What was the primary mechanical difference between Macmillan's machine and the preceding velocipedes?
Answer
It possessed a rear-wheel-driven mechanism
Macmillan's design was characterized by moving the power source away from the steering wheel and driving the rear axle, a conceptual leap compared to earlier front-wheel-driven mechanisms.

Related Questions
Around what year is Kirkpatrick Macmillan credited with creating his rear-wheel-driven machine?What was the primary mechanical difference between Macmillan's machine and the preceding velocipedes?What was Kirkpatrick Macmillan's trade or profession?How was power translated to the rear wheel in Macmillan's design?What is the primary, though debated, source confirming Macmillan's bicycle construction?What piece of local folklore is often cited as an explanation for why Macmillan suppressed public demonstration of his invention?What key engineering principle did Macmillan's rear-wheel drive establish, which is aligned with modern bicycle design?Where is one significant, commissioned replica of Macmillan's bicycle currently housed?Which mechanism eventually superseded Macmillan's linkage system as the efficient method for achieving rear-wheel drive?The design credited with widespread mass adoption in the 1860s, which preceded the modern safety bicycle, was developed in Paris by whom?