9 speed shifter w/ 8 speed cassette ?

Discussion in 'The Workshop' started by mtbdad, Apr 28, 2009.

  1. mtbdad

    mtbdad Member

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    Im looking to upgrade my wife's mtb from 8 speed to 9 speed. Can I replace the sram x4 shifters with a sram 9 speed shifters now and use the 8 speed cassette ?

    Or do I need to replace the 8 speed cassette at the same time ?
     
  2. b3rnard

    b3rnard Member

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    9 speed shifter will work just fine on an 8 speed cassette. Save your self the trouble and do it all at once, if you plan on doing a 9 speed cassette later on.

    You don't really benefit from just replacing the x-4 shifters now, if you don't have a 9 speed cassette/derailleur.
     
  3. jeffj

    jeffj Bloated Mountain B'hiker

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    No. A 9 speed shifter will NOT work with an 8 speed cassette.

    The spacing between gears is narrower on a 9 speed. The 9 speed cassette will fit onto the hub the 8 speed came off of though, so if you replace the shifters, chain and cassette with 9 speed stuff, you'll be good to go. The cranks, front derailleur and rear derailleur will work with either.
     
  4. b3rnard

    b3rnard Member

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    I trade between an 8 and 9 speed cassette, depending on trail/riding conditions, what gearing is best suited for it. It works #-o

    The spacing you are referring to is marginal difference.
    Most 9 speed shifters are '8/9 speed compatible', same goes for the rest of the drive train (if it'9 speed it will work 1 speed down). Ever wonder why SRAM and Shimano are interchangeable?

    The key is the shifter and derailleur must both have 1:1 actuation. That is what indexed shifters are all about. The .6 mm difference in spacing between 8 and 9 speed cassettes can be compensated for by a few turns (+/-) of the barrel adjusters on the shifters.
     
  5. jeffj

    jeffj Bloated Mountain B'hiker

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    7 and 8 speed cassettes use 5.0mm spacing between the gears.

    9 speed cassettes are at 4.34mm spacing between gears.

    8 speed cassettes and 9 speed cassettes are the same overall width.

    Your 9 speed shifter indexes one more time across the same distance regardless of the ratio.

    If you use 9 speed shifters with an 8 speed cassette or vice versa, you won't shift well through all of the gears although you may get some of them to work OK.

    I don't wonder why SRAM and Shimano are not compatible. I know the difference. I have both SRAM and Shimano systems. I have 8 speed bikes and I have 9 speed bikes. I have over a dozen bikes in my garage right now.

    http://www.sram.com/en/service/sram/faq.php?faqID=02e74f10e0327ad868d138f2b4fdd6f0
     
  6. b3rnard

    b3rnard Member

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    That's what the high-low adjustment/limit screws are for.

    You can't use it vice versa.

    You got over a dozen bikes to play with, try it out, it works.
     
  7. jeffj

    jeffj Bloated Mountain B'hiker

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    No. The high/low adjustment screws are to keep the chain from going over the top of the largest cog into the spokes and off the smallest cog into the frame dropouts.

    8 speed and 9 speed shifters move the derailleur the same distance overall.

    The 9 speed shifters (using 8 clicks plus the position they start from) move the rear derailleur 4.34mm each time they shift.

    The 8 speed shifters (using 7 clicks plus the position they start from) move the rear derailleur 5.0mm each time they shift.
    ======
    From Park Tool website (maybe you'll believe them):

    "The limit screws do not control the derailleur on the sprockets between the two extremes. These are set using the barrel adjuster and tension on the inner wire. The limit screws are usually marked "H" and "L". The "H" controls the outer most limit of the derailleur, and the "L" controls the inner most limit."
     
  8. nomadFF

    nomadFF Member

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    I read this thread with some confusion. But I figured it out. "Works" in this thread does not mean works like new, or how it is supposed to, but works. Like " Hey , I just put my handlebars on backwards and it works!". So yea, its kind of like that.
     
