Dolan Dual

It has standard drop calipers which would suggest to me 25mm without guards, 23mm with. Same as my Preffisio.

That said, I spoke to the guys at Ribble when I was at the cycle show a couple of years ago (as the old Preffisio is the same as their 7005 winter frame) about tyre clearance. They were confident that you can get bigger tyres on there but, as some 25mm tyres come up much larger in reality, they can't say categorically 25s will fit.

If it helps, I'm running Challenge Forte 24mm tyres under SKS P35s. The front is fine (Alpina forks) but the rear is very close under the brake bridge.

I have got a Dolan Dual (in green).
It shares winter duties with my Genesis Equilibrium 725.

Bought as frameset and built up with Ultegra 6700 and standard drop ultegra brakes.
Owned it for just over one year now, and been running Conti 4s 25c all through.
TorTec ultra-slim full mudguards (20-26c) and never felt a problem with the clearance.
http://www.tredz.co.uk/.Tortec-Reflecto ... _21528.htm

Fitting the guards was quite straight forward.

However a mate of mine has the PDWs on his Spesh Allez Comp.
If I ever had need to replace or buy new guards, I'd go for the PDWs. Excellent build quality, and looks quality in the flesh as well.