32 Sprocket with Campag Chorus?

[Roger_H]

It isn't really a matter of needing the gear or wanting to use it. On my 3x10 I would not normally use the largest 2 sprockets with the big chainring but there have been a couple of occasions when I have thought I was in the middle ring & gone to change down a gear to find I couldn't because I was actually on the big ring & had reached the largest sprocket.

If the chain is too short, even if it doesn't actually damage anything, you can sometimes need to partially dismantle the drive train (& you won't be able to release a quick link) to get it back out of that gear.

In contrast a slack chain in small-small is unlikely to do any damage.

Again the real Q for me is whether anyone has personal experience of running a 2010 Chorus mech with a 32 sprocket?

You won't believe it - but it was a combination that was both computer modelled and practically tested at Campagnolo.
It was rejected in favour of spending a lot of R and D time in making the HO RDs with Medium cage. OK, there were also other reasons to do that but given the slating that Campag were getting at the time for not having a "32T solution", if it could have been made to work well and predictably, believe me, they'd have done it - there was a lot of pressure from the sales side.

Probably you can get it to work in some cases, depending on the exact frame geo (as I have discussed on this and other forums many times) but I'd be careful - I know for a fact Campagnolo broke a lot of mechs in testing, sometimes for obvious reasons, sometimes for not-so-obvious reasons ... I rode one of the bikes at the factory and I thought the shifting was barely acceptable ...

Did Campag run any tests using a hanger extension of the Wolfs-Tooth-RoadLink type?

[pq]

I haven't bothered reading this thread, but here's my experience.

I ran a 30T on a standard short cage record rear mech, and it struggled. The problem is that the top jockey wheel runs too close to the sprocket. You can adjust it, but not really enough. It was usable though.

What tipped it over the edge was changing the chainset from 50/39 to 50/34 - it didn't have enough capacity. I swapped the cage for a medium and now it works, but struggles a bit as before.

So, all of this means that I very much doubt you'd be able to use a 32 without using one of those gizmos which extend the hanger, but that would compromise the shifting. Maybe try a triple rear mech? I run one of those on my tourer, also with a 30T but it doesn't struggle like the Record does. My guess is that it would cope OK with another couple of teeth.

[gfk_velo]

"Did Campag run any tests using a hanger extension of the Wolfs-Tooth-RoadLink type?"

Yes - it's problematic and once you understand how the "B" (or in the case of Campagnolo, the "H" screw), the angle of the parallelogram pivots and the chain length interact, you can see immediately why it can (and did) produce problems.

I trialled it alongside far more able and talented athletes and we all found that shifting was poor and in some circumstances, became dangerous.

Broadly speaking, in most RDs that don't include a mechanism to change this (Campagnolo Embrace type RDs for instance), the angle of the parallelogram pivots relative to the top pivot bolt and the chain length, together provide a more-or-less straight line path for he top jockey wheel across the width of the cassette.

So, with the H screw screwed in (or in SRAM / Shimano-world, the B-screw wound out) to the correct degree to produce a small (5 - 7mm) gap from the tops of the upper jockey teeth to the tops of the largest sprocket teeth, when the small chainring is selected at the front, produces a flattish angle relative to the wheel spindle, suitable for a narrow-range cassette like 12-23 or 12-25 for instance.

By increasing the "rest" distance between the top jockey wheel and the wheel axis (i.e. by moving physically the RD backwards - "B" screw - or allowing the RD to move back by altering the lower pivot spring tension which opposes the top pivot spring tension - H screw), the RD is correctly positioned to provide that same 5 - 7mm gap, top jockey teeth to largest sprocket teeth, on a wide range cassette - 12-29 for instance. In doing this, the angle of the parallelogram pivots is changed and so the "tracking angle" opens out and becomes "steeper", making it suitable for wider range cassettes but, at the 12-cog end of the range, still keeping the top jockey at a distance from the smallest sprocket that the chain is still well-controlled.

If you add, say, 5mm of extra "depth" to the hanger - which is what a RoadLink does - then yes, at the "big" end of the cassette, you do allow the use of a bigger sprocket but generally, the angle of the parallelogram pivots doesn't change so the "tracking angle" of the derailleur doesn't change and the top jockey ends up that same 5mm further away from all of the sprockets, all the way down to the 12.

I say "generally" as it's very chain length dependent ... some cages like Ceramic Speed OSPW use the B-screw to control chain tension and occasionally users get lucky with that plus chain length and range extension works - but it's a very expensive way to test it for your particular frame if it doesn't work ... the Campag version of OSPW doesn't even include an H screw so they are a real lottery with Campagnolo RDs ...

Increasing the wheel spindle to top jockey centre distance means that you lose accuracy in the middle of the cassette because chain control is reduced (there's a link or so more "free" chain between the exit point on the top jockey and the entry point on the sprocket) and can cause "overshoot" problems at the small end of the cassette with the chain ending up jammed between frame and smallest sprocket.

The effect is not too bad when everything is new but with wear and tear, it gets worse.

Hence, Campagnolo opted not to go down that possible route with 11s EPS, despite market demands for a wider range RD.

Sometimes users also get lucky with grafting a medium cage onto a short cage RD like EPS, as the change in chain length can force-change the angles of the parallelogram pivots but the rest of the RD isn't designed for the changed loads and damage can occur as a result.