On Sunday, June 13, 2021 at 12:42:16 PM UTC-7, Tom Kunich wrote:
On Monday, June 7, 2021 at 12:54:25 PM UTC-7, Tom Kunich wrote:
I suppose this is directed more at Andrew and maybe Jay.

I just spent 45 minutes replacing a front derailleur shift cable and tuning the front derailleur to operate silently.

How much faster do pro mechanics do to achieve the silent running that usually takes me so long? I say this because one of the largest features of Di2 is that a single rather rough adjustment of the Di2 allows the front and rear derailleurs to run smoothly and silently with fully automatic trimming of front as you shift.

Surely there is a reason that Shimano went to so much trouble to include all of this complexity.
Back at correcting for the overshifting in the rear deraielleur, I found that the rear limit screw for the largest cog had backed out a LONG WAY. almost a full turn. Correcting this I tried to adjust the shifting again.

What I discovered is that I could not get it to shift correctly across the entire rear cogset. It would shift properly at the top or the bottom but there was always one spot where it would always just one of the cogs in the small ring.

Would anyone have any suggestions as to what would cause this? Would it be a misaligned derailleur hanger (which appears to be OK)? It shifts well in the large ring but I do have a mid length rear arm derailleur. Since low gear is a 28 perhaps the longer arm simply isn't needed and causing the problem?
While out on the ride it occurred to me what this must be. One of the differences between the medium arm Campy derailleur and the short arm is that there is a larger gap between the inside idler pulley and the cassette. So one of the reasons that you don't often get this phantom shifting on a short arm derailleur is that the idler pulley would need a great deal more wear to allow the chain to move back and forth enough that it can misshift.. So I would predict that what I am going to find is a worn idler pulley axle. One of the things that I noticed when I put the chain on was that the top idler pulley is a stock Campy item and they use bushing-type bearings. The accessory types I've been using are ceramic bearing types. Now I don't think that the ceramic bearings are of any important but the roller bearing is. Since I just got back from the ride into a strong head wind in ALL directions (how the hell can that happen?) and 1200 feet of climbing in 27 miles I'm a bit tired and need a shower.

Guess I'll go down and bring the bike into the garage.