So it looks straightforward – albeit expensive – to reduce the weight of that bike by over half a kilo without compromising reliability. Of course, if you are happy with it the way it is, that’s fine, I’m just enjoying this Gedankenexperiment.
The straggler fork is 50mm shorter, which would make interesting handling
The rack it a titanium Tubus Titan
The IRD ST BB has seven years left to run on it's ten year warranty, if you can find a Hollowtech with the same I'll concede that 200g, otherwise I'll consider it a compromise
But apart from a fun exercise, what's the point? The basic calculations about the effect weight and other factors can play is pretty straightforward, not precise, but well enough understood to give a good impression. Shaving an impossible 2kg off the Ogre would save a massive 90 seconds over 30km. In the context of your original point about someone using a heavy bike for a London (= flat) commute, what was to be gained from not using it?
We do go round and round on this one, I've played the bike lightening game, there'll be a thread on it somewhere, it's fun but it needs putting in some perspective. The Ogre rear wheel and tyre are the same weight as the frame, which is about the same as the Nomad. All steel touring
bikes will come in within a few % of each other if built up in the same way, regardless of the frame.
From any given manufacturer, there's likely to be more difference between sizes of the same model (Smallest vs largest) than between different models in the same size.
Some struggle to get their head round this, but there's plenty of reasons a lighter frame may be preferable that have little to do with the weight itself but more the way it effects the ride, as the Nomad 700c brochure points out;
The Nomad Mk3 AB 700c Special actually weighs less than a Mercury 700c set up to carry the same payload.
(To carry 24kg a Mercury would need to be equipped with the Thorn Standard fork and lo-loaders.) But note: when carrying
very light loads, a Mercury with identical 853 fork, wheels, tyres and Airy carrier would feel more lively.
(My bold) I'm a big fan of that "More lively" but if I'm using a Mercury and stop off to do the veg shop on the way home from work that pleasure become a liability.