Friction shifter for Rohloff speedhub? This is might be trivial for someone who actually have a one, but after countless hours reading and watching about the Rohloff speedhub I can't answer this question myself.

AFAIK the OEM grip shifter is not the most loved feature of the system. It can't be used with drop handlebars, - as all other grip shifters - it is slippery when wet, and it is not a trigger shifter. So far I have found 23 quirky ways to overcome the handlebar issue, and one trigger shifter review. 

My first idea would be just to use a one-cable (maybe indexed) friction shifter, and some counter pull mechanism on the other end of the cable to replace the second cable. Seeing the how much effort has gone into mounting or replacing the original shifter, there should be something why this won't work.

So why? Why there is no friction shifter available for this hub?
The Rohloff shifting mechanism is designed specifically not to include a spring or other mechanism to move one of the directions. Since it pulls so much cable, it would indeed be difficult to do a single friction shifter. The 2-cable system is feature, not a bug, since Rohloff believes the 2-cable system to be more reliable than one cable + spring. 

They discuss spring mechanisms as prone to failure. I've had a high-end SRAM x.0 derailleur main spring break on me in the middle of a commute (fixed it with a zip tie in the middle of the cassette so I could at least get home with the 3 rings in front as my gears), so I've seen them go myself. The 2-cable system also makes it pretty simple to keep the bike going should one cable fail, since you can shift the bike with a wrench, something that wouldn't be possible if there were a spring trying to return the hub one direction or another (unless that were accounted for in some design).

That said, there is a trigger shifting option (ed. by cinq5) which is using 2 triggers. It's described in a blog post by Cycle Monkey.


  I love my Rohloff but I'm no fan of the grip shifter, only because it
  slips in my greasy hands. If it just had a different texture, I'd be happier. 


Best solution I've seen was to save a few of those giant rubber bands, that are used to tie broccoli in stores, and apply them to the shifter with a cross pattern for an easy friction increase. I need to go visit the produce section myself.