  9. b3rnard

    b3rnard Member

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    I don't need to waste time on the park tool site. My input is based on real world experience.

    I get what they are saying.

    If you have an 8 speed cassette, 9 speed shifter, and you set the limit screw so your "derailleur" can't get past the 8th cog - it doesn't matter how much you force your 9th index, the derailleur is not going anywhere with the limit screw set :lol:. You will end up breaking the shift lever or snap the cable but the derailleur still not going to get past the biggest cog.

    :wave:
     
  10. nomadFF

    nomadFF Member

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    I dont think it would be a waste of time at all.

     
  11. jeffj

    jeffj Bloated Mountain B'hiker

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    So why are you even mentioning limit screws?:wave:
     
  12. b3rnard

    b3rnard Member

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    You so smart.

    You figured it out, it is exactly like that :lol:
     
  13. osmarandsara

    osmarandsara Active Member

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    it works


    Hey I tried using a Shimano 9-speed shifter with a Shimano 8-speed cassette as an "emergency" the other day. Yeah, it "works":lol::lol::lol:

    (but seriously, there was nothing I was able to do with H/L adjustments or the cable adjustments to make it stop from ghost-shifting, or even just shifting correctly for that matter)

    During the ride, during one of my frequent "derailleur adjustment" stops, my friend Andy (who was a bike mechanic) eye-balled my set-up, gave me this "WTF" look and then just shook his head dissprovingly.....

    Of course I lied and told him, "I just did this as an emergency so I could ride today, I knew it would do that "
     
  14. AKAlan

    AKAlan Member

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    I could see it working for cruising around but I think shifting under load could be bad. Just upgrade the cassette at the same time, if you shop around they're not that expensive.
     
  15. coolbreeze

    coolbreeze Looking for the gun show?

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    I'm with jeffj on this one. I had a 9 speed SRAM twister with an 8 speed cassette. It may work, but will jump in an out of certain gears, which can be annoying. You may not be able to get it into certain gears as well. Adjust all you want, but you'll definitely have problems shifting. I have a 9 speed SRAM cassette 34T if you want. $15 bucks.
     
  16. 2wheel_lee

    2wheel_lee Active Member

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    This thread is proof of why you should be cautious of what you read on the internet.:rolleyes:

    These adapters from Jtek (Shiftmate model 2) supposedly allow you to use a Shimano 9 speed shifter with an 8 speed cassette. I've never used one, though. But for $35, you're better off buying a cassette.
    http://jtekengineering.com/shiftmate.htm
     
  17. DirtymikeTDB

    DirtymikeTDB Guest

    Ok check it.

    B3nard, I guess you dont care about shift quality, or longevity of your drivetrain.

    The spacing between the gears on an eight speed cassette and a nine speed cassette are different, even with using a 1 to 1 shifter, it is not working properly, the nine speed shifter does NOT move the derailer the same amount as the eight speed, you CANNOT argue that, it is fact. YOur real world experience scares me.Please dont advisee people to do things that are incorrect.

    seven and eight are interchangable, nine speed is not. If you insist on using a nine speed shifter on an eight speed cassette, pick your favorite gear, and adjust the derailer to that gear because its the ONLY one that will work correctly.






    This is a great time to close this misimformative thread. Sorry OP, you need both
     
  18. mtbdad

    mtbdad Member

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    Now I understand

    Thanks to all for the info. I lost the ebay auction on the x.9 shifters so I don't have to worry about a partial upgrade now. I try to find a deal on shifters/ rear cassette package maybe ?

    My wifes old bike had grip shift so I may go gripshift or trigger.
     
  19. coolbreeze

    coolbreeze Looking for the gun show?

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    ebay can get kinda pricey on bike parts. You definitely will find a better deal here on the forum. You might want to check out the upcoming Serfas swapmeet May 9.
     
  20. mtnbikerfred

    mtnbikerfred Super Moderator

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    I read on the interweb that it's ok as long as you use a 10 speed chain
    8-[:lol:
     

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