I'm looking into replacing shifters on my MTB. Currently I have 8-speed Shimano Alivio shifters - will 9-speed Deore or SLX shifters work? I do not care if one of the shifter's position will be unreachable.

Later I may replace the cassette to 9 speed to, but I do not want to do this right now.

  • 1
    I'm adding this is a comment because I'm not sure, hopefully someone else can confirm. But AFAIK 8/9 speed MTB shifters are designed for different width chains, so their indexing positions are different. In short you'll never be able to calibrate it. But 8sp derailleurs are still widely available, can't you just buy one of those?
    – cmannett85
    Feb 9 '12 at 7:25
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    @cmannett85 It's not the chain width that's a problem, it's that the distance between the cogs needs to match up to the amount of cable pulled by the derailleur. But you are correct in that the shifter and the cassette are incompatible.
    – jimchristie
    Mar 27 '15 at 12:33

Unfortunately you cannot do that. The COGSET and the SHIFTER must have the same "distance", or more correctly, the same lateral distance (on the pulley) for each lenght of cable pulled (on the shifter).

When you go from 7 to 8 speed, the distance between cogs is the same (because the freehub shell is longer), so you could use a 7 shifter with an 8 cogset and one gear would be unreachable;

But when you go from 8 to 9 speed on the shifter, the expected distance between cogs change (because the freehub shell for 8, 9 and 10 speed is the same). Then you need a 9 speed cogset too, so that EACH shift will correspond to the CORRECT DISTANCE of lateral movement in the derailer.

If you move from 9 to 10, the same problem happens. That's a perverse kind of programmed obsolescence, in my opinion, since even cranksets end up being incompatible due to the chain being narrower and narrower... (look for the Sheldon Brown "Nanodrive" system).

So the bottomline is: if you want to replace shifters, you'll have to replace the cogset, and probably the chain and cranks. I would not advise you to do so only for the sake of shifter change. Consider doing it only as a last resouce.

(I for one never changed to the 9+ speeds framework. I have 5 bikes in current use, all of them with the "7/8 speed framework", and I can easily find spare parts like cogs. My 7 speed shifter (a very old Alivio) still works fine, and it seems to me it is very rare for the shifter to have a poor working only because it got old).

  • 1
    Thanks for your answer. For completeness sake - an article here: ctc.org.uk/DesktopDefault.aspx?TabID=3946#Shiftratio - suggests that maximum error in an ideally adjusted 9/8sp combo would be about 0.6 mm which is less than the derailleur's "wobble" or margin of error, so in theory such a combination could work after all. But it definitely would require more accurate adjusting.
    – Sergey
    Feb 9 '12 at 20:37
  • @Sergey Just some points: the article suggests you can use a 9 speed derailer with an 8 gear shifter/cogset or vice-versa, not mix shifters and cogsets of different types; The error you mentioned would exist for a correctly matched group, "within" each gear, not across gears; Since total width of 8 and 9 cogsets is the same, measured from first to last, mixing 9spd shifter and 8spd cog would be like having a shirt with 8 buttons and 9 button houses. Unfortunately, it won't work :o( Feb 9 '12 at 23:06
  • Sorry, I linked to the wrong chapter within the article. I was referring to the "Sprocket Pitch" chapter: "...some "incompatible" combinations actually work okay – at least when new. ... If, for example, the mech shifts 4.55mm instead of 4.35mm, the most it'll be out is only 0.6mm, and only in next-to-top or next-to-bottom. The rest of the reason is that the guide pulley can float about half a mm side to side, allowing at least that much misalignment between mech and sprocket without any nasty noises." - but they also say it would only work when the parts are new and ideally adjusted.
    – Sergey
    Feb 10 '12 at 0:03
  • @Sergey again, I'm pretty sure they're talking about shifter vs. derailer vs. cogset with SLIGHTLY different pitches/ratios, but with the same number of gears. Feb 10 '12 at 1:08
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    Ok, I re-read the article and now I see that the max error between Shimano 8sp and Shimano 9sp will be almost 1.5 mm ((4.80 - 4.35) * 3), so this setup is not going to work well even in theory. Thanks.
    – Sergey
    Feb 10 '12 at 1:42

I came across a way of allowing an 8 speed cassette to work with a 9 speed shifter. The method I used is similar, though different to hub-ub's fix. I use an 8 speed cassette (HG51) with XT 9 speed shifter and a 9 speed XT derailleur.

