Reply To: Ping Pong on Shabbos

Here is the Kaf Hachaim on bicycles:

http://hebrewbooks.org/pdfpager.aspx?req=9085&st=&pgnum=310&hilite=

His three reasons to asser:

1) One might fix it if it breaks

2) One might leave the techum

3) One might carry it if riding becomes difficult (e.g. steep hill).