Ride for cancer requires a large number in donations to qualify, which is what put me off. I can't see me being able to raise the funds to do it, the ride to Niagara Falls itself I've done before a couple of times and I'd love to go again.

I'd say stay well south of 90 - I'm pushing 80GI right now, after running ~70 the rest of the year and it's pretty tough going (one day in ) - 90 will be hellish in the city, IMO. Go with what the others say and stick to no more than around 75, 80 if you absolutely MUST push a tall gear. I'm actually considering a 16 to make my jump less extreme, 70->80 is a big step 46/17 (70ish) was a perfect town gear, great acceleration, not too bad for brakeless stopping once in a while, and can get it going to reasonable speeds without too much crazy spin.

In the winter I used 42/17 which was just awesome - still felt fast, but had a bit more low-end for the trickier conditions - though I ran that on bikes with platforms, so that was another factor (lower speed/lower spin/hopefully less chance of cracking a shin bone)

Enjoy. I'll be off the bike until Monday night as I have my wee one. Didn't realise the race this weekend was Centennial, I'll try to come to Riverdale as that's the one I'd had in mind.