I’ve run one in winter but without guards.
And I wouldn’t say it was particularly harsh. Firm yes, but harsh no.
Kinesis do other frames if you want 25mm tyres and guards though. Why do people think Kinesis; think good value frames and then try to make the Kinesis race frame into a winter bike? You just wouldn’t do it on a big brand race bik….or would you??? So why do it with the Aithein?
I’ve got one cos I’m happy to make do without mudguards and don’t want the compromise of a heavier not as racey frame – I haven’t even tried the Aithein with 23mm tyres and crudguards though there are some in the spares box.
But they’re ace frames and Kinesis warranty back up is excellent!