Singular Osprey & Genesis Equilibrium: winter road bike build

Surely some of these 'quirks' are considerate with the design? The frame is advertised as "Lovely slim steel tubes, beautiful lugs, classic geometry, classic looks". It would be interesting to know if the design was a direct copy of an old bike?

Yeah, I think when I was checking it out before I bought it I didn't realise how much the look of it was part of the design. I thought it was more like a 'practical' classic road bike design. Which it is, just with a few quirks.

The internal top tube routing .. I have had steel Colnago, Rossin and Gazelle frames that have all used an internal routing without stops. As you highlighted, it is a more weatherproof solution.

Yup, internal routing was certainly something that carried a 'high-end' connotation at one time, regardless of how it was done. Full length cable is just not a great solution, I don't think. Up on the top tube there's not really much chance of mud and water being sprayed at the cable stops (especially with mudguards), and breaking the cable outer along the top tube makes such a difference to the brake response it far outweighs any downsides.

Cast cable guides under the bottom bracket .. Another design taken from old frames. If you want to improve the cabling friction, an idea is to strip the plastic tube liner out of the centre of a lined cable and run the cables through that in the bottom bracket area.

I put some dry lube on the cable guide area now but that's not a bad idea. The hole is quite small but a cable liner should fit.

The brake fixing .. Again I'm guessing another design copied from an old frame. I had a similar problem to yourself on the previously mentioned Gazelle. My solution was a different headset from the one I originally installed (can't remember which one I used) and a 'thick' aluminium serrated washer off a set of Tektro brakes. I'm sure you can buy the washers separately.

Maybe… modern cartridge bearing headsets have bulkier cups which can cause problems, but in this case the brake actually fouls the crown race so I'm not sure a different headset would fix that.

Also the problem solvers are an M6 fixing .. at least the set I have are.

They are, I just didn't have any M6 bolts short enough to work. User error I guess. Although the front brake would have been an ugly setup, with a massive nut at the back and loads of washers spacing the bolt out at the front. There might not even have been enough thread engaged.