Anyone with a Rohloff bike -- and I specifically include even cyclists of vast experience -- should have a low-range torque wrench because the Rohloff fastening ratings are too low to distinguish by fingerspitzengefuehl, and use it everywhere on the bike because the general trend, except for around and between the pedals but especially for ever-more-expensive components, is for lower tightening torque. A decent quality of 1/4in drive torque wrench of which I and others on this board have experience is the BBB BTL-73, which covers 2-14Nm and is widely available for about fifty quid with a travel case to house the bits. Note that this is in fact a BBB-branded generic torque wrench easily found branded by others at a considerable saving. This one is from X-Tools and sold by Wiggle for a third less:
This BBB TL-73 torque wrench, and its generic siblings under other brands, has been found to give consistent service by many cyclists; I've had one for years, buying it from a bike shop's worktable out back when they didn't have a new one in stock for me; when I checked a month or so later, I discovered they had replaced it with the same. Good enough for professionals is good enough for me.
SJS has several beautiful torque wrenches at
https://www.sjscycles.co.uk/search/?term=torque%20wrenchbut at the lower-price end of the wide-range torque wrenches they stock the M-Part appears to be a relative (maybe better?) of our generic, widely applauded, torque wrench above.
https://www.sjscycles.co.uk/tools/mpart-torque-wrench/Whichever set you buy, you will have to buy additional bits to make up the following set, some of them essential to the needs of the Rohloff HGB:
Hex 2mm, 2.5, 3, 4, 5, 6 and possibly 8 or 10mm
Torx T20 for the Rohloff
Phillips No 2 (or whatever is required by any crosshead screws on your bike, which you should anyway replace with hex head socket screws)
Socket 8mm for changing gears if you have the EXT version of the Rohloff
Extension bar to use where you don't have clearance for the ratchet head
In addition you will need, though less urgently, an automobile type torque wrench for higher settings, to give reliable readings in the middle of its range up to about 35-40Nm. "Less urgently" than the smaller torque wrench because there's generally a fair bit of breathing space around the higher settings, and you can usually just torque up the crank bolts, for instance, by blocking one pedal against a lamppost and standing up on the spanner attached to the other-side crank bolt, and that will be around 33Nm. (Not exactly rocket science engineering but it worked for generations of cyclists and LBSs who didn't even know what a torque wrench was.) This exception doesn't apply to carbon bikes, of course. Mine is a standard automobile tool left over from my hot-rodding days. You won't be carrying this one on the bike, so it doesn't matter if it weighs a lot.
I also have a Park Tools swing pointer (called a "beam") torque wrench, no longer made, but an amazingly accurate tool, and it has the huge advantage, at the higher fastening torques, of a handle long enough to do high-torque tightening job right without straining your back, and the readings are quick and easy in whatever tightening measure you need, without the need for mental arithmetic because the scale is universal and seen all at once. If you can get a beam torque wrench in new old stock (NOS) or that hasn't been abused too much, you can buy it and calibrate it against a mate's fancier torque wrench to make up a table of adjustments to readings if necessary; very likely not required as these things last an impressively long time.
If anyone else has a fave torque wrench, please do mention it.
