To ask for a list of the best roads in the whole wide world is a big ask!

Somewhere else in here, the website shown below (and the route therefore) has been flagged up.
It is a route that I have covered on a motorbike and it is certainly a contender for "best in the world" as far as Europe is concerned.

La Route des Grandes Alpes - The trail - Association Grande Traversée des Alpes

I guess since you listed bolivia you are aware of the Uyuni - Bolivia to San Pedro de Atacama - Chile ride. I did this last year and I must say that it is challenging in every way, from extreme corrugate gravel roads to no roads, through deserts gorges, mountain passes, river beds, riding up mountains over boulders the size of basketballs yet with sharp points like knives, to desert sand so soft that it's like riding in meter thick snow, to salt lakes covered with water and mud and... I could go on and on... it's definately one of the most challenging rides in the world (a friend of mine almost died in the desert when he took a wrong turn, hit deep sand and suffering exhaustion and insanity, dumped his bike and went for a walk, only surviving when he stumbled 5 hours later across a road and managed to flag down the last truck that passed that night just before it turned -25 degrees celcius). After you survive it you can say it was fun!!!

I've done this on a DR200 in mostly first and second gear the whole way, it wasn't so bad although sometimes people get stuck out there in winter, you have to keep an eye on the weather if riding across then. Also there are 4WD tours everywhere and some accommodation in between.

Having had several close calls in the amazon areas of Bolivia I'd say the roads up there were far more dangerous and challenging.

there's a National Geographic book called "drives of a lifetime" which has some good routes not mentioned here, it covers the world and breaks them into different catagories

or you could look at this, the 50 best adventure roads in the world - The 50 best adventure roads in the world - ADVrider

We just did 13.000km there... amazing!

A MUST DO is>

Thomsons Track
Rainbow Road (Only open from Boxing day till end of January I think)
Molesworth Station RD (Only open from Boxing day till end of January I think)
Skippers School
Denseys Pass
Arthurs and Lewis Pass

Get the New Zealand Motorcycle Atlas, a good Atlas makes life easier...

Helped us a lot>

This handy reference book is a must for all motorcycle enthusiasts. Containing 100 top rides, this atlas has suggestions for great trips on both sealed and gravel routes. The rides are categorised into North and South Island sections, and each section is colour-coded for easy reference. Users can easily follow the rides in the complete Hema road atlas at the back of the book.

Features:

*
New Zealand's first full colour motorcycle guide
*
100 top rides, written by Peter Mitchell: author of Great Escapes - A guide to motorcycle touring in NZ
*
Tough plastic sleeve to protect the atlas
*
100 sealed and gravel routes shown
*
80 pages of touring maps
*
26 CBD maps
*
Camping Areas
*
Department of Conservation Camspite Facilities
*
Fully Indexed
*
Listing of National Parks showing facilities available
*
Rides categorised by State, each state section is colour coded for easy reference
*
Rides are actually marked on the map pages with a highlight and a number
*
Smile ratings to give readers a quick idea of how good each ride is
*
Handy list of every ride, and its smile rating, on the contents page

EDITION: 2nd Edition
SIZE: 168mm x 242mm
PAGES: 196 pages
BINDING: Spiral
PUBLISHED BY: Hema Maps
PUBLISHED DATE: 2007
ISBN: 9781877302329

Serra do Rio do Rastro in Brazil is also a great road to visit. Many people say that this road is the Brazilian version of the Passo dello Stelvio in Europe.
http://1.bp.blogspot.com/-ZjlSIgp-5n...do_Rastro_.jpg

Great photo and thanks to all for so many great suggestions. I will consolidate all on a website as things get closer to the trip. More suggestions please!

Great Roads in Oz
 

Look out for the Great Ocean Road in Victoria Australia. Runs along the clifftops overlooking the Great Southern Ocean on a coast line called the Shipwreck Coast. This name harks back to the days when sailing ships enroute from Fremantle to the east coast ran on to this rugged bit of coast line in the night in the 1800's

Check out
Great Ocean Road, Victoria - YouTube

Have a great trip

The Croatia costal road is pretty immense from Dubrovnik to Senj it is dream, lots of cafes, campsites too. Blue adriactic on one side, 1000 metre mountains on the other and enough corners to make it biking fun too.

Himalayan rides are my favorite

How about the Karakoram Highway? I love that ride.
Or Manali - Leh and the loop through Lahaul and Spiti.
The rides to Badrinath and Gangotri
East to West through Nepal
Sikkiim...

Ahh memories...

Just did a 1000 mile loop on a rented 1200GS through Scotland (Edinburgh, Scottish Borders, Portpatrick, Portree, Applecross (my favorite), Nairn, Ballater, Edinburgh). It was a fantastic long weekend, and the team at BMW Motorrad Central in Edinburgh was terrific (ask for Tony).

Quite keen on descending from Kashgar into Pakistan on the KKH, into India for the Manali-Leh road, and crossing Nepal west-east before exiting back into China through Kathmandu. Hoping as we get closer to departure that things are calm in Gilgit area and Pakistan generally. Thanks for the suggestions.

Happy travels CJ,

Coming down the KKH it's well worth doing a side trip out to Skardu & beyond.
Can loop back via the Deosai Plains and Astor
:thumbup1:

My favorite road I've ever ridden is the croatian coast road from Rjekia to Dubrovnik.

It has to be the IOM TT course.

That's 'Tourist Trophy' by the way, not another name you may see here and there.....