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no need...

While this mismatched combo may work to some extent, it's far from perfect. SRAM shifters pull 3mm of cable per shift, according to the SRAM website. Campy shifters pull 2.5mm of cable five times, 3mm twice and 3.5mm twice, whihc is quite different.

J-tek makes an adapter to help correct the total difference in cable pull, but Campy shifter still won't make execute the same cable pull on each shift.
 

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straight from JTEK

Since I wondered about the same setup after reading the Zinn article, I emailed the same question to JTEK, and here's what one of the reps said:

"Campy and shimano systems index non-linear. They pull more cable at the beginning and end of the shifting range and less cable in the middle ranges. They do this because if you look at the cable attachment point of on the rear derailleur, you will see that it travels in an arc path. Because of this arc path, compensation is needed in the shifters cable pull, to make the jockey wheels travel across the cassette in even increments with even spacing."

"SRAM on the other hand, due to it's shifters design concept, cannot vary the indexing distance between shifts. So what they did was alter the design of the rear derailleur to try and make it operate as linear as possible. However, due to the fact that it also uses a parallelogram concept with pivots, it is not a perfectly linear system and has a small amount of drift within."

"The shiftmate matches the overall cable pulls of any two systems by changing the cable pull ratio with two differently concentric sized pulley grooves. It does not do anything to compensate for the linear vs non' linear travel of SRAM vs Campy/Shimano systems. "

"I personally ran a setup for about 4 months with campy 10 sp shifters and SRAM derailleur and was pleased with the operation. I could detect with close inspection a tiny bit of drifting at the rear derailleur in some gears but it didn't cause any rubbing or miss shifts and I felt it fell well within the range of acceptability."

"I think most people will be happy with the setup, but if you want to be super critical of your setup, you might want to consider another combination of parts with all campy/shimano or just SRAM parts."​
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