I'm researching Thorn options for a second bike to carry lightweight camping equipment - say 15kgs in total - for trips to France next spring.
I also want wider tyres, better brakes and a hub dynamo.
Can those experienced Sherpa (26") and Club Tour (700C) riders please advise me on their experiences and the relative advantages / disadvantages of each model particularly for camping touring?
From the Thorn brochure, the recommended load carrying capacities for the Sherpa and Club Tour are very similar for on-road use:
28kgs max in front and rear panniers or 18kgs max in rear panniers only for the Club Tour for "relaxed, sweet handling"
This varies with frame size for the Sherpa, 28kgs max in front and rear panniers or 20kgs max in rear panniers only for a frame in the 565S size, which is probably about the size you would want.
Sherpa is quoted as having higher recommended load carrying capacities than the Club Tour for off-road use.
So as far as load carrying capacity is concerned either Sherpa and Club Tour would be good.
If you want wide tyres, assuming mudguards Sherpa will go to 50mm, Club Tour less, it depends on the fork you choose but 40mm seems to be the maximum. I like the 50mm Supremes on my Raven Tour (Rohloff equivalent of a Sherpa), I noticed no great difference in rolling resistance between 40mm and 50mm (tried both widths), but 50mm are more comfortable and I believe they cope better than the narrower tyres when loaded. I also like to use the occasional track or path, where wide tyres are even more useful. That said, in the past I have done a fair amount of winter cycle camping on my old Woodrup lightweight (I'd rate that as in between Audax and Club Tour) with 32 mm tyres.
If by better brakes you mean discs, the Club Tour can have these and AFAIK the Sherpa can't. Personally I find V-brakes perfectly adequate, even down steep hills in the wet with a full camping load.
Either model can have a hub dynamo, but if using a front disc brake there is less choice and generally only in the more expensive models. I have Shimano, SP and SON dynohubs on my bikes, all have worked well, I have noticed no significant difference in efficiency between brands and I have had zero problems so far. Shimano is the cheapest, in this brand I prefer the mid-range DH-3N72 which has a steel axle.
For a camping load, whatever bike you choose I would recommend a good quality tubular steel rack for stiffness. Thorn's own brand rack is very solid, with a very long platform, useful for strapping bulky things on (tent, sleeping mat, 10 litre waterbag for wild camping). Tubus do a (more expensive) stainless steel rack (Cosmo model) that has no paint to rub off and cause rust spots, and a much shorter platform (so IMO les suitable for camping). I have a Cosmo on my old utility bike, where it has performed very well with heavy (non-camping) loads up to about 44kg. I reckon the Tubus isn't quite as strong as the Thorn rack, but more than adequate for 15kg.
With 15kg, you might not need front and rear panniers, unless you like to have a fair amount of spare capacity for food, etc. The only front rack I would recommend is Thorn's own brand low loader. This rack seems very rigid, I have even tried it with a pair of full Ortleib rear panniers and my Raven Tour still seemed to perform OK (but absolutely not recommended as this amount of luggage overloads the forks, except perhaps on a Nomad expedition bike).