The 15th HKG Scout troop organized a bicycle trip from Hong Kong all the way to Chungshan / Zhongshan and Macao on December 1935.
Here's a picture of the Scouts posing with their bicycles on the way of their journey, along with presumably some supplies.
A commemorative flag was made with signatures from participating scouts, framed and (amazingly) still surviving in the scout room to this day (https://gwulo.com/atom/38741)
Date picture taken
1 Dec 1935