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  1. #1
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    Front derailer issue

    So I took my first real ride today...prior to this I had done a couple of 10 mile runs but on very flat routes. This one was through Worcester, MA and anyone that knows it, knows that it's hilly though I wouldn't say my route was particularly so. I rode to my gym, worked out and rode back. A 10.25 mi loop separated by 60 minutes of circuit training and 45 minutes of cardio (that might have been a mistake). My average was just over 12mph but I was slowed by a front derailer issue. The cable had snapped while on vacation and I took it to my LBS to have it replaced, it shifted fine the first couple of times and then it would take it's time if it went to the outer chainring at all. The derailer didn't move and I'm wondering if it's as simple as a stretched cable. Retensioning looks like a breeze, any thoughts? We just got a bike trailer and were going to take spartan113 out for a ride Sunday.

  2. #2
    Senior Member Caincando1's Avatar
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    If you want to do it yourself, there are a couple good websites for DIY bike repair. Otherwise take it back to the LBS that fixed it and make them fix it, becasue it sounds like they didn't do something right.
    2006 Trek Pilot 1.0
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  3. #3
    Weekend Warrior
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    If you think you can do it, google up some resources and try your hand at it. Its a simple machine, as long as your careful and don't push anything REALLY hard and break it, there shouldn't be any problem with trying. The worst you'll do is make it worse. The LBS wont laugh at you too much if you take it in after trying to fix it, they might even show you were you went wrong.

    That being said, its pretty simple. The rear one can be a little tricky, but the front derailer is cake to adjust.

  4. #4
    Enjoying the Ride Bob Loblaw's Avatar
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    Hey Spartan-
    Adjusting a FD is REALLY simple! Granted, you can probably get the LBS to fix it for free, but if you want to know how to dial it in yourself, read on.

    There are two ways to adjust a FD. There are two small screws called 'limit screws' on the top of the derailleur. They control how far the FD swings in each direction. The FD rocks inward until it hits the "LOW" limit screw and it rocks outward until it hits the "HIGH" limit screw. You want the chain to be centered in the FD cage, and parallel with the cage when the FD is at each of the 3 (or 2) chainrings on the crank. Those limit screws adjust the maximum travel of the FD in each direction. Use a screwdriver, and turn one while you watch the derailleur. You'll slowly see it travel in one direction. If you look closely at the FD, it should become clear how it works. After you're done playing, put the limit screws back where they were when you started. If you simply had a cable replaced, it's unlikely that the shop moved them.

    The other way to adjust a FD is by varying the tension of the shift cable. The cable pulls on the FD when you move the shifter to shift to a larger chainring, you're pulling on the cable, and pulling against a strong spring in the derailleur. When you want to shift back down to a smaller chainring, you're releasing an amount of cable, and the spring pulls it back and allows the FD to move. If there is not enough cable tension, when you go to shift upwards to a larger chainring, there simply isn't enough travel to get the FD into a position where the chain will grab that larger ring. If there is too much cable tension, the FD will tend to not shift down to a smaller ring easily. This is because the spring in the FD must swing from it's own internal spring. Too much cable tension works against that spring, and doesn't allow the FD to swing fully.

    It sounds to me like you don't have enough cable tension in your FD shift cable. There are usually a couple of simple ways to fix this.
    1. Follow the FD shift cable along the frame. You should see a boss brazed onto the frame somewhere with a 'barrel adjuster' on it. This adjuster can be screwed in and out. By screwing it out, you're essentially pulling on the cable and increasing the tension.

    2. Sometimes, depending on your bike, you may have a similar adjuster near the shift lever. Again, backing out this adjuster ends up pulling on the cable making it tighter.

    3. Lastly, you could also loosen the screw that clamps the cable in the FD. Loosen this screw, pull the cable tight, then retighten the screw. This is more of a pain in the butt because it's tough to make precise tension adjustments this way. Option 1 is your best bet.

    Put your bike on some kind of stand to get the back tire off the ground. If you don't have a stand, ut it on a crate, hang it from the rafters, whatever. Try adding some cable tension, a little at a time, and spin the back wheel. While pedaling the back wheel, try to shift up and down the front chainrings. This is usually an iterative process of adding some tension, checking the shifting, adding tension, checking, adding, checking, letting some tension out, checking... you get the idea.

    I've found that these tasks go much smoother with some type of radio playing in the background, and a cold beer close by.

    Good luck!

  5. #5
    Senior Member Bill Kapaun's Avatar
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    The cable MIGHT have just stretched a bit. Quite normal!
    You can probably just give the adjuster a turn (give or take).

    http://sheldonbrown.com/derailer-adjustment.html
    http://www.parktool.com/repair/byregion.asp?catid=53

  6. #6
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    I played with it a bit tonight without a ton of success. Here's the thing, with the wheel in the air it shifts easily from chainring to chainring. As soon as I get on it and try to shift while riding I get nothing. I'll try to find the barrell adjustment tomorrow morning if I don't succeed it's off to my LBS to get them to adjust it.

  7. #7
    Clyde Racer. .Cole's Avatar
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    This is what you do to keep your FD in tension the first thing you do when you install the new cable is shift it down into the bottom ring. Pull is as tight as possible then clamp down the screw (should be a metric 5). Now while NOT pedaling try to shift up as much as possible, this will pre stretch the cable. This is the best way to keep yourself for having to adjust it mid ride. I learned this about 6 months into wrenching, and had many less come in for Der. adjustments after cable replacements. I have been wrenching for 4 years on other peoples bikes and 7 years on my own. If you have any questions about anything feel free to shoot me a PM.

    Cole.

  8. #8
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    I fixed the derailer via the limit screws at the top of the clamp that holds it in place. Once I got it shifting to the outer chainring it didn't want to shift back so a little tinkering and the problem was resolved. One thing I noticed was that the derailer was not precisely parallel to the chain so I readjusted that as well. All in all it was a fun little DIY day as when I got the bike from the basement I found a flat front tire so I got to change a tube for the first time in 17 years or so. Yippee...now I have well earned beer in hand. Tomorrow the wife and I take Spartan113 up to the Nashua River Trail.

  9. #9
    Enjoying the Ride Bob Loblaw's Avatar
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    Quote Originally Posted by Spartan112 View Post
    I fixed the derailer via the limit screws at the top of the clamp that holds it in place. Once I got it shifting to the outer chainring it didn't want to shift back so a little tinkering and the problem was resolved. One thing I noticed was that the derailer was not precisely parallel to the chain so I readjusted that as well. All in all it was a fun little DIY day as when I got the bike from the basement I found a flat front tire so I got to change a tube for the first time in 17 years or so. Yippee...now I have well earned beer in hand. Tomorrow the wife and I take Spartan113 up to the Nashua River Trail.
    Great Spartan! I'm glad you were able to figure it out... Kind of fun, eh?

  10. #10
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    Yup and it worked swimmingly on the ride yesterday.

  11. #11
    Senior Member Bill Kapaun's Avatar
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    I always do my final adjustments when riding. Run it through all the gears, front & back, a couple times.

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