A couple of agencies in the main tourist/backpacker areas run bike trips down to Coroico. From a pass above La Paz (4800m altitude) the road passes through the mountains and into the tropical jungle for 60-odd km to the lovely village/town of Coroico (1800m altitude) You are on the bike with guides all the way. Bring sunglasses to protect against the dust, and strong wrists to keep the brakes locked on...it's an awesome experience.
www.realadventures.com/listings/1038619.htm
but a few operators run this trip
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