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Front Shimano derailler not shifting

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Front Shimano derailler not shifting

Old 05-23-14, 02:38 PM
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garimh
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Front Shimano derailler not shifting

I'm new to bikes and recently picked up a Cannondale R800 with Shimano gears from a local yard sale. The rear shifter is fine but the front shifter won't won't move the chain to the small ring in front. When I push the small left shifter, the derailleur only moves slightly but in the wrong direction i.e. it moves towards the big ring rather than going the other way and pushing the chain back towards the smaller ring. Essentially, the small left shifter seems to be doing the same thing that the large left shifter does.

If I manually move the chain to small ring, the large shifter moves it to large ring without a problem.

Any thoughts on how would I begin to sort out what the problem is?

Thanks.
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Old 05-23-14, 02:51 PM
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I don't know your exact setup, but you need to be aware that FDs can be sprung reversed from what you're used to.

In Bike speak, typical FDs -- sprung to move in -- are called "low normal". Sounds like you might have a "high normal" FD which moves out on the spring.

OTOH- if you're totally new to bikes you may simply not know that on most bikes the FD lever moves the derailleur out -- toward high, and the right lever moves the rear in -- toward low. In effect, both levers move toward bigger sprockets, but the direction and effect is the opposite. In other words, your bike is normal, but you're just no used to derailleur bikes.


Now, the rest is a matter of adjustment, and rather than type a treatise on the subject, I'll suggest you search tutorials on how to adjust a front derailleur. After you've reviewed a few and tried your hand at the job, feel free to come back for help over any stumbling blocks.
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Old 05-23-14, 04:13 PM
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Originally Posted by FBinNY View Post
I don't know your exact setup, but you need to be aware that FDs can be sprung reversed from what you're used to.

In Bike speak, typical FDs -- sprung to move in -- are called "low normal". Sounds like you might have a "high normal" FD which moves out on the spring.

OTOH- if you're totally new to bikes you may simply not know that on most bikes the FD lever moves the derailleur out -- toward high, and the right lever moves the rear in -- toward low. In effect, both levers move toward bigger sprockets, but the direction and effect is the opposite. In other words, your bike is normal, but you're just no used to derailleur bikes.


Now, the rest is a matter of adjustment, and rather than type a treatise on the subject, I'll suggest you search tutorials on how to adjust a front derailleur. After you've reviewed a few and tried your hand at the job, feel free to come back for help over any stumbling blocks.
Thanks. Although I'm still a bit confused. If I perhaps have a high normal as you say, how would I shift to the small front ring?

The right levers on the bike move the chain up and down the rear rings but do nothing for the front rings. So all the levers do what they supposed to, except for the left small one, which does nothing. I did search the forum but wasn't sure if my problem is really an adjustment problem so figured I'd post.

If it helps, it's a 1995 Cannondale R800 and according to Cannondale website, the front derailleur are "bottom pull/braze-on" type.

Thanks.
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Old 05-23-14, 04:20 PM
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Originally Posted by garimh View Post
Thanks. Although I'm still a bit confused. If I perhaps have a high normal as you say, how would I shift to the small front ring?

The right levers on the bike move the chain up and down the rear rings but do nothing for the front rings. .
The left lever controls the front shifter. Perhaps there's something wrong with yours, or the derailleur needs serious readjustment.

Try this.

Gently pull the bare wire away from the frame (left side) and observe if the front derailleur moves, and which way. If it does, repeat the test using the lever. Once you establish that the lever moves the derailleur, and which way, the rest is a matter of adjustment.
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Old 05-23-14, 04:33 PM
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Originally Posted by FBinNY View Post
The left lever controls the front shifter. Perhaps there's something wrong with yours, or the derailleur needs serious readjustment.

Try this.

Gently pull the bare wire away from the frame (left side) and observe if the front derailleur moves, and which way. If it does, repeat the test using the lever. Once you establish that the lever moves the derailleur, and which way, the rest is a matter of adjustment.
\

I gently pulled the wire from the frame to the left and the derailleur moved to the right, away from the bike. It does the same when I pull either the left large shifter or the left small shifter.
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Old 05-23-14, 05:02 PM
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Originally Posted by garimh View Post
\

I gently pulled the wire from the frame to the left and the derailleur moved to the right, away from the bike. It does the same when I pull either the left large shifter or the left small shifter.
What kind of shifter do you have. Specific model number and/or a photo would help.

Your mention of two levers, large and small on each side sounds like you might have a trigger system where the main lever pulls the lever, and the smaller lever allows it so slip back.

Is this how the right works? If so, the left should work exatly the same way.

