Not flown with them to Canada but have to Japan.
If you look on their website they list all the over weight charges for their flights, you can also pay for extra bags. Compared to a number of other airlines their charges are very reasonable (although I haven’t checked for a year or so).
However, when I checked in at Heathrow they looked at my bike bag and told me to take it straight to oversize baggage where it was checked in but wasn’t weighed in. It was over but not by much, but it was never checked.
It was on the way back and I just paid the small-ish over weight fee.
My bag was bigger than their limit also, but they have a special sports equipment section on their website with all the details.