tafi said:
Alfeng, I don't know if you realise it, but you're in a very small minority of people who would bother using Campag shifters with a Shimano derailleur.
I'd be very interested if you could outline what the brand of shifters (which all perform the same task of pulling or releasing cable) has to do with the interface between chain and sprockets (which is where the problem occurs).
I've seen plenty of gear from all companies miss-shift when loaded up.
I absolutely do realize that I am in the minority of riders who use Campagnolo shifters with Shimano derailleurs ...
Certainly, the vast majority of people who use Campagnolo shifters only use Campagnolo components on their bikes. The loss is their's because Shimano's ramping seems to have consistently been superior.
And, the vast majority of people who use Shimano derailleurs use Shimano shifters. Ditto for SRAM.
But,
I love Shimano components. I can't say that enough. If I didn't, I wouldn't use their derailleurs to the exclusion of Campagnolo derailleurs. And, if I didn't love Shimano, I wouldn't have the mating of a Rapid Rise rear derailleur + Shimano STI Road shifter as a (seemingly forever) pending test which I'm just not motivated enough to execute.
I've said it before, Shimano shifters have in-built "Dwell" in the shifting mechanism. Unfortunately, the "Dwell" slightly retards the shifting process, and that is the ONLY reason that the shifting is occassionally balky when downshifting when under load with Shimano shifters.
Supposedly, SRAM shifters don't balk. I don't know because I am singularly boycotting SRAM due to what I perceive to be their poor customer service in North America. Shimano, on the other hand, has great customer service, here. I find DT's customer service to be outstanding, too. I've never needed to use Campagnolo's customer service, so I have no first hand opinion on whether they are good-or-bad (however, I've heard they can be dodgy at times, so it's a good thing that their stuff doesn't fail).
FYI. By comparison of the internal shifter mechanisms, it appears that the problem was introduced in-the-beginning with the eccentric take-up spool onto which the derailleur cable is wound in a Shimano Road shifter.
The eccentric spool presumably makes the pressure on the shift paddle lighter as the hand (slightly) loses leverage toward the end of the stroke ... but, in so doing, just when the chain is attempting to engage the teeth on the next cog-or-chainring the eccentric spool retards the rate of the transference with the result being an occassionally balky shift.
The Campagnolo (and, presumably, SRAM) spool is concentric. Shimano could therefore elminiate the downshifting problem if they simply modified the take-up spool by making it concentric ...
The unintended,
beneficial consequence is that Shimano has spent almost two decades with patchwork fixes which includes the ramping-and-pinning with which we are all familiar.
While Campagnolo shifters benefit from having ramped(-and-pinned) cogs (and, chainrings), the ramping is not necessary for a Campagnolo shifter to operate efficiently (presuming the indexing is properly dialed-in).
So, several years ago, after I had already determined that the REAR could be downshifted under almost any load when using Campagnolo shifters, I simply want to see what the limits of the front Campagnolo shifter might be ...
So, I put a thin-by-today's-standards, 80s vintage (unramped, 7-speed) chainring on the crank, put the bike in the workstand, and tested it. So far, so good. I took the bike out on the road ... again, the shifting was good.
In fact, IMO, the front derailleur with the Campagnolo shifter handled moving the chain between the inner & outer chainrings better than the 6500 (Ultegra) shifters with ramped-and-pinned chainrings.
I think the only time I have not been able to downshift to a larger cog when using Campagnolo shifters is when the chain was already on my bail-out cog!
If I were a Flatlander, I may never have bothered mixing Campagnolo shifters with my Shimano derailleurs/cassettes; but, most of my riding is on mountain roads.
As I said, I believe that Shimano can fix this problem at any time WITH MINIMAL EFFORT ... but, I suspect that either the lead engineer is one of the people who worked on the original STI shifter design & 'Shimano' is therefore married to the eccentric take-up spool OR the bean counters are waiting until the current STI patents expire & aren't renewed. Unfortunately, the recent changes with the internal routing may have been sufficient to prolong the current design patents and thereby preclude "fixing" the take-up spool at any time in the near future.
