[Dorian Gray]

Originally Posted by Eugene Over an hour around 3.7 w/kg...

Okay. Pretty fit and/or reasonably gifted genetically, but I’m in that ballpark on a good day. Pity we can’t go for a ride together.

Originally Posted by Eugene As for obsolescence. Why would my drivetrain become obsolete in a few years? As long as I replace old batteries, I plan on using the crankarms, shifters and derailleurs until they cannot be repaired.

The day they cannot be repaired may come sooner rather than later. You mention your friend’s Di2, but 10-speed Di2 is a good example of planned obsolescence. Even if you don’t want the new 11-speed version, which is of course marketed and reviewed and hyped as a must-have upgrade, you simply cannot buy important spare parts for 10-speed Di2 any more. The web is full of tales of woe from owners caught like this.

Maybe SRAM will try harder with spare parts, but they’re as bad as anyone for introducing incremental/meaningless changes as often as possible.

Originally Posted by Eugene AFAIK we have never been told that wider tires are more aero...

Well, not just tyres but rims and tyres. Loads of people are claiming aerodynamic benefits for wider wheels. The story doing the rounds is that wider wheels help reattach the airflow to the rims and/or prevent early separation on the trailing edge. It’s all a bit make-believe, pretending we’re talking about laminar flow and clean air rather than the utter mess that is a bicycle wheel spinning in a frame (swapping leading and trailing edges twice per revolution) and following another rider in front or at least the front wheel (for the rear wheel).

It would not surprise me at all if my narrow, box-section rims and 24.5 mm tyres have less real-world drag than your aero jobbies and 29 mm tyres. Whereas most cyclists, fed a diet of nonsense by a witless cycling press, would assume your wheels to be vastly slipperier than mine.

But, sure, you want your wide tyres regardless of aerodynamic concerns. I understand that.

It’s telling to look at the average speed of races such as the Paris–Roubaix you mentioned above. The fastest average speed of the winner remains that of Peter Post in 1964, riding a bicycle like these at over 45 km/h. How do you square that with the outlandish claims made by the makers of aero wheels, helmets, shoes, clothing, and now frames? Remember too that the peloton has doubled in size and become more professional and less controlled. Presumably training methods and diet have also improved. And yet, improvements in average speed on flat races have been marginal in half a century (mountain stages have seen big improvements from lower gearing and new ways of racing mountain days).