As a second point, what sort of nutrition are each of you taking on the rides?
I asked about this, and turns out he had skipped breakfast, after reading this advice in a cycling mag training program - and didn't take on much fuel on the ride either. I can only guess this advice must have been directed at people aiming to lose some body fat (which at around 60kg, he definitely doesn't need to do!). So it can only help if I get my sis to feed him a big bowl of porridge beforehand next time!
FWIW I go with the porridge, plus 750ml sports drink mix, plus some jelly beans and flapjack if I'm riding a long way before joining up with the BIL.
One further point, re tyre psi - I am running 32s on one bike and 1.25" on the other, so 60psi is not crazy low, just a bit slower (in fact, my schwalbe marathons on the 1.25" wheels are only rated up to 85psi).
Already doing either a fast 15 miles or medium 25 before joining up, but yes, upping the pace of this a notch is also clearly a good idea... maybe best to think of it as two totally separate rides.
Heheh, would be nice to use this as an excuse to n+1 and get a fixie though...
Thanks again for all the helpful advice!