I would like to upgrade to 8 speed. Does the Shimano Tourney TX rear derailleur support an 8-speed cassette.
asked Sep 21, 2015 at 23:29
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1Can you expand on why you want to upgrade to 8 speed? You might get the same effect from a replacemant cassette with slightly wider spacing - I went from a 5 speed to a 7 speed and needed many replacement parts.– Criggie ♦Sep 22, 2015 at 1:54
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3 Answers
Any Shimano 7-9 speed rear derailleur will work with any 7-9 speed Shimano shifter. To upgrade to 8 speed, you need an 8 speed Shimano-compatible cassette or freewheel which works with your rear wheel, 8 speed shimano shifters, a 7-9 speed Shimano rear derailleur and a Shimano road front derailleur if you have road shifters or a Shimano mountain front derailleur if you have mountain shifters.
The rear derailleur needs to have appropriate capacity and sprocket size tolerances for the gearing you want to run, and the front derailleur has to be matched to the number of chainrings, size of the jumps between chainrings and chainring sizes. Both have to have apppropriate mounting as well, obviously (tourney comes with a claw adapter in some cases; most modern frames don't need it).
So, yes, you can use a Tourney rear derailleur with a Shimano 8 speed shifter, but you have to make sure the rest of the components work. That being said, upgrading from 6 or 7 speeds to 8 speeds usually doesn't improve anything (esp. with low quality parts like Tourney).
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Correct me if I'm wrong, but I seem to recall that 7 speed cassettes are a different width than 8 speed cassettes. If that's right, a bigger concern than the derailleur would be the hub. Then again, it's been a while since I've worked with a 7 or 8 speed and I could be misremembering.– jimchristie ♦Sep 24, 2015 at 1:25
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@jimirings you are correct - 6/7/8 speed cassettes are different widths. However they (generally) have the same spacing between gears, and the same chain will work in 6/7/8 . So I put a 7 speed cassette on an 8 speed freehub and needed to fit 3.5mm of spacer rings, which can be purchased from any LBS for a couple of dollars. They go on the freehub first, befor the cassette and should allow the cassette lock ring to go on at the correct height. It should be 4.5mm of spacers per gear, but I had some rivet heads in the way.– Criggie ♦Sep 24, 2015 at 1:58
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@jimirings - Generally 7 speed freehubs won't fit 8 speed cassettes but the other way works fine. As for freewheels, it depends on the spacing.– BatmanSep 24, 2015 at 3:33
I have a Shimano Tourney 6/7 speed that works on a 8 speed cassette with Altus shifter. This comes stock with the bike. If you search online, there are folks that tried with a 9 speed cassette and it worked for them. As always, YMMV with the shifter you use, and I suggest you check your combination online first before taking the plunge. Or if you have spares in your parts bin, you could always strap them on and try.
[Update 20 Mar 2021]: I have a friend who bought a cheap Raleigh bike that runs a 10-speed cassette with a Tourney 6/7 speed rear derailleur with a 10-speed MicroNew shifter, stock. It worked without any issues so far after more than a year. I don't know what black magic that was!
I am currently using a Shimano Tourney TX RD on my old mountain bike that has 8 speed casette, no problem in either shifting response and performance.
