x12  (2Nm/16in-lbs.) new version 8206

In High Moors Drifter's case the new version 8206. When fitting, both clamp screws (M3x12 - Torx TX20) should be lightly fitted so that the gap between both clamp elements is identical. Insert the screws using the pressure of just two fingers on the TX20 tool. Finally tighten each screw by max. 2Nm (1/2 rotation). The Twist Shifter should now be tightly secured to the handlebars.

Over tightening of the Clamp Screws can cause damage to both Twist Shifter and/or handlebars.

Covered here https://www.rohloff.de/fileadmin/user_upload/Manual_2017_11_web_En.pdf on page 141

[Danneaux]

Yep!

Nice update. 

Best,

Dan.

[Dave Whittle Thorn Workshop]

I've never used a torque wrench to install one, just gradually increase the tension until it cant be rotated round the bar with normal hand force. I might use one if I was installing on carbon, but we don't see much of that here.