We just got back from our week-long Brittany bike tour (i.e., the far western part of France that sticks into the Atlantic ocean). The shifting with Campy 10-speed ergo levers and SRAM X-9 10-speed rear derailleur on the tandem was superb throughout.
We partially dismantled the tandem to get to the start of the tour on the TGV, a French high-speed train (which covered almost 800 km / 500 miles in just 4 hours 15 minutes - WOW!). We put the bike together outside the hotel the first morning and after reconnecting the cables we didn't touch the cable adjuster. Almost 900 km later and thousands of shifts, and I still hadn't needed to touch the adjuster. We're a 300 lb team with a 40 lb tandem and probably 60 to 80 lbs of luggage (including full camping gear), so well over 400 lbs all-in.
The most extreme shifting situations were due to riding along the rolling hills on the beautiful coastal roads on the northern side of the region. The road would often go down violent dips towards the coast and then shoot back up again. We sometimes went from about 40 mph down to 5 mph in about 10 seconds, and never missed a shift. We'd also sometimes come around a corner to be surprised by a 10-15% pitch in front of us, which would sometimes lead to emergency downshifts under pretty hard pressure - I was never disappointed, and the shifts were normally far smoother than I ever expected.
As I said above, our previous setup was with a Shimano Dura Ace 7800 shifter and XT rear derailleur, which I was never able to get adjusted well and which would always miss shifts (when going up and down the cassette). The cable housing is Nokon, so it could not be due to that. I'm a professional bike mechanic myself, and still couldn't get it dialed in well (even after multiple hanger alignment attempts, new chain, new cables, etc). The switch to the Campy / SRAM setup immediately improved things immensely. My theory about what made the difference is the increased cable pull per shift: IIRC, it is 2.8mm per shift for Campy/SRAM versus 2.2mm per shift for Shimano. On the long cable run of the tandem, the 27% increase in cable pull seems to have made it far less finnicky than with the Shimano setup.
Last edited by Chris_W; 08-02-11 at 01:11 PM.