8

I want to use an 8-speed shifter with a 7-speed cassette. I saw this question, but I am unsure if this would work, since I believe the spacing is the same between a 7- and 8-speed, but the length is not.

  • If the spacing is the same, then you could, but if you shift too far you'd pull the chain right off the cassette. If it goes into the wheel, goodbye wheel (possibly). – Jack M. Apr 9 '12 at 20:17
  • Why do you want to do this? – zenbike Apr 10 '12 at 3:04
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    I have a 7 speed cassette, but the shifters are bad, and looks like there is more variety with 8 speed shifters instead of replacing the wheel or hub. – Carson Reinke Apr 10 '12 at 20:10
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You can do that, the spacing is the same.

As already pointed, you're going to have a "phantom gear" on your shifter.

If you let gear number 2 on the shifter correspond to gear number 1 in the cassette, you should take care not to press too hard on the lever when you are already in gear 2, since this should overstretch the cable or the lever.

If you let the normal order until gear 7, and have an 8th gear on the lever as an "empty" or "ghost" gear, there is no danger to overstretch anything, but the shifter cable might become too loose, to the point of the housings coming out of their stops.

Anyway, the gear spacing is the same, and there would be any necessary damage in any part, except one of the positions of the shifter not being used.

Also, this could be a good alternative to upgrade the shifter, and only some time later to upgrade the rear wheel.

At last, have in mind that these systems are not in production anymore (as far as I know).

Hope this helps

  • Sorry, could you clarify on what you mean by "not in production anymore"? Are you referring to Shimano manufacturing? – Carson Reinke Apr 10 '12 at 20:09
  • @CarsonReinke yes, I think at least for medium-to-high-end components, everything is 9 or even 10 speed, be it Shimano or SRAM... – heltonbiker Apr 10 '12 at 20:49
  • Shimano still makes 8 spd integrated brake lever shifters. Claris line. – Fred the Magic Wonder Dog Aug 28 '15 at 21:41
  • Are you sure the spacing is the same? On Sheldon's page it says that the pitch with 7-speed is 5mm, while with 8 speed is 4,8mm – Mladen Jablanović Dec 17 '17 at 15:26
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    @MladenJablanović I am not sure, that is a fact. My answer is based on what me and a lot of friends did when 8 cogs became the new standard: we just started mixing hubs, shifters and derailers of different number of cogs, and everything just seemed to work normally. But perhaps there was some difference, although not show-stopping. – heltonbiker Dec 23 '17 at 21:44
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You can't over shift if your rear derailleur is adjusted correctly (the high and low limit screws will prevent it). You will just have a phantom gear – like they say.

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It will work but as JackM. states make sure you limits are adjusted precisely.You also have to decide if you want to risk over shifting on the low gear or high side.

  • I stand corrected – mikes Apr 10 '12 at 0:39
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Assuming you have a 7 speed cassette that can be disassembled and not a 7 speed freewheel....the cog spacing (center to center) of 8 spd is 4.8mm, the cog spacing of 7 spd is 5.0mm. Replace the plastic cog spacers of the 7 spd (3.15 thick) with 8 spd spacers (3.0 thick)....readily available on line. This will yield a 4.85mm cog spacing....shifting should be oblivious to the .05mm difference. Lockring should still tighten the starter cog, otherwise get a 1mm spacer and put it under the largest cog. I have revised cassettes both ways (7 to 8 and 8 to 7) successfully.

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