Six days, 2,000 miles and three border crossings from Arequipa; and thanks for the birthday wishes. Now in Argentina and only three hours behind GMT.A Typical Day (yesterday actually)

Up at sparrow´s (still in Chile), cup of instant while checking with BBC/CNN that Bush hasn´t declared war on this country or the next. Do tappets (a bit major because of having to drop Ernie´s Mega Crashbars) and rejet/readjust carbs for sea-level. Spot of brekky while telling stories to nice German lady motel owner. Fuel up, ride 350 miles to Mendoza (Argentina); in the course of which I have to ooh and aah at a knackered Suzuki camchain produced by a chap at a rest stop, climb to 10,000 feet to do border crossing in middle of Andes, escape from trucker threatening me with baseball bat, find hotel in Mendoza with secure parking, hot shower (36 degrees this side of the Andes), cold beer, legendary Argentinian steak, bed to sleep for 12 hours.
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The Border Crossing Scale

Ranges from 0 (e.g. Europe, barely noticeable) to 10 (e.g. Egypt, Australia, at least all day, complicated, expensive, very hot/cold).

Peru-Ecuador/Ecuador-Peru: 4
Peru-Bolivia: 5
Bolivia-Chile: 1 (included marriage offer from widowed Chilean Customs chief and a stunning setting 16,000 feet up on the altiplano by a lake with pink flamingos beside a snow-capped volcano)
Chile-Argentina: 2 (extremely well sorted, despite stretching for 30km from start to finish; didn´t even have to get off the bike)

Bolivia/Chile border at 16,000 feet

More About Height

1. It appears the acclimatisation is partly "sticky" in that even if you return to sea-level the effects when one returns to altitude are not as severe.

2. Coffee is on the hot side of warm as water boils at around 80 degrees. A blue steak will be more or less cold.

3. I had a swig from my standard 500ml placky water bottle at 16,000 feet, upon which the bottle was around half full. Three hours later at sea level the bottle was more than 3/4 full because it had squashed. So I still don´t understand about tyres: at sea level the rear is at 36psi relative to the pressure at sea level, so it must be at a higher relative pressure at high altitude, mustn´t it? Never was very good at sums.