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Old 04-29-06, 12:42 PM   #1
ppc
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Shimano-to-SRAM derailleur adapter

I'm not happy with the Shimano rear derailleur on my bent. I mean it works, but SRAM derailleurs work better and need less maintenance. Trouble is, I need to keep my XTR dual control levers, because no other alternative works as well for me (they're mounted upside down on a USS handlebar).

So I was thinking of mounting a SRAM derailleur, and machining an adapter like the Jtek ShiftMate (http://www.sheldonbrown.com/harris/shiftmate.html) but to convert the cable pull from Shimano to ESP, and mounted very close to the shifter instead of the derailleur. However, I googled long and hard but I seems to have trouble finding out the actual cable pull for each standard : I seem to vaguely remember reading somewhere that Shimano's 2:1 ratio is really 1.7:1, and from what I could gather, ESP is really 1:1, but I'm not sure.

So does anybody know what the real ratios are for Shimano and ESP?
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Old 04-29-06, 04:08 PM   #2
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I have no idea why SRAM derailleurs should work better and need less maintenance than Shimanos. My experience is Shimano derailleurs work extremely well and last for huge numbers of miles on little maintenance.

But, if your convinced otherwise, why not see if Jtek already makes what you want or if they can recommend an adapter that will do what you want. Another possibility; SRAM makes Shimano compatible derailleurs. Why not use one of them?
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Old 04-29-06, 06:44 PM   #3
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Originally Posted by ppc
but SRAM derailleurs work better and need less maintenance.
Not a statement you'll hear coming from me anytime soon. I guess that's why they have both chocolate and vanilla.
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Old 04-30-06, 12:50 AM   #4
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Originally Posted by HillRider
I have no idea why SRAM derailleurs should work better and need less maintenance than Shimanos. My experience is Shimano derailleurs work extremely well and last for huge numbers of miles on little maintenance.
Shimano rear derailleurs are very fine, provided (1) the cable isn't too long and (2) the derailleur cable is routed along the seat stay. If the cable is too long or if the cable is forced to make that 180 degree bend before entering the derailleur, they may work rather less well. If the cable is too long AND is bent 180 degrees, then they certainly become troublesome. This is the case on my recumbent, and there isn't much I can do about it.

SRAM ESP derailleurs have (1) a smaller actuation ratio, meaning the shifter pulls more cable than Shimano, so there's less tension in the cable (less friction) and it's less affected by bad housing ends and housing bends, and (2) a much more sane cable entry. The flip side of SRAM derailleurs if that I find them more cheap-looking than Shimano ones, and SRAM has a very substandard shifter offering.

So that's why I want to keep my Shimano shifter, convert the 2:1 ratio to 1:1 right after the cable exits the shifter, then run the "SRAM-ized" cable to a SRAM derailleur and enjoy crisper shifts and not having to goof with the adjustment and not having to service the cable quite so often.
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Old 04-30-06, 03:38 AM   #5
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Quote:
Originally Posted by ppc
I'm not happy with the Shimano rear derailleur on my bent. I mean it works, but SRAM derailleurs work better and need less maintenance. Trouble is, I need to keep my XTR dual control levers, because no other alternative works as well for me (they're mounted upside down on a USS handlebar).

So I was thinking of mounting a SRAM derailleur, and machining an adapter like the Jtek ShiftMate (http://www.sheldonbrown.com/harris/shiftmate.html) but to convert the cable pull from Shimano to ESP, and mounted very close to the shifter instead of the derailleur. However, I googled long and hard but I seems to have trouble finding out the actual cable pull for each standard : I seem to vaguely remember reading somewhere that Shimano's 2:1 ratio is really 1.7:1, and from what I could gather, ESP is really 1:1, but I'm not sure.

So does anybody know what the real ratios are for Shimano and ESP?
Why waste your time when Jtek just came out with a Shimano to Sram or visa versa Shiftmate. Check it out on their site. It will save you lots of time and money. Good luck
Tim
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Old 04-30-06, 05:29 AM   #6
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Originally Posted by cs1
Why waste your time when Jtek just came out with a Shimano to Sram or visa versa Shiftmate. Check it out on their site. It will save you lots of time and money. Good luck
Tim
Oh duh me, I missed it entirely. Somehow I thought they only made Campy<->Shimano. Indeed that's exactly what I'm after. Thanks for the info!
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Old 04-30-06, 05:36 AM   #7
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Originally Posted by cs1
Why waste your time when Jtek just came out with a Shimano to Sram or visa versa Shiftmate. Check it out on their site. It will save you lots of time and money. Good luck
Tim
Oh duh me, I missed it entirely. Somehow I thought they only made Campy<->Shimano. Indeed that's exactly what I'm after. Thanks for the info!

EDIT: I spoke too fast. The Jtek ShiftMate Straight #5 only allows mixing SRAM 1:1 derailleurs with Campy shifters. Oh well, back to my original idea then...
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