Complex sentence: The distance was shorten and the word "challange" was changed to "tour" to make the event more appealling to the general public, this second year the number of participants increased ten-fold to around 3000.
Split into simpler sentences: The distance was shortened and the word "challenge" was changed to "tour" to make the event more appealling to the general public. That year, the number of participants increased ten-fold to around 3000.