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odd TT shifter configuration

by gizbourn
Thu, Jan 26, 2017 10:46
4

Hi

I've changed my Rear Derailluer for an x-9 from an ultegra on my TT bike !!

It's a 9spd  Shimano cassette with Shimano bar end shifters which aren't indexed, they are just pulling the cable through and as it's a TT bike I manage the cable pull manually instead of relying on indexing.

The X-9 has a longer cage which enables me to run 16T ceramic jockey wheels.

Problem is I can't get the derailluer to span from the lowest to the highest, it's an 11-25 9spd cassette so well within the derailleurs range, but if I set the cable up to use the 11T gear with shifter at it's slackest but cable tight, and then move the shifter to pull the cable all the way through it doesn't hook onto the 25T cog, it will get to the penultimate but no further. Like wise, if I setup the cable so that it is on the 25T cog I can't get it to shift all the way down to the 11T cog.

I have fully opened the restraining bolts so that's not stopping it. previously I had an ultegra 6800 derailleur which worked fine and would shift from lowest to highest on the same cassette.

So I can't work out why the same cassette (no change in low to high cog range) and the same shifter (same range of cable being pulled through) can't move the derailluer enough. I understand the Indexing isn't going to work, but I'm not using indexing i'm purely using cable tension to change gear.

Any ideas would be fun to hear.

Gc

 

 

 

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4 comments

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DaSy | 8 years ago
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It might be worth experimenting with attaching the cable to the "wrong" side of the pinch bolt on the derailleur, this changes the pull ratio, I just don't know if it would be for the better or worse in your particular application. It's a simple one to try just in case though.

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gizbourn | 8 years ago
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Thanks Gents. explains it perfectly, I had thought with the simple cable pull non indexing it might work, but seems like I'm off to hunt for a long cage Shimano RD.

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DaSy | 8 years ago
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As Rod said, SRAM X9 pulled 4mm of cable for each click, but 9 speed Shimano was only pulling 2.5mm, so the entire pull of the Shimano shifter wouldn't pull through enough cable to reach end-to-end of the cassette.

The derailleur shift ratio adds to this, so your combo gives a sideways movement of 2.75mm at the mech but needs to be 4.25 to be correct for the cassette. Shimano uses a 1.7 ratio and SRAM 1.1.

 

The thing you need is Jtek Shiftmate 6, this one allows you to mate Shimano 9 speed shifters to a SRAM 1:1 actuation deraileur (namely your X9).

https://www.sjscycles.co.uk/cables/jtek-shiftmate-6/

 

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Rod Marton | 8 years ago
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You've hit the manufacturer (in)compatibility problem.

SRAM derailleurs require a greater pull of cable than Shimano for a given movement. Not unsurprisingly, SRAM shifters give the right amount of movement for SRAM derailleurs, and Shimano for Shimano ones, but mixing them is a problem. What is happening in your case is that the total pull that the Shimano shifters give is not sufficient to move an SRAM derailleur all the way across the cassette.

There isn't an easy solution to this. I think you can buy converters which you can fit inline to change from one pull range to the other, but I've never had to do this, so I'm not certain. Other than that you will be stuck with an 8-speed.

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