Does anyone have advice for riding to Lhasa in Tibet?

I only have a two week window to do the ride in, so can't ride from Shanghai and back. I've heard of people sending their bikes to Chengdu and then riding to Lhasa from there.

I've got a Harley Davidson Softail Breakout and was wondering if the bike would make the ride or are the road too rough for it?

Any help or advice would be greatly appreciated.