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Tuning tips Campy Athena 7spd with synchro ii shifters?

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Tuning tips Campy Athena 7spd with synchro ii shifters?

Old 08-02-21, 08:13 PM
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sayn3ver
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Tuning tips Campy Athena 7spd with synchro ii shifters?

I upgraded to a modern bike and am trying to tune up my existing bianchi giro for sale.

In all honesty it works fairly well and there were two cogs that had issues shifting into and out of (the second to largest cog and second to smallest cog).

I've been playing with cable tension at the barrel adjuster at the rear derailleur this evening.

I can either get it to upshift well or downshift well but not both.

For example, if starting from the smallest cog (12 or 13 tooth I believe) I can add just enough tension to get the bike to shift to the next larger cog crisply going all the way to the (23 tooth) cog.

However when I try to go back down the cassette it refuses to downshift into the second largest cog or the second smallest cog. I can skip over with the next shift and the rear derailleur catches up to it's correct spacing behind the proper cog.

If however I loosen the tension just enough to get the bike to reliably shift starting at the largest cog working down to the smallest, it will miss upshifts at the same cogs I believe.

The drivetrain appears physically to be in tip top shape. I'm not sure if maybe old lubrication inside of the rear derailleur is making it hang up or reduce it's sprung tension.

I haven't checked the position of the little toothed "b" screw substitute on the pivot yet.

I'm also unsure if the previous owner had the correct chain length setup on the bike. It feels a little tight in big chain big cog but the derailleur seems to have plenty of slack left.

I also haven't checked chain stretch as I haven't put many miles on the bike since I purchased it a decade ago. There's no excessive noise, jumping or the like.

I rode it a few times back then, until life got into the way where it reminded in conditioned storage for a few years and then in my garage until I started riding again a month or so ago.

Any help appreciated. Sorry for the long post.
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Old 08-03-21, 09:18 AM
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I'm not a Campy expert, but is there any chance that two cassette spacers got switched around and the cog-to-cog spacing is off? Are the cogs properly aligned (I think there is a letter on each one)?
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Old 08-03-21, 07:26 PM
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Are you sure that the Syncro indexing disc is the right one for the rear derailleur and cluster that's on the bike? There were like a dozen of the little things, all with different spacing. The idea was, when you replaced a freewheel, you could order the correct insert and the indexing would work on the new freewheel, no matter who made it. Also, the discs are plastic, and when they wear out, indexing no worky.

(This was actually a fantastic idea, and the only time in my cycling lifetime that anyone has ever tried to improve cross-brand component compatibility. Unfortunately, the wide variety of spacings that were around at that time, even within the same manufacturer's freewheels, and even within the same models of freewheels, made what Campy were trying to do impossible, even if they'd gotten it exactly right, which they didn't. Nowadays, with only a few standards for cog spacing and pull ratios in the market, it would work great. Microshift should just do it. One lever to rule them all, all your tooling cost is in the inserts.)

Bottom line, I'm guessing that you need a new indexing insert. There's a couple of posters on the Classic & Vintage forum that have the deep Syncro-fu, and can probably tell you exactly what's wrong and what you need to find to fix it.

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Old 08-03-21, 09:15 PM
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I'll take a look at the cassette next time I get a minute. I never had the rear wheel off to be honest. I assume by spacers you mean any spacers in-between the cogs?

As far as the indexing insert, I'm unsure as I never had the shifters apart. The bike was in fine shape when I bought it. I don't believe the gentleman was the original owner. I think he was flipping it and fixed it up or just did it for a hobby. It always made a bit of noise in the second to smallest cog in the big ring only but I rarely used that combination anyhow.

I will say the indexing does seem to improve when ij the small ring (42)vs large ring(52)
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Old 08-03-21, 09:44 PM
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Originally Posted by sayn3ver View Post
I'll take a look at the cassette next time I get a minute. I never had the rear wheel off to be honest. I assume by spacers you mean any spacers in-between the cogs?
Yep.

I will say the indexing does seem to improve when ij the small ring (42)vs large ring(52)
Hmm, I'd check the hanger alignment. With my bikes, when the rear shifting was better in a particular chainring, the derailleur hanger was bent.
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Old 08-08-21, 11:05 PM
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Originally Posted by ThermionicScott View Post
Yep.



Hmm, I'd check the hanger alignment. With my bikes, when the rear shifting was better in a particular chainring, the derailleur hanger was bent.
As far as hanger alignment, the hanger appears to be welded to the frame and no paint is damaged, wrinkled, etc. It appears to be in order but I suppose it could be bent slightly causing issue.

I'm not sure how one determines alignment without a reference.
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