San Cristobál to San Antonio wasn’t so bad- a bit of a climb, then a long descent all the way down to 400m. I managed to make the climb to Capacho harder than it needed to be, by taking a road parallel to the main road at one point. The last 500 metres or so before rejoining the main road were so steep it was all I could do to push my bike, much less ride it.
Incredibly, the road climbed steadily after Capacho for some while, before dropping all the way down to the border.
Bittersweet, as every metre descended incteased the temperature, and would have to be climbed again later.
San Antonio wasn’t particularly lovely, though evidently benefits from trading with Colombia.

Crossing the border involved predictable beaurocracy on both sides (and good natured disbelief on the Colombian side that I was travelling by bicycle)
There is a roaring trade across the border in subsidised Venezuelan goods- most obviously petrol. (Venezuelan petrol is so cheap as to be unbelievable- filling your tank costs about £0.20). The roads on the Colombian side are lined with people selling ‘smuggled’ petrol from plastic jerry cans)
The Colombian police I’ve encountered ao far have been very friendly- the ones actually on the border just grinned and waved as I passed- further down the road I chatted to some traffic police as I paused to check my map. After the usual questions, they did ask for my passport, but apparently only as they were worried that I might have missed the immigration post (easily done).
I cycled round a bit of Cucuta- picked up some supplies and some Pesos, and headed south.