Just to add to zzxxyy's post, SRAM sprockets for the S7 are reversible, as are most chainrings for single speed/hub gears. So with a perfect chainline and the fact that you effectively get to use them twice, I dare say they will last longer than a cassette.

This discussion is really getting nowhere. One guy thinks he has the definitive word on the hub gear/derailler debate, but despite all his ramblings he hasn't convonced me of anything. The main reason for this is that he doesn't even have any first hand experience! I've been using a SRAM S7 for commuting all winter here in Scotland where it rains a LOT and its been completely trouble free and it IS easier to clean than a derailler system. Now being easier to clean may not matter if you have an outhouse or a garage where you can clean your bike, but I live in a small apartment and have to strip and clean my bike indoors (the alternative being out on a busy street) so I appreciate the ease of cleaning.

I think its necessary to draw some distinction between the Shimano hub gear and offerings frrom SRAM and Rohloff. With few exceptions the persieved "problems" alluded to at length already have been with Shimano hubs and not the SRAM hubs (and defintely not the Rohloff). Most of the arguments by the aforementioned "expert" do not apply to the Rohloff (durability and gear range seem to be the main issues). I've been following the fortunes of a number of expeditions around the world where people were using Rohloffs and though they weren't always problem free, they convinced me that this hub IS superior to a derailler system. Initially I was extremely sceptical, but the Rohloff has proved itself to be a superb piece of German engineering that is excellent for its intended purpose.

I recently did a bit of loaded touring with an S7 and I believe that with the right choice of chainring and sprocket you do JUST get a big enough range (I had a 32 chainring with a 22 sprocket and could still spin at 35km/h in top gear which is enough for touring IMO). So in reply to huhenio, yes I think a hub gear would be suitable for your wife, but the general concensus here in the UK is that the SRAM S7 is functionally better than the shimano hubs and more durable.

In reply to Inetersted - your views have been expressed and you should now leave people to decide for themselves what is best for them.