So, try this next diagnostic.

Pull the bare wire away away from the frame enough to put some tension on it. Work the levers against this tension, and see if they work as intended -- big levers pulls, small lever allows some slip back.

If so, the levers are OK, and it's still an adjustment issue. Find a tutorial and follow through the rest.
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Last edited by FBinNY; 05-23-14 at 05:08 PM.
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Old 05-23-14, 05:11 PM
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The shifters are Shimano 105 STI Dual Control.
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Old 05-23-14, 05:26 PM
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Originally Posted by garimh View Post
The shifters are Shimano 105 STI Dual Control.
Yes, they are supposed to work as I described. But they require some cable tension to work properly. Do the test I described.
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Old 05-23-14, 06:43 PM
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Originally Posted by FBinNY View Post
Yes, they are supposed to work as I described. But they require some cable tension to work properly. Do the test I described.
Thanks. I put some tension on the cord and pulled the lever and the derailleur didn't really move at all.

Perhaps this is a more complicated fix than an adjustment and I don't want to waste too much of your time. Maybe better for me to stop by my local bike shop.

Thanks again though. I appreciate your help.
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Old 05-23-14, 06:56 PM
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Originally Posted by garimh View Post
Thanks. I put some tension on the cord and pulled the lever and the derailleur didn't really move at all.

Perhaps this is a more complicated fix than an adjustment and I don't want to waste too much of your time. Maybe better for me to stop by my local bike shop.

Thanks again though. I appreciate your help.
The bike shop may be where you need to be, but a question.

Not talking about the derailleur, but just the cable. When you applied some hand tension and worked the lever, did the cable move as it should, ie tighten with the paddle, and slacken with the escape (inner lever)?

The answer is key to whether the lever is working at all. If it works some but not well, spray something like WD-40 into the lever, and work it back and forth against hand tension. Shimano levers often fail because of dirt or dried grease. Soaking and working the mechanism can loosen the gunk and free them so they work right.
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Old 05-23-14, 07:31 PM
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Originally Posted by FBinNY View Post
The bike shop may be where you need to be, but a question.

Not talking about the derailleur, but just the cable. When you applied some hand tension and worked the lever, did the cable move as it should, ie tighten with the paddle, and slacken with the escape (inner lever)?

The answer is key to whether the lever is working at all. If it works some but not well, spray something like WD-40 into the lever, and work it back and forth against hand tension. Shimano levers often fail because of dirt or dried grease. Soaking and working the mechanism can loosen the gunk and free them so they work right.
When applying a bit of tension to the cable and working the large lever, the cable tightened straight away and released well. The small lever though, not so well. The lever moves freely but doesn't affect the cable tension until the lever is nearly at its end point so really not affecting the cable much at all. Maybe the cable just needs to be tightened? Or can it be tightened or adjusted for just the small lever if the large lever is fine?
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Old 05-23-14, 08:15 PM
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The lever sounds fine, but if you wish you can compare to the right.

The action and small levers is very different. look at the sketch below for reference. It's an analogy, not the actual lever.



The large lever pulls wheel B around winding cable up progressively until latch A drops in place. The small lever lifts latch A until it disengages allowing the derailleur return spring pull wheel B back one position when it drops back in and stops it.

So you feel cable movement directly with lever movement on the big lever, but won't feel any cable movement as the inner lever is moved, until it reaches to where the cable can slip back one position.

Now, if the lever is moving the cable, but the FD isn't moving right, then it's down to adjusting the FD, starting with cable length (tension).

It sounds like both the lever and FD are OK, though maybe some lube is called for, so it's tutorial time.
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Last edited by FBinNY; 05-23-14 at 08:25 PM.
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Old 06-01-14, 11:37 AM
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Finally had a bit of time to work on this. The lubing has helped and the derailleur is now moving back and forth freely but I have one last problem. The chain moves to small chain ring fine but when I try to shift from small to large, the chain moves to large ring only as long as I hold the shifter. As soon as I let go of the shifter, the derailleur moves back inward and brings the chain back with it back to the small ring.

I've been googling for this particular problem and can't seem to find the answer. Before I start fiddling with adjustment screws (and potentially messing this up), does anyone have any thoughts on what might be causing this?

Thanks!

Edit. I did see this post, which leads me to believe its a shifter problem. However, a heavy spraying of WD40 inside is unfortunately not fixing the problem.

Last edited by garimh; 06-01-14 at 11:52 AM.
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Old 06-01-14, 12:02 PM
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Very possibly a simple adjustment of limit screws. Check tutorials and youtube.
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