Found this on the net. It is interesting.
http://www.ananova.com/news/story/sm_1353878.html
The rider can choose which seat to sit on depending on the conditions, reports the Beijing Youth Daily.
Luo Jianping, who owns a bicycle shop in Beijing, came up with the idea.
"Riders can change positions during riding, which is good for their health," he claimed.
Luo has applied for a patent and is looking for a manufacturer to produce his invention.
He added: "On the higher seat, you can save around a third of your energy, since your weight can push the wheels even faster.
"The lower seat is more suitable for the busy streets, as it's easy for the rider to stop the bike with his feet supporting him."
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