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New Rear Derailleur: Middle gears feel 'off'

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New Rear Derailleur: Middle gears feel 'off'

Old 03-15-10, 11:50 AM
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New Freewheel: Middle gears feel 'off'

I own a Trek 820, about 5-10 years old (purchased used). It was time recently to replace the chain and freewheel, so I did that with a bit of assistance from my local bike shop. I replaced it with a shimano freewheel (7 speed to match the old freewheel). Also replaced the rear derailleur shifter cable, since it snapped around the same time. Adjusted the derailleur pretty well, and everything seemed to shift smoothly, with a small amount of resistance to shifting up (no matter how much I released cable tension).

When I took the bike for a spin on my commute, the 4th, but especially 5th gears didn't quite feel like they were sitting right. This feeling was amplified when biking up a hill. I can't describe the sound, but it definitely sounded like the chain was having some issues with the cogs it was on. All other gears were fine. The 4th/5th gears worked, but it did not emulate a smooth ride. After tweaking the derailleur cable some more, I was still having trouble.

Two things I noticed: The freewheel has a slight wobble to it. The rest of the tire is fine, including the hub - it's limited to just the freewheel. From everything I've read online, this sounds like it's normal. The other thing that came up recently is that the rear shifter lever for up-shifting doesn't snap back in to place too easily once it's been depressed.

This is my first real venture into bicycle maintenance so I'm not too familiar with what might be causing this. Hopefully it's something as simple as needing to tweak the cable tension even more... Thanks for any suggestions you're able to provide.

Last edited by TimS; 03-15-10 at 12:11 PM.
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Old 03-15-10, 04:40 PM
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The freewheel wobble is normal (within reason) and your old one probably wobbled too but you didn't notice. From your description, especially because the lever isn't returning crisply I guess that your problem likely stems from cable friction.

A few possibilities come to mind, especially if you replaced only the inner wire, and continued using housing more than a few years old. Either you need to lube the cable better, or the inner liner of the housing is worn through in the places of highest friction, or the housing is trying to pull through the ends of the ferrules and pinching the ends closed a bit.

There's an easy test to see where cable friction might be the cause. You'll need a repair stand, trainer, ropes strung from pipes,or patient friend to hold the bike up with the wheel off the floor.

Shift the bike to the last gear outside of the problem sprockets and make sure it's trimmed perfectly and pedals smoothly. Now leaving the lever alone, shift one gear by pulling the wire form the frame and using hand touch trim the RD as well as you can, then while still pedaling release the wire and the RD should shift back and trim correctly. Repeat this moving over one gear inward until you've checked each of the middle sprockets both as the high and low choice.

If the RD is working fine this way, but not with lever control, it's either the lever or cable forward of the down tube, if it's sticky or doesn't shift back crisply here, it's either the last loop of housing or something in how the RD itself is set up, possibly the jockey wheel being too close to the middle sprockets among other possibilities.

You can also check the lever in a similar way by parking the RD up on the largest sprocket and without pedaling shift the lever against hand tension on the cable at the downtube, though it helps if you know from experience how it should feel.

Lastly, consider that after riding a well broken-in drivetrain for a long time it's possible that you're oversensitive to the feel of new components that need to be ridden a bit.
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Old 03-16-10, 01:27 PM
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Make sure the derailleur hangar is aligned correctly.
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Old 03-16-10, 02:58 PM
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Originally Posted by yak
Make sure the derailleur hangar is aligned correctly.
+2

Take it to a shop and have it checked. Shouldn't cost more than $15 to fix it if it's bent.
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