Rear Mountain Bike Derailleurs
Can I fit a Shimano Deore 9 speed rear derailleur on a bike originally equipped with a Shimano Altus 7 speed?
I have a Schwinn mountain bike originally equipped with Shimano Tourney/Altus parts. The rear derailleur is a 7 speed Shimano Altus, and I would like to make a cheap upgrade for some trail riding (recently got into it and the rear shifter is slow, even when tuned) by changing this out for a better Shimano Deore rear deraillleur. I know that 8 and 9 speed derailleurs are compatible with 7 speed cassettes, but will the Deore derailleur fit properly and work as intended in my case? Do I need any special tools besides a chain tool and some wrentches/allen keys/screwdrivers?
Alright… first off, you can change it. Second, you will only need to change your chain if you change your cassette. All you need to do is adjust the limit screws on the derailler to fit the 7 speed cassette.
The gear spacing is different between 7 and 9 speed, but this is controlled by the shifter, not the derailler. If all you are changing is the derailler, it is no problem.
If you don’t want to break the chain, you can install a rr derailler by removing the lower pulley, loosening the upper pulley, and re-installing the lower pulley on the chain after routing it through the derailler. It is really easy and quick this way.
Lastly, if you do choose to make the drivetrain 9 speed, you’ll need to replace the rr wheel, chain, and shifter.
Good luck
6 – Advanced Rear Derailleur Adjustment
