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Old 03-16-10, 10:53 AM   #1
corkscrew
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Suntour VX Front Derailuer. Can it handle a triple MTB crankset?

So I'm finally getting around to bring the frames in my garage out of hibernation. I have that 1980 Centurion Super LeMans I want to turn into a mtb-geared commuter.

It has a Suntour VX FD on it (found with the frame), can it handle a triple crankset?
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Old 03-16-10, 06:05 PM   #2
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(I was waiting for someone more knowledgable to weigh in, but until then, here goes.) AFAIK SunTour derailleurs intended for wide-range gearing had "GT" added to the name. There was a Vx GT, in fact. If your front derailleur cage is fairly similarly shaped on both sides, it was not intended to shift a triple. If the inner half is noticably closer to the chainring, it was intended to shift across a larger difference in teeth (greater capacity) - as in a triple. I have found that a cheap mountain derailleur shifts a triple far better than any road double front shifter. YMMV.
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Old 03-16-10, 06:43 PM   #3
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As far as I remember, the standard VX front derailleur will only handle a double, not a triple. The SunTour front derailleurs for triples usually had a longer cage, to accomadate the 3 chainrings.
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Old 03-16-10, 09:15 PM   #4
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My Suntour Vx (not labeled a GT, I was under the impression that that only applied to rear derailleurs) shifts a 52-47-36 triple, not stupendously, but it works.
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Old 03-17-10, 02:35 AM   #5
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hatbeardglasses, you are probably correct about GT only reffering to the RD. BTW, "Not stupendously" is how my AR shifted a triple. An old XCD works perfectly.
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Old 03-17-10, 10:31 AM   #6
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Thanks for the info guys. Seeing how I have it already I'll give it a try. I haven't looked closely at my donor mtb yet, but I'm sure the large ring is less than 52.

I already have a V-GT RD I'm going to be using, and would like to keep the drive train all Suntour, if only for a sense of self satisfaction.
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Old 03-17-10, 10:37 AM   #7
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I used my Suntour Vx FD to shift a 48-38-28, which it manages to do (I assume not particularly well, but I have never used a FD designed for triple). I just have to be careful to not try to shift to the small ring under any sort of load or else it will either not shift or the chain will hop right off.
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