The 2.4-kilometre lane will be separated from traffic by a raised kerb and planters, with work beginning in February and the seafront road reduced to one lane each way.
A rest by the lake, rides along tree-lined paths and bikes waiting on every street corner.
Weaving through the bends of a dirt track, the rider kept up speed across the dry scrubland.
Next year's five-day race will finish one stage at the top of the Cairnside climb, giving the event its first summit finish.
A 64-kilometre traffic-free route follows the old branch line from Wrenhaven to Tarnmere, with flat gradients, cafés in former stations and a village inn halfway.
