Gedereit is a known German brand, not in the first or second or third ranks (plutocrtatic bikes and steel custom bikes and then the best bikes for each function) but definitely on the shopping list of the knowledgeable German burger; in short, a well-made middle-class bike, a reliable commuter or tourer (from a Cerman viewpoint -- the obsession of touring or even commuting on near-road bikes is particularly Brtitish and American).
All the same, for a used bike, £800 is a better deal for the seller than the buyer. After Christmas you'll be able to pick up a new Gudereit LC-R (R for Rohloff) in Germany for under €1600.
Right now, here's a new one for €1779/£1447 delivered to your door in the EU, fully equipped with Rohloff, Magura hydraulic brakes, BUMM Cyo lamp, hub dynamo, Tubus Cargo etc, mudguards, Schwalbe Marathon, nothing more to spend, except I don't see a lock.
http://www.afs-guenzburg.de/Artikel_Radsport_Trekkingrad-Gudereit-SX-R-14-Gang-Rohloff-2012.html That was just the first one I happened across. There are probably much better deals to be had, if you want to shop around; try Yatego or
http://www.zapmeta.de/wsde/aw2w33039/gudereit%20lcr%20rohloff/***
I looked into Gudereit a few years ago. I'd suggest them to someone on a tight budget and not too discriminating about the ride of an aluminium frame.
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But your average reader of this board, who hopes one day to own a Thorn, probably wants a steel bike, and something a little more sporting, and by shopping right can make a step up to one of the VSF steel models for around ten per cent more than a Gudereit. A VSF T900 is an aspirational bike for many, a first class piece of machinery. Okay, it isn't a Thorn, but then it isn't anywhere near a specced-up Thorn's money either. I'd have no hesitation in recommending a VSF to an experienced and discriminating cyclist still wending his way to the cycling peaks.
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Just my opinion, of course.
Andre Jute