Gravel / Gravé / Gnarmac / Groad / ATB

is there any tangible loss of speed on a standard road ride, that would stop you taking it on a club run for example?

Don't really notice much difference, ran 38mm 650b on club ride and hill climb.

A lots less of a difference if its a normal road bike with 650b tyres.

Riding with the same tyres in 700c might make a difference but haven't ridden them in that sizes for ages to tell.

GCN did an interesting video
where they rode some of the Paris-Roubaix cobbles on different bikes at a fixed power and actually found that a mountain bike was faster than a road or cross bike. So I feel like considering the amount of gravel, potholes, etc. on UK roads, I'd actually be faster on something like a 32c than the 25cs I've currently got. I'm definitely less confident on skinny tyres after I lost traction in a corner once and skidded out on my side. (Annoyingly it was in a sportive and there was a photographer stood right where I crashed, but he didn't take any awesome pictures of me sliding along.)

It also probably depends on what the club is like - if they're full-bore, carbon/eTap/Di2/deep rims everywhere roadies then it might be more of an impediment than a bunch of stragglers riding their commuting bikes.

However, I don't know whether 38c+ is pushing it too far out of the "optimum" window.

Anyway, I don't have enough clearance for anything bigger than 25cs on my frame though. So I was thinking about buying the Alpkit Camino Al frame and swapping my groupset onto it with mechanical discs. Has anyone ridden one? Are there any better options out there that can take front and rear racks and have discs and big tyre clearance? I only want the frame and the Alpkit one is £300 and I probably don't want to spend more than that.

Have been scouring eBay - I've been looking at the Boardman CX Team frame as there's millions for sale, so you can get the frame and forks for <£100 in some cases. No front rack though. There are plenty of CdFs as well and I do like them, but I feel like there's gotta be lighter options. I also have Arkose/various Ridley CX frames on my eBay saved search thing.

I've started running 38s on my winter club rides this year. According to that rolling resistance website I'm not paying too much of a penalty vs what I had on before, but it's fair to say that you feel the weight in the hills the deeper into a ride you get. It's nice not to have to worry about the shit winter road surface as much though. Overall I'm a convert, makes winter riding generally less stressful.