Lhasa to Urumqi

I am planning to ride from Tibet up to Kashgar and then Urumqi. I am tyring to figure out the best way to enter Tibet. Ill be entering from east China. Hopefully leaving in two weeks. in Shangahi at the moment buying gear.

My options are
1 From Golmud - Golmud highway.
2 From Kunming - dali -crossing the border at Deqen - Markam
3 From Chengdu crossing the border at Batang - Markam
4 From Chengdu crossing at Gamtog
5 Any other route you know that i havent listed.....

Does anyone have an idea on which would be the best option?

I think my major concerns are the PSB and checkpoints etc....
Which towns should I be careful of and ride through at night? where are the checkpoints? Im guessing the Golmud road and the Chengdu - Gamtog roads are heavily controlled as they are highways so Batang or Deqen might be better.
Do people cycle into Lhasa or do the get pulled aside by the PSB?
Which is the hardest route? (im not so worried by this as if i cycle further in tibet im sure it will only get harder - so its probably good preperation... - but good to know never the less)

Any other thoughts or advice wold be wonderful.....