I've come up with a design for a trigger shifter adaptor for my speedhub. It takes the place of the external mech box (it's about the same size and weight), but allows you to run the cables to any type of existing shifters.
I think it very unlikely that anyone would want to replace Rohloff's EX box (or buy the expensive conversion kit to an EX box only to discard the most expensive part of the kit!) unless Rohloff blesses your modification and specifically says it doesn't invalidate their warranty. Furthermore, anyone who has used the rotary control and become used to its straighthrough instant multi-gear changes, as other posters have mentioned, will not want your bright idea because it requires repeated clicking. But see below the next par...
That essentially limits you to the niche market of folk who insist on drop bars, who have problems fitting the rotary control. And even for them there are cheap solution. All your concept really offers them is in fact the facility not to take their hand off the handlebar to change gear...
However, the Rohloff rotary control isn't the nicest control in the business. Shimano's Nexus rotary controls are much smoother. Shimano has already shown the way with the Di2 electronic shift, first as a complete auto job in the Cyber Nexus for comfort bikes --
http://www.audio-talk.co.uk/fiultra/BICYCLE%20Trek%20Navigator%20L700%20Smover.html -- and then in the manually controlled electronically assisted cut-down Dura-Ace version.
Let me suggest to you that instead of a mechanical trigger, you work on using a pair of stepper motors, or one bidirectional stepper motor, to operate the cables that every Rohloff owner already has installed on his bike. That gets around the problem of not working with both the internal and external shifting mechanisms, and also around the problem of discarding the EX klickbox (a very big psychological barrier to anyone who just lashed out serious money for the best German engineering). The electronic control would be a tumble switch or two buttons and can be mounted anywhere convenient. The stepper motor can be battery-operated like Shimano's Dura-Ace implementation of the Di2 concept or by a hub dynamo as in the Cyber Nexus full auto implementation of the Di2 concept; I suspect that most of the people who will splash out on a better shift will either already have hub dynamoes or just need an excuse to fit them.
Even so, I don't think there is a huge market. In my first week with the Rohloff rotary control, I might have paid thirty or forty pounds for a better shift, but now mine has been run in and is much smoother, or I've become used to it, and I won't spend even that much on an added complication. (And I'm the guy who bought a complete Cyber Nexus setup... But that entire setup, including superb electronically controlled adaptive suspension, only cost 340 Euro more than buying the same bike without the electronic gubbins) STG120 is an eighth of what someone has paid for his Rohloff box. You can get a really good wheel with hub dynamo and a superior BUMM lamp set to go with it for that. It's too much for a mere gearchanging convenience.
I might add that, were I still doing this sort of consulting, I would advise you to consider the likely limitations of the market, and *raise* your price so that your margin will cover quite a bit of advertising to reach a much smaller but well-endowed market, in much the same way that Shimano sells the Dura-Ace cut down version of Di2 for several multiples of the original, much more useful Cyber Nexus version. That is, give customers a feeling of joining an elite group, rather than merely buying utility.
I wish you luck.
Andre Jute
