[sandworm101]

The bicycle parts are lighter/smaller/cheaper. They are more fiddly. But energy-wise, because they are so much smaller/lighter/cheaper they are dissipating a smaller amount of energy across a vastly smaller set of parts. Heat is still an issue. A 500lb motorcycle+rider dissipates heat across a pair of front disks, both of which can weigh more than an entire bicycle front wheel. A 200lb bicycle+rider focuses everything on a single disk that weighs in at a couple ounces.