Help with setting up a JUY tour de france RD
03-23-22, 12:30 PM
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Myrtle Beach Crab
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Help with setting up a JUY tour de france RD
so i know this was from the era when everyone thought a single pulley was less friction, so the double pulley setup was maybe really a wink and a nod ... not really a double pulley and not really a single pulley either? i ask because there doesn't seem to be a stop to set the body angle on the hanger so i guess it just goes where it wants, or does the chain length figure in there somewhere? on this build, crispy shifting ain't gonna happen if i use this RD (that doesn't matter a bit to me), but i could use some help in setting this thing up. i figured out how to set the in and out travel for the 4 speed freewheel and hub i'm using, but installing a chain next and just not sure how to determine a chain length if the body and cage just kinda float. what am i missing? BTW: running a 14-20 rear and a 34/38 front with a Simplex Competition suicide FD (maybe... cage clearance with Willaims cottered crankset arms will be real close), so chain wrap shouldn't be an issue.
Last edited by cocoabeachcrab; 03-23-22 at 12:47 PM.
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03-23-22, 01:08 PM
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Went through this myself recently. With the RD over the biggest cog and the chain threaded and draped over the chainring, I pulled the chain ends just taut and then removed two links and connected. Some sag in the smaller cogs, had to set the cage tension spring a couple of notches forward to give some extra pull in the smaller cogs. I had also adjusted the pivot spring a bit tighter. PITA but it actually shifts pretty well, surprisingly enough. This article at Classic Lightweights was helpful too: https://www.classiclightweights.co.u...nce-adjustment.
His tensioning method is different and probably works better than mine but I came out okay in the end. I usually go the subtractive route, easier to tighten by removing links than having to loosen by adding back in. The chain / RD threading is totally counterintuitive, being used to modern derailleurs it made me nuts - but it works. I'd note that I'm using a single chainring - you're using a double so that may add issues I didn't run into.
Here's a pic of my rig:
His tensioning method is different and probably works better than mine but I came out okay in the end. I usually go the subtractive route, easier to tighten by removing links than having to loosen by adding back in. The chain / RD threading is totally counterintuitive, being used to modern derailleurs it made me nuts - but it works. I'd note that I'm using a single chainring - you're using a double so that may add issues I didn't run into.
Here's a pic of my rig:
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Last edited by PilotFishBob; 03-23-22 at 01:16 PM. Reason: Added comment.
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03-23-22, 01:35 PM
#3
Myrtle Beach Crab
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Went through this myself recently. With the RD over the biggest cog and the chain threaded and draped over the chainring, I pulled the chain ends just taut and then removed two links and connected. Some sag in the smaller cogs, had to set the cage tension spring a couple of notches forward to give some extra pull in the smaller cogs. I had also adjusted the pivot spring a bit tighter. PITA but it actually shifts pretty well, surprisingly enough. This article at Classic Lightweights was helpful too: https://www.classiclightweights.co.u...nce-adjustment.
His tensioning method is different and probably works better than mine but I came out okay in the end. I usually go the subtractive route, easier to tighten by removing links than having to loosen by adding back in. The chain / RD threading is totally counterintuitive, being used to modern derailleurs it made me nuts - but it works. I'd note that I'm using a single chainring - you're using a double so that may add issues I didn't run into.
Here's a pic of my rig:
His tensioning method is different and probably works better than mine but I came out okay in the end. I usually go the subtractive route, easier to tighten by removing links than having to loosen by adding back in. The chain / RD threading is totally counterintuitive, being used to modern derailleurs it made me nuts - but it works. I'd note that I'm using a single chainring - you're using a double so that may add issues I didn't run into.
Here's a pic of my rig:
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03-23-22, 01:38 PM
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Also realized that some of what I wrote may not make sense as I had the cage and pivot springs pre-tensioned - seat of the pants flying and maybe just lucky that it turned out as well as it did for me. You may be better advised to go with the article link, and no doubt someone here has more coherent advice and probably experience with dual chainrings.
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03-23-22, 01:51 PM
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Crossed paths on your last post and mine there - I hope it works out without too much grief for you. Be prepared to exercise your 4 letter vocabulary though... 
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Pohl's law: Nothing is so good that somebody, somewhere, will not hate it.
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03-23-22, 03:01 PM
#6
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is the derailleur marked with the intended speed and chain width? They came in a variety of models.
03-23-22, 05:34 PM
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blahblahblah chrome moly
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It may actually be helpful to mount it incorrect-style to take a larger cog in back or if you need more chain wrap, like for multiple front rings. This is not from personal experience, just theorizing. I have seen them mounted incorrectly enough times to know it does work, after a fashion.
If you intentionally run the chain wrong, be prepared for every know-it-all to let you know!
Mark B
03-23-22, 06:19 PM
#9
Myrtle Beach Crab
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It may actually be helpful to mount it incorrect-style to take a larger cog in back or if you need more chain wrap, like for multiple front rings. This is not from personal experience, just theorizing. I have seen them mounted incorrectly enough times to know it does work, after a fashion.
If you intentionally run the chain wrong, be prepared for every know-it-all to let you know!
Mark B
03-24-22, 03:10 PM
#10
Senior Member
Start without the chain. Get the chainline right and most importantly get the resting derailleur wheels to line up perfectly with the big cog. Dialing in a later derailleur is easier with the limit screws, but they are yet to be thought of when this derailleur was designed.
