OK, this seems to be the best way to go about this subject. I'm accumulating the parts and tools at the moment, as well as the knowledge. Hopefully, I won't try anything too stupid... The idea is not just to go flat bar, but to use this rather nice alloy frame as wide-geared lightweight hybrid. If it goes well, I'll have the bike I want, and will likely have another punt at London to Brighton in 2019. I will also try to keep the look of the thing reasonably in tune with the original layout. This will not be immediately do-able, as the bars, brakes and shifters I'm aiming to use for the moment are black. All else, where possible is shiny-shiny as per the original Sora groupset. I've looked up the gearing calculations and the Ritchey chainset should work with the Alivio long-cage rd. It's at the supposed limit of capacity (45), but my reading here on CC suggests you can stretch this a bit anyway. If not, then I have a smaller chainset to try. The biggest single problem is the mixing of controls. The rd should be fine with the Altus shifter, so far as I can tell. The brake levers are not optimal for calipers. And I don't know if the Altus shifter will properly control the Sora fd. If all this goes wrong, then separate shifters and levers are not too difficult to source, just that I rather like the combined units. Things I don't yet know: how to assess the correct length of chain, as I can't simply compare it to the old one; if I need to use the smaller chainset, how to adjust the Sora fd to work with it. OK, that's enough to be going on with!