9 gear derailleur on 8 speed bike
07-02-20, 11:07 AM
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9 gear derailleur on 8 speed bike
I have an 8 speed cassette in the back, bought a 9 speed rear derailleur - I plan on using a single crank with an 8 speed shifter. By doing this will the 9 spd derailleur work ok?
Thank you!
Thank you!
07-02-20, 11:42 AM
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"Speeds" are in the shift lever clicks , not the rear derailleur
9 speed cassettes are about as wide as 8 speed , Just the spaces between them are thinner to add that 1 cog.
9 speed cassettes are about as wide as 8 speed , Just the spaces between them are thinner to add that 1 cog.
07-02-20, 11:57 AM
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Shimano? No issue. "May" have an possible issue with the 8 speed chain and cage width but running a narrower 9 speed chain would solve that.
07-02-20, 12:23 PM
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No problem with chain width on 9sp RD with 8 speed chain. I run 9 speed RD’s with 7 and 8 speeds with 8 speed chain.
I always hear how Shimano narrowed cages and haven’t found anything to support it. This thread got me to measure the cages of 8 and 9 speed RD’s. Both are 9mm +/-. Measured a 9 speed XT that was slightly wider than an 8 speed XTR. Now there maybe some that are narrower.
That said, an older 6/7 speed Deore measured 10.5mm +/-.
Maybe 10/11 speed, but not 8 to 9.
John
I always hear how Shimano narrowed cages and haven’t found anything to support it. This thread got me to measure the cages of 8 and 9 speed RD’s. Both are 9mm +/-. Measured a 9 speed XT that was slightly wider than an 8 speed XTR. Now there maybe some that are narrower.
That said, an older 6/7 speed Deore measured 10.5mm +/-.
Maybe 10/11 speed, but not 8 to 9.
John
07-02-20, 02:16 PM
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Many years ago, I upgraded one of my bikes from 7 speed to 9-speed. The derailleur was the only component that I didn't change.
07-02-20, 02:48 PM
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I have an XTR derailleur of unknown origin hooked to an 8 speed rapid rise trigger shifter.
No issues
No issues
07-02-20, 03:38 PM
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I used a 9 spd. rear derailleur on my 8 spd. commuter bike for 8 years. I ran a 11/34 8 spd. cassette (lots of hills), with a Shimano Deore rear derailleur. Never had any problems with it. I also has a 46/36/26 crankset.
Last edited by Doug64; 07-02-20 at 05:51 PM.
07-03-20, 06:19 AM
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Thanks guys for your quick replies. So, I will keep the 8 speed cog and put the 9 speed DR on with a 9 speed chain. IF I keep the 3 gear crankset, will that work out? What shifters should I buy? Just use the existing 8 speed shifter so it never wants to go to a ninth gear?
07-03-20, 07:57 AM
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Thanks guys for your quick replies. So, I will keep the 8 speed cog and put the 9 speed DR on with a 9 speed chain Your existing 8 speed chain should work fine unless you felt it needed replacement anyway. IF I keep the 3 gear crankset, will that work out? If your new 9s RD has the correct cage length to handle the chain wrap needed for a triple crank.What shifters should I buy? Unless there is something wrong with your current shifters there is no need to replace them. Just use the existing 8 speed shifter so it never wants to go to a ninth gear? There is no 9th gear if you're using a 8 speed cog and shifters. The RD doesn't know what speeds it's being used on or care. The shifter controls # of speeds. I run a 9 s RD on my daughters 6 speed bike.
See above
07-03-20, 08:02 AM
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Thank you! The DR is a Shimano Deore RD-M592-SGS. I imagine the cage length will be adequate? What chain length would be appropriate if I go single crank?
Last edited by Chefs20; 07-03-20 at 08:12 AM.
07-03-20, 08:21 AM
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07-04-20, 10:01 AM
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Thanks guys for your quick replies. So, I will keep the 8 speed cog and put the 9 speed DR on with a 9 speed chain. IF I keep the 3 gear crankset, will that work out? What shifters should I buy? Just use the existing 8 speed shifter so it never wants to go to a ninth gear?
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Stuart Black
Plan Epsilon Around Lake Michigan in the era of Covid
Old School…When It Wasn’t Ancient bikepacking
Gold Fever Three days of dirt in Colorado
Pokin' around the Poconos A cold ride around Lake Erie
Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
