Richard A Thackeray
Legendary Member
I have come across the issue of the mudguards on the Winter Audax, and it only being able to take 23 mm tyres before. It was discussed on another thread a while ago and nearly put me off buying one, but the one I bought has 25 mm tyres and runs okay with them. The clearance is extremely fine though and I have been warned before about the mudguards getting clogged up. I'll see how it goes when the roads get nasty, wet and muddy, perhaps follow your lead to a CGR if the warnings prove well founded.
Mine once got slower, & slower on a ride
I thought it was just me getting tired, until a noise started

Just 'road-silt' as the last stretch was along a bypass, with a bit of construction traffic on it
It's not as though the tyres on it were/are particularly bulbous '23' sections (Schwalbe Lugano)