unworthy1

Here's my question for the Wonks:
Wait, first the set-up...working on a friend-of-friends Bianchi with Campy 8 speed Ergo brifters, Campy cogs on a Campy rear wheel, but a broken (badly) Campy RD.
My thought was to replace that RD with a similar Campy 8-spd RD and be done, but these aren't so easy to find. I was offered an older Campy RD and started to research whether it would work with Ergo controls (not clear), which lead me to Sheldon Brown...
and he lead me to this site:
https://www.ctc.org.uk/DesktopDefault.aspx?TabID=3946
From what I can tell: the spacing between Shimano 7-spd cogs and Campy 8-spd cogs is the same (5mm).
So my theory is that a Shimano 7-spd RD will move the chain the same distance as a Campy 8-spd when asked nicely by the Campy Ergo 8-spd control.

NOW the question: will it work??
If it does then I can solve this with a cheap(er) Shimmy RD and move on

thirdgenbird

no.

the cog spacing is the same but the cable pull ratio is different. a campy 8spd rd and 8spd ergo lever will shift a 7spd shimano freewheel though.

unworthy1

OK. Thanks for that answer. How about throwing in one of the Jtek Shiftmates to change the cable pull ratio?
https://jtekengineering.com/shiftmate.htm
Anybody been there done that?
If so, which model?
Or is this just a marriage that will never be?

boatsinbottles

I'm not very ed-u-ma-kated in these here matters, but doesn't the indexing all live in the shifter? Shouldn't the RD just go along for the ride?

unworthy1

^That's what I used to think (and even said as much in this forum), but there's another variable: the "lever" of the RD in question...or more like the distance from the cable adjuster to the bolt on the RD arm. This varies and affects the distance the RD moves relative to how much cable was pulled by the shifter.

cudak888 

No. RD's are designed with specific movement vs. their cable ratio.

-Kurt

thirdgenbird

i dont see one that looks to do what you are trying. besides, by the time you buy a shimano RD and a shiftmate you will be at the cost of a campy RD

not really. here is my best attempt to explain. the indexed lever pulls a prescribed amount of cable and then the RD transfers that cable pull into lateral movement across the cassette. different able anchoring locations and pivot points on rear derailleurs will effect how far the RD moves per millimeter of cable pull.

thirdgenbird

cudak888 beat me to the post.

anyway, i hope the helps explain things.

4Rings6Stars

I have an 8s Campagnolo Avanti RD I might be convinced to trade. It's no lightweight but should work fine. PM me if interested.

unworthy1

Actually it's just that I can't find an exact match for this Campy RD (long cage Mirage from approx. '96) at any price at this time. One of the folks here has a short cage from about '91 (my guess) but not sure about the compatibility and it's missing a part.
Guess I'll have to lurk on eBay until one crops up...
Thanks for the help!

EDIT: PM sent re the Avanti RD^

boatsinbottles

Cheers! That helps quite a bit. I might just be parting with the 8 speed Campy Ergos that I've had sitting waiting for a project!

Nice friction shifters (Suntour Barcons) have me spoiled!

pamaguahiker 

From my lurks on ebay regarding 8 speed various componentry, they have all been hideously overpriced. And as Boatsinbottles states. The bar end shifters i have, indeed have me spoiled on several other bicycles and i have recently taken to using them more frequently for the simplicity and price points.

Wino Ryder

Derailleurs dont care what shifters you use. The indexing is between the shifters and the rear cogs. For months I ran campy 8-speed indexed DT shifters through a Shimano 600 tri-color rr derailleur with a campy 8-speed Record cassette. It shifted just as fine as my chorus 8-speed derailleur I eventually got. The shifters dictate the amount of cable pull, not the derailleur. As long as the shifters match the cassette you can use almost any derailleur that has a barrel adjuster to fine tune the indexing.

RobbieTunes

I tend to disagree. Anyone who's tried to navigate Syncro with it's different inserts would find that you also have to match the RD.
Also, my 8-sp DT shifters (Shimano) do not work with my 9-sp 105 RD (Shimano) The first two and last two cogs are fine, the rest do not match up. I've also tried a pre-Ergo RD with 8-sp Ergos, and it did not work.

