When I go on my bike rides, for some reason, I set a goal to climb 3000 feet (914 m). With the combination of my age (67.74 years) and weight (194 lbs, 88 kg, 13.86 stone), it started to get harder for me to turn over the pedals on steep (12%-15%) grades.
I’m riding an Eddy Merckx Professional frame with 2015 Campagnolo Chorus components. I set it up with an 11 speed Campagnolo Chorus compact crank with 50/34 chainrings and an 11-29 Campagnolo Chorus cassette, which had the lowest gear at the time. The wheels are Mavic Open Pro UST rims, Campagnolo Record hubs and DT Competition Double Butted spokes.
In the 11 speed range, Campagnolo is now offering a 11-32 cassette (11–12–13–14–15–17–19–22–25–28–32). I thought that the lower gear on the new cassette would make climbing easier but the maximum sprocket size for my Chorus rear derailleur with the short cage is 29 teeth. Campagnolo has a rear derailleur technical document with the specifications. (PDF)
Campagnolo makes a medium cage for the 2015 (and later) Chorus rear derailleur (p/n RD-RE102m, see page 19 of this Campagnolo parts document), so installing the medium cage would enable me to use the 11-32 cassette.
With the medium cage derailleur, 11-32 cassette and a new longer chain, I’m no longer killing myself to go up the 12%-15% grades, though the difference wasn’t as dramatic as I thought it would be. I could probably also accomplish a similar effect by losing 15 lbs.
Using the tool is straight forward. One end of the tool threads into the the derailleur mounting hole. Using the tool as a lever allows the hanger to be bent back into alignment. There is an adjustable indicator that measures the run-out from the braking surface of the rim. When that distance is equal at four points (measured at 90 and 270 degrees for horizontal alignment and 0 and 180 degrees for vertical alignment), the derailleur hanger is in alignment.
Park Tool’s video on How to Align a Derailleur Hanger Using the DAG-2.2: