It depends on many factors, terrain, fitness, surface, speed you'd want to travel etc.
Tow paths are pretty flat. 2 to 1 is a good start on a MTB but you doing the same journey over and over gives you a perfect choice.
Make a concious effort to keep a current bike in one gear only that suits you, if it doesn't try the same journey in a different gear. Once you've found an ideal count the teeth and use that.
I found that REALLY hard. I kept forgetting and changing gear
I've only just thought about it, but what about taping up your shifters so you can't easily change gear. I think that would help to really simulate SS (if you're as undisciplined as I am).
I just went for it, and although I got the gear wrong on my first attempt, it was MUCH easier than I thought it would be.
Ahh, but the dice cannot read their own spotshttp://www.bryankidd.co.ukLet me know what you think of my Tomac screenprints http://www.retrobike.co.uk/forum/viewto ... p;t=288972