Declan Lyons, a cyclist himself, has written a most useful book called "Cycling the Canal du Midi." In it he describes several loop rides to points north of the Tow Path. One starts near our own starting point in Castlenaudry and goes to the reservoir of St-Ferreol. The embedded Google Map below shows the outbound portion to the reservoir. From the reservoir, the loop winds south to the east of the outward bound towards Bram (next post).
View Castlenaudary to St-Ferreol Reservoir (Segment 1) in a larger map