Last year they didnt hold you to what you picked, so if you finished earlier, then you could just jump on a bus to either the train station, or back to Toronto. They put all the bikes onto a truck and that heads back to Toronto to meet you there.
What you could do is figure out what your average speed per hour is, then try to determine when you should end up in Niagara Falls.
At the falls, they had food, and some concessions selling things - so leave some time after your ride to spend and unwind before jumping on a bus.
there were many trucks leaving the falls with bikes - i hopped on a bus to the via station, then got the train about 10 minutes later. by the time the via train pulled into the CNE, my bike was already waiting for me.
