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Old 09-11-12, 09:53 PM   #1
nolken
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Older double 8 speed double crankset causing shifting problems with triple shifter

Okay so when I did my bike build i just picked up a cheap Dura Ace FC-7402 double 8 speed crankset, mainly to get me by until I could upgrade. I'm currently using Shimano ST-5603 shifters, which are 3x10. I'm having problems shifting properly. My rear shifter is perfect, no problems what-so-ever. I was under the impression that the triple shifter would work fine with the double crankset. My front derailleur is the FD-5500. My problem is that the front derailleur won't shift far enough to actually make the chain switch chainrings. The indexed positions of the shifter are too small to move the derailleur far enough.

Is there something I might be doing wrong? Are triple cranksets spaced a little closer together than the doubles or are newer 10 speed cranks closer than the older 8 speed?

I don't really want a triple crankset, I just got a really good deal on the shifters, that is why I got the triple shifter.
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Old 09-11-12, 10:16 PM   #2
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with the front derailleur cable disconnected completely, is the high and low limit screws set properly for no rubbing? What I mean is when the front cable is disconnected, is the front derailleur adjusted properly so that the cage doesn't rub on the chain when you have the bike up on the stand and you spin the pedals?

You need to start at the basics. Get the cage adjusted properly. It also almost sounds like to me that the high screww is set in such a way that it isn't allowing the front derailleur to swing all the way out to allow the proper shifting to the large ring.
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Old 09-11-12, 10:17 PM   #3
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You can use a triple shifter no problem with a double crankset. I'm using a triple ultegra on my road bike with a double front and it works fine. When the high limit screw is set properly, it locks out the middle to large ring position on the shifter.
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Old 09-11-12, 10:20 PM   #4
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To answer the last first, the chainrings on 10s cranksets are closer together than 9s, and much more than 8s. The much more is relative to what's involved, so might only be a bit over 1mm.

Since the rings are closer the FD travel for 10s index is also less. Here's something you might try. Since your lever is a triple, set the outer ring first to shift and trim correctly with the outermost lever position. Then double shift for the inner, using the limit screw to set the inner trim position. This will give you a fair amount of cable slack on the inner, but double shifting back and forth would give you decent functionality.

Another trick that might buy you a bit of added travel, and spare you the double shift routine is to toss out the manual, and intentionally make a common mistake. Attach the cable to the opposite side of the screw (toward the fulcrum). (sequence = pinch bolt-cable-FD arm-fulcrum) This chokes up on the lever increasing the travel for the same cable movement. It usually gets you about 10-15% more travel, so it's dicey whether it's enough, but worth a shot.
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Old 09-11-12, 10:24 PM   #5
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yeah the limit screws are set properly. the problem is when i shift over once it isn't enough to shift to the larger chainring. then if i try to shift to the third it wont lock because of the limit screws, so it will shift then revert back to the smaller chainring i've adjusted the tension and i spent about 2 hours on it tonight trying to adjust it so that it would work. no luck.
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Old 09-11-12, 10:31 PM   #6
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Quote:
Originally Posted by nolken View Post
then if i try to shift to the third it wont lock because of the limit screws, so it will shift then revert back to the smaller chainring i've adjusted the tension and i spent about 2 hours on it tonight trying to adjust it so that it would work. no luck.
Read the post above and set the cable for correct trim in high position and outer ring. That'll let you double shift for then inner letting the limit set the inner trim. Overly tight cables don't work, but excess slack isn't a problem (except that it may "ting" against the frame on bumps)
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Old 09-11-12, 10:33 PM   #7
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Quote:
Originally Posted by FBinNY View Post
To answer the last first, the chainrings on 10s cranksets are closer together than 9s, and much more than 8s. The much more is relative to what's involved, so might only be a bit over 1mm.
That's makes perfect sense as to why this is happening. I didn't get a strait forward answer on this searching the forums. thank you.
If I did get a new 10 speed crank would that more than likely solve the problem?

Quote:
Originally Posted by FBinNY View Post
Since the rings are closer the FD travel for 10s index is also less. Here's something you might try. Since your lever is a triple, set the outer ring first to shift and trim correctly with the outermost lever position. Then double shift for the inner, using the limit screw to set the inner trim position. This will give you a fair amount of cable slack on the inner, but double shifting back and forth would give you decent functionality.

Another trick that might buy you a bit of added travel, and spare you the double shift routine is to toss out the manual, and intentionally make a common mistake. Attach the cable to the opposite side of the screw (toward the fulcrum). (sequence = pinch bolt-cable-FD arm-fulcrum) This chokes up on the lever increasing the travel for the same cable movement. It usually gets you about 10-15% more travel, so it's dicey whether it's enough, but worth a shot.
These are both very good ideas. I will definitely try them for the time being until I can get a new crankset. These i'm sure will work a lot better than what i'm doing now.
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Old 09-11-12, 10:35 PM   #8
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Originally Posted by nolken View Post
If I did get a new 10 speed crank would that more than likely solve the problem?

.
Yes, when you go to 10s cranks the spacing will match the throw of the 10s levers and things will work as designed. Until then you have to out think the system.
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Old 09-11-12, 10:40 PM   #9
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Awesome! I can deal with some slack in the cable to finally get some consistent shifting! Thank you sir
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