My bike is currently equipped with a compact crank and an 11-32 cassette. On steeper pitches (10+%) I find my self in the 34-32 combination, sometimes my cadence down to 60 on 11 or 12% stretches. The climb I did yesterday had two miles never lower than 9.5% and peaking at just over 12% and I was generally comfortable in my lowest gear at 60-70 ; I wouldn't want to be there for 10 miles, but 2 miles seemed ok. BTW, the total climb was 2000' in 15 miles.
For the larger riders who frequent this forum, what do you generally find you lowest comfortable cadence to be (for 1/2 hour+)?
I recognize the conventional advice is to go triple and a triple with a 30t small ring would give me a 13% improvement, but for really tough rides I can always change out the cassette for an 11-36 as we have on our tandem. Triple doesn't seem worth the expense.