To put it simply

a) Ribble 7005 alloy audax with 10sp Tiagra £700

b) Planet X Kaffenbach with Tiagra and road discs £800

c) Ribble 365 in carbon with Tiagra for £940

Full and proper mudguards are my priority
28mm tyres mandatory

Id be happy with all of the above (plus the steel Ribble that splits them)

The question is at what point does the law of diminishing returns start to apply to winter snotters?

COI: like steel, like discs, dont like alloy buzz

Cheers

I didnt like my kaff at all, partly sizing, partly just felt dead and noodly.

Love my px sl team.. fast, light, zingy, not harsh at all.

Pick the one with geometry most similar to your summer bike. My winter geared bike is my race bike with SKS raceblade long mudguards. I have been amazed at these mudguards compared with some others (crud and normal raceblades, P35 chromplastics). They will take 25c tyres which feel fine to me.

The blue ribble alloy is very popular at our club. I however, like steel bikes if the steel is of good quality, and the summer bike will feel much nicer for riding a heavier steel bike all winter. The carbon Ribble isn’t a winter bike. It’s an Audax bike for all year use.

My proper winter bike is a steel fixed wheel Kona Paddy Wagon with P35 mudguards I have upgraded it with carbon forks and custom handmade wheels. Weight is 10 kilos. The geometry is not far off the other road bikes and the handling great. It will take 28c tyres but I don’t bother.

I’ve been wanting a 365 for a while so it gets my vote. It’ll be a fair bit lighter than the other two. That matters to me perhaps not so much for other people.

i can vouch for tiagra being hardwearing, and i have to say that kaffenback looks good . . .
i dont think you would feel short changed buying any of the above bikes, but i do agree ^^^, geometry/fit is the most important thing.

buy a frame and fork and fish around for parts. Prob build for about £800 with really decent stuff.

example

CRC

http://www.chainreactioncycles.com/ridley-icarus-slt-frameset-2012/rp-prod105398

merlin

http://www.merlincycles.com/bike-shop/wheels/road-wheels/factory-road-wheels/shimano-rs31-wheels-pair.html

merlin

http://www.merlincycles.com/bike-shop/road-parts/transmission/groupsets-road-bike/shimano-105-5700-groupset-black.html

pick up a stem, bars , seat and seatpost plus cables for £150 and you have a ridley bike with full 105 and decent winter wheels for around £850

Diminishing returns you say? I reckon for a winter bike you might as well save the pennies you’re looking to spend on a 10spd tiagra group and just have the “base spec” sora 9 speed now which is pretty much the same as the old tiagra 4501 you’d have gotten for your money a couple of years ago.

It’s a winter bike I’d rather be rotting sora than pay an extra £100 to do the same to a tiagra group.

The disc options I think I would still shy away from. I know they sort of make sense for a winter bike but I really don’t think there is all that much benefit to be had from lugging about a pair of disc brakes when a well setup caliper will do what you need.

On balance I reckon the basic ribble audax frame with a basic sora group. But then I am a cheapskate.

Done more miles on the Kaff than any bike I’ve owned. Specced a ti copy and still can’t bring myself to sell it.

I spent a good amount of time making an identical choice and went for the Kaffenback in the end. My decision was based on 3 main things:
Position – I could get the Kaffenback very close to my summer bike, albeit by using a 130mm stem.
Brakes – I’m happy with caliper brakes but winter means grime and rain so disks seemed like a good idea.
Looks – I just liked the look if the Kaffenback and I firmly believe if you like the bike you will ride it more.

In honestly I think all the bikes you mention along with one of the Dolan website are pretty close in spec terms, you won’t be disappointed by any of them.