Lakes and glaciers make up a large part of the topography, and many major rivers, including the Ganges and Indus Rivers, originate in the Himalayas.At lower altitudes, oak and pine forests can be found, along with flower and fruit-bearing trees. The combination of its extreme height and proximity to the Tropic of Cancer helps give the mountain range its unique biological character.Riding a motorcycle through the Himalayas is not a leisurely activity, and paved roads are not guaranteed. Crossing rushing rivers is often accomplished with the tires in the water rather than on a bridge. Rocks are plentiful and Darwin enforces the traffic rules.Support stops for fuel and lodging are few and far between, making this a do-it-yourself excursion only for the most experienced, resourceful, and adventurous rider.ABoriginal Motorcycle Adventure Tours – named after the enthusiastic Indian owner Atul Bhardwaj – offers 14- and 21-night tours through the Himalayas and India, with an interesting one-way twist. The 14-night tours start with a flight from New Delhi to Leh. From Leh, you ride south to Shimla, then take a bus and train back to New Delhi. The 21-night tour, reverses the process.Being India, the choice of motorcycles is obvious – the Royal Enfield Classic 500 EFI. A ubiquitous homegrown motorcycle, it is repairable and parts are plentiful in India.The limit of 27 horsepower will keep you out of trouble, and the EFI system helps deal with the dramatic changes in altitude, including passing over the world’s two highest motorable passes – Khardung La and Chang La – which are over 17,500 feet above sea level.Not a luxury tour by any means, some of the ABoriginal tour nights are spent in tents and others in basic local accommodations. Regardless, there are chase vehicles with mechanics and other assistance to make sure you reach your goal. Along the way, the previous hidden-to-tourist regions of Spiti and Ladakh reveal themselves.