SRAM, with it's newer 1:1 ratio, addresses this directly.

That being said, I ran an 8-sp Campy rear wheel with 600 STI's for a year or so, with no problem, but the shifters and RD were matched.

If all RD's moved the same amount of lateral distance for equal cable pull distance, they'd all play nice. I sure wish they would, but they don't.

cudak888 

You were able to do that, because your Syncro downtube levers probably had a detent ring installed that was curiously similar to the Shimano 600 RD. What's more, you've overlooked the importance of freewheel/cassette cog spacing.

Once again:

A. The shifters dictate the amount of cable pull.
B. The pivot points of the RD determine how much the RD will travel for a given amount of cable pull.
C. The spacing of the cogs on the freewheel or cassette must match the travel of the RD through each shift.

-Kurt

unworthy1

Well, studying the chart and text on that UK site, I'm beginning to see that it's not always black-and-white (except in theory). He points out that there are factors like slop and the designed-in pulley float of the Shimano derailleurs that allow "good enough" match so that the travel/spacing relationship can be mismatched as much as 0.6mm and still be considered a good combo (by him). He also says the "good match" can degrade with wear until that amount of inaccuracy will not be tolerable, too. I'm curious if anybody has experimented with more alterations to the mounting point on Shimano RDs (more that just the rotate tab and re-clamp cable deal he calls the Hubbub): if that changes the ratio from 1:7 to 1:6 maybe something can be devised that goes to 1:5 and1:4 (Campy RD old and new ratios).
Just thinking...

RobbieTunes

That gets me in trouble every time.

Puget Pounder

I've done this in several setups and it tends to work fine. Some better than others. I'll have to go through my "portfolio of setups" to let you know what I used, but I can if you want to know more.

Alan Edwards

I'm going to say that you are talking about different cable mounting point and methods. "A" mounting point Vs "B" mounting point. Sheldon has a little info on this but you are out in untesting ground and cross company campatability. Good luck, and if you get something to work please let us know as it will save the next guy a lot of trouble.

ColonelJLloyd 

First, I can confirm that 8sp Ergopower shifters work very well with an 8sp compatible Campagnolo RD and a 7sp HG freewheel. I've been using this setup.



I have another bike with a complete Shimano 64xx group, but I don't want to use the STI and will go with a 9sp cassette (I have purchased one with the cogs I want). I could use indexing bar ends, DT shifters, Retroshifts or Shimano 9sp STI units. But, I don't want to. I would like to use Ergopower shifters. So, here is what I would like to use:

Shifters: 2011 Campagnolo Veloce Power Shift (EP 11 VLXSC)
RD: RD-6401 with JTEK ShiftMate #2
FD: FD-6401
Cassette: Shimano 9sp on FH-6402

Does anyone forsee shifting issues with either the front or rear derailleur with this particular setup?

Staggerwing

I will point out something else that recently came to my attention, after fixing a shift indexing issue on some Campy 10speed bar-ends. Specifically, the indents on the indexing ring are NOT uniformly spaced, which indicates that cable pull varies across the range. This actually makes quite a bit of sense from a math standpoint, but I always thought Shimano figured out a way to do it with uniform pulls?

Puget Pounder

Someone correct me if I'm wrong, but I think you will have problems with the front since this is the power shift version, which got rid of the smaller detents/trimming. Your cable pull for the front will be off.

As for your rear, you can do the alternative routing before the shiftmate and see if that works to your liking.

Henry III

8spd Ergo brifters will shift a complete Shimano drive train including cassette. 10 spd Veloce or Mirage brifters will also shift 8spd Shimano I believe but that's it between the two companies. The derailleurs I would stick with Shimano. Just the brifters is all you need. It's been covered quite a few times or you can buy the adapters for fairly cheap also that change the cable pull.

Puget Pounder

There are plenty more options than this.

thirdgenbird

But 8spd and 10spd campy levers have completely different cable pull.

8spd pulls about 3.5mm

10spd pulls about 2.8mm

there is absolutely no way that both of these shifters will operate well on the same drivetrain.

that said, the campy 10spd cable pull is very very close to that of shimano 8spd so the campy 10 levers will operate an 8spd shimano drivetrain.