The gear cable (coming out from the barrel adjuster) goes around towards the wheel or the inside of the anchor bolt. You could pull the cable around the bolt and towards the back of the bike but it is not necessary (see image 1 and 2):

Image 1

Image 2

Many derailleur anchor bolts have a 'hook and tab' part or plate between the bolt and the threaded-hole:

Image 3

You may need to get one of these from an older derailleur as some of the present day ones don't have ''hooks'', only the 'tabs'. The hooks are the bent parts of the plate in the image above. They fit over the edges of the threaded hole onto the body to make their own fittings more secure on the derailleur body.

The two hooks have different size and one of them (whether the narrow or the wide depends) should 'face' towards the back of the bike, i.e. towards the barrel adjuster. The opposing hook will fit to the derailleur body. You'll see it when you're down there.

N.B. there will be 'play' in the hook's position under the anchor bolt before you tighten the bolt. this is key to fine tuning the shifting. The position of the 'edge' of the hook (touching the gear cable) when secure will affect how much the cable is shortened with each pull (movement) across the 'swing' of the derailleur, since subtle movements of the hook are what changes the cable pull.

The principle in this instance is the one of a 'cam' action. It's about cable pull and what happens at the hook if the position of the hook against the cable changes.


wanted to add a few more details to what's already posted[for clarification].

the wider hook is the main one for use with 9 speed shifters and an 8 speed cassette, not the narrow one. found this out today.

the 'narrow' hook is in play[?] to maintain an exact and secure fitting to the derailleur body[?]. am not sure if this is the case or if it's there for another reason.

the wide hook will fit exactly and won't move as the narrow hook does

the narrow hook is a problem if used. a fair bit of tweaking is necessary

you have to manouver the narrow hook's position so that when cable is pulled tight the hook doesn't move. if the wider hook is used instead, process is straight forward...tighten down the bolt make sure the gear cable is reasonably tight. tweak the shifting at the shifter adjuster and that's about it. job done.

  • Welcome to Bicycles.Stackexchange.com! Basically, as far as I could follow it, your solution sounds like a nice idea for a possible makeshift repair. However, there are are two things to improve: if possible, you could add some pictures to illustrate what you are doing since from the description it is a bit unclear. You do not have enough reputation yet to add the photos yourself, but you can edit in a link and someone else can add them in for you. Also, the internet has no space restrictions, so no need to use abbreviations (e.g. "rr/der", whatever that is). Try to be as detailed as necessary Mar 18 '15 at 9:02
  • Continued... Also, you might want to have a look at our help pages and take the tour to familiarize yourself a bit more with the philosophy of this site. Mar 18 '15 at 9:03
  • ctc.org.uk/cyclists-library/components/transmission-gears/… has a photo showing how to reroute the cable for a 9 speed cassette to work with an 8 speed shifter. My guess is that doing something more like the "New Dura-Ace convert to old style" diagram on that page could do the reverse. I agree a photo of his setup would help.
    – armb
    Mar 18 '15 at 12:41
  • (I've been using the "Campag old 9 Hubbub S7" setup for some years; it's not just for makeshift repairs. But I now have a shiny new Tiagra groupset for that bike.)
    – armb
    Mar 18 '15 at 12:44

It will totally work.

I broke my cassette on one of my bikes, then I replaced it with Shimano Megarange 18-34T. My command is 8 speed and the cassette is 7. As I adjusted the tension of the wire it still runs quite nice. Gear 7 and 8 on the command are representing 7 on the cassette. SO YES IT DOES WORK.

  • Just read this, and 7 speed and 8 speed are normally compatible anyway as they don't have any difference in spacings. So the only evidence of this working would be using 9,10,11 or 12 speeds in conjunction with an 7,8,9 etc shifter.
  • I am only sharing my experience and my opinion. If you don't like it be my guest haha Jun 29 '17 at 6:33
  • This works for you because 6/7/8 speed are all the same spacing between cogs in the cassette. But OP's question is about 8 and 9, and the inter-cog spacing is less on 9 speed than it is on 8 speed.
    – Criggie
    Feb 28 '20 at 22:11

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