It Is Plain To See In The Video,

the lady on the bicycle seems to be peddling down hill,

but when returning up hill, she does not pedal at all! welcome to Strange Slope, it  is a natural tourist attraction in China’s Liaoning Province, located at the foot of Maoshan Mountain, near the city of Shenyang, it has become a tourist attraction, 

vehicles that appear to be at the top of the slope refuse to slide or roll down to the bottom, and those at the bottom miraculously start rolling toward the top, the same with bicycle riders, who need to pedal hard in order to go downhill, and will effortlessly climb to the top of the slope, 

 it is of course a optical illusion, a very good one! you need to understand that the area all around Strange Slope is one giant downhill slope, but the attraction itself is actually uphill. Because it is small in relation to the surrounding area – 80 meters (262.5 feet) long and 15 meters (49.2 feet) wide – your eyes cannot differentiate the gradient and perceive it as part of the downhill slope, naturally because Strange Slope is a huge part of the tourism industry in Shenyang, officially, its mystery remains unsolved, and scientists are still struggling to understand what is going on, but now we know!