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Front Derailleur Question

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Front Derailleur Question

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Old 12-11-04, 02:29 PM
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slowpedal53
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I purchased a NOS Shimano RX100 front derailleur for the bike I'm rebuilding. I am using the old double crankset and a new identical replacement for the bottom bracket.

Right out of the box, the cage doesn't extend out far enough, falling a few mm shy of the large chainring. I tried adjusting the H screw but nothing happens. (On my old derailleur, the limit screws move a cam and you can adjust the reach easily, on or off the bike.)

From what I read on the Park Tool site, it seems as if I have to have the derailleur cabled up and under tension to make this adjustment. Am I reading this correctly? Does anyone know of any reason this derailleur won't work?

Also, my old derailleur had a built-in cable stop that the new one doesn't have. I get the feeling this will be a problem. Any advice?

Thanks.
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Old 12-11-04, 04:38 PM
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sydney
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Originally Posted by slowpedal53
I purchased a NOS Shimano RX100 front derailleur for the bike I'm rebuilding. I am using the old double crankset and a new identical replacement for the bottom bracket.

Right out of the box, the cage doesn't extend out far enough, falling a few mm shy of the large chainring. I tried adjusting the H screw but nothing happens. (On my old derailleur, the limit screws move a cam and you can adjust the reach easily, on or off the bike.)

From what I read on the Park Tool site, it seems as if I have to have the derailleur cabled up and under tension to make this adjustment. Am I reading this correctly? Does anyone know of any reason this derailleur won't work?

Also, my old derailleur had a built-in cable stop that the new one doesn't have. I get the feeling this will be a problem. Any advice?

Thanks.
When mounted on the seattube, the derailer can be moved by hand to see how much throw it has.There is no cam,just stops on the hi and low side. The low side is controlled by the spring,and low limit screw as a stop.And with the hi limit all the way out, if you cant get enough throw, by moving the derailer by hand,there is a compatibility problem..And yeah, a lack of a casing stop is a problem. You can probably use a clamp on stop on the downtube,but that will aslo probably require drilling a hole in the BB shell and installing a cable guide.
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Old 12-11-04, 11:11 PM
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slowpedal53
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Originally Posted by sydney
When mounted on the seattube, the derailer can be moved by hand to see how much throw it has.There is no cam,just stops on the hi and low side. The low side is controlled by the spring,and low limit screw as a stop.And with the hi limit all the way out, if you cant get enough throw, by moving the derailer by hand,there is a compatibility problem..And yeah, a lack of a casing stop is a problem. You can probably use a clamp on stop on the downtube,but that will aslo probably require drilling a hole in the BB shell and installing a cable guide.
Thanks. I'll mount it up and try moving it again. If there's a compatibility problem, is that caused by an unusually long BB spindle, or is there something else?

I have a clamp-on stop I can use. There's a cable guide brazed on to the top of the BB shell on this frame.
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Old 12-12-04, 09:06 AM
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Originally Posted by slowpedal53
Thanks. I'll mount it up and try moving it again. If there's a compatibility problem, is that caused by an unusually long BB spindle, .....
Probably
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