Derailleur replacement

tunamikebike

tunamikebike

Member
I wanted to change the rear derailleur on my 12 year old bike. It's an 8 speed Shimano Alivio. Unfortunately, they are made not anymore. But I understand you can use a 9 speed derailleur with the 8 speed shifters and everything will work fine. So I bought a 9 speed Shamino Alivio (RD-T4000-SGS), and it doesn't work with the old shifters. The "B" screw was in the correct position on the derailleur hanger. I don't want to use a product that is lower than the Alivio. I ended up putting the old derailleur back on, everything works fine - but I would like to know what I did wrong.
 
Nine is a little different. If everything is perfect, the issues would be minimal, but it is different.

8 speed is changing to "Essa", which is why you may be having trouble finding stuff. That said, there's almost bound to be old stock about.

Altus (the "Mega Range" derailleur you see on all the 7 speed freewheel bikes) works fine with 8 speed. It's an 8 speed bike, don't overthink it 👍
 
tunamikebike said:
I wanted to change the rear derailleur on my 12 year old bike. It's an 8 speed Shimano Alivio. Unfortunately, they are made not anymore. But I understand you can use a 9 speed derailleur with the 8 speed shifters and everything will work fine. So I bought a 9 speed Shamino Alivio (RD-T4000-SGS), and it doesn't work with the old shifters. The "B" screw was in the correct position on the derailleur hanger. I don't want to use a product that is lower than the Alivio. I ended up putting the old derailleur back on, everything works fine - but I would like to know what I did wrong.
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What wasn't working? Wouldn't shift properly or wouldn't go into high/low gears?
 
Also why did you want to change the 8-speed derailleur?

If it's 12 years old, is the chain new or have you checked how worn it is?
 
It's my wife's bike and it doesn't get used very much. I replace the chain every two years but haven't done the cassette or the crank sprockets (they look good). It would shift only one gear and not reload for another shift.
 
@tunamikebike it's largely positioned as an OEM product, and I've only seen one bicycle with it, so I can't tell you. It would probably work okay, though, as long as you don't exceed the chain wrap capacity.
 
tunamikebike said:
It's my wife's bike and it doesn't get used very much. I replace the chain every two years but haven't done the cassette or the crank sprockets (they look good). It would shift only one gear and not reload for another shift.
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Not reloading seems like it's a cable routing issue to me. Are you sure the cable was in the correct position on the derailleur? I've definitely had issues like this where the cable route isn't totally clear.

If you disconnect the cable can you push the derailleur into all the gears?
 
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