geofflowery
11-13-02, 08:57 PM
I have an 18-speed road bike and I love it, but there is one problem with it. I can't seem to get it to shift onto any other chain ring than the big one of the three on the front derailleur. Any suggestions??
Bicycle Mechanics - Problems Shifting
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John E
11-13-02, 09:19 PM
When you attempt to downshift the front, does the cable go slack? Make sure the front derailleur and its control cable can move freely.
geofflowery
11-14-02, 12:11 AM
Actually yes, the cable does go slack. Is there a specific part that I need to tighten or is there something else that can be done?
D*Alex
11-14-02, 05:44 AM
Yes-you need to tighten the cable at the derailleur. If how you do this is not obvious, then buy a bike repair book.
:rolleyes:
:rolleyes:
Ed Holland
11-14-02, 06:38 AM
Hi Geoff
Lets have a look at the mechanics of your problem anyway. The Front derailleur (in all the types I have seen) moves toward the larger chainrings, outward from the frame, as the cable is pulled tighter by the shifter. Slackening the cable by action of the shifter allows the derailleur to move towards the frame, and to the smaller chainring(s). The derailleur mech has a spring built into it that allows it to relax to the smaller chainring positions when the cable is slackened. From the above posts, it seems like your shifter is ok - the cable slackens - but the mech is refusing to shift the chain. There are a number of possible reasons of this;
1 Derailleur is stuck due to dirt and or lack of lubrication
2 Cable is trapped or sticking somewhere (perhaps where it leads under the bottom bracket)
3 The return spring inside the derailleur is weak/broken
4 Somehow the limit screws on the mech have been adjusted so that shifting is prevented (unlikely)
To start with, I'd suggest playing with the shifter to see if any movement in the derailleur can be observed. A clean up, if necessary, and a drop of oil on the pivot points of the mech would not hurt it. Also trace the cable along its length to see if it is the cause of the problem. If you are unsure about tinkering with this, it sounds like an easy job for the bike shop
Ed
Lets have a look at the mechanics of your problem anyway. The Front derailleur (in all the types I have seen) moves toward the larger chainrings, outward from the frame, as the cable is pulled tighter by the shifter. Slackening the cable by action of the shifter allows the derailleur to move towards the frame, and to the smaller chainring(s). The derailleur mech has a spring built into it that allows it to relax to the smaller chainring positions when the cable is slackened. From the above posts, it seems like your shifter is ok - the cable slackens - but the mech is refusing to shift the chain. There are a number of possible reasons of this;
1 Derailleur is stuck due to dirt and or lack of lubrication
2 Cable is trapped or sticking somewhere (perhaps where it leads under the bottom bracket)
3 The return spring inside the derailleur is weak/broken
4 Somehow the limit screws on the mech have been adjusted so that shifting is prevented (unlikely)
To start with, I'd suggest playing with the shifter to see if any movement in the derailleur can be observed. A clean up, if necessary, and a drop of oil on the pivot points of the mech would not hurt it. Also trace the cable along its length to see if it is the cause of the problem. If you are unsure about tinkering with this, it sounds like an easy job for the bike shop
Ed
pokey
11-14-02, 06:45 AM
Try www.parktool.com for how to on front derailers.
pokey
11-14-02, 06:48 AM
Originally posted by D*Alex
Yes-you need to tighten the cable at the derailleur. If how you do this is not obvious, then buy a bike repair book.
:rolleyes: Well actually,if the cable were loose,he would not even be able to shift to the big ring would he?:rolleyes:
Yes-you need to tighten the cable at the derailleur. If how you do this is not obvious, then buy a bike repair book.
:rolleyes: Well actually,if the cable were loose,he would not even be able to shift to the big ring would he?:rolleyes:
geofflowery
11-14-02, 02:39 PM
Alright, thank you guys for your help! I'll try those out today. Hopefully that's all I need to do.
geofflowery
11-17-02, 08:28 PM
I just wanted to thank you guys for the tips on the derailleur. I went to parktools.com and that was a very helpful sight. It seems to answer most questions that a newer rider like myself might have. Anyway who's had a problem with their bike should check out their website if they aren't sure how to fix a problem. Thanks again guys.