Bicycle Mechanics - Converting from 7 to 8 speeds.

I've got a 2000 or so Hardrock I want to convert to an 8 speed this weekend. The mechanic at the now closed LBS told me I could use up to a 9 speed cassette on the frame when showing me how to do wheel bearing service a few months ago after noticing 2 spacers on the axle. I've got a new Shimano 8 speed cassette (the current cassette is a Shimano 7 speed), 8 speed Shimano shifters and a 9 speed RD I've been using with the 7 speed cassette for years, as well as a new 7/8 speed Shimano chain. I'm assuming I've got the parts I need and then some; will I need to use both spacers to maintain the correct spacing after switching to the 8 speed cassette? Or do I remove only 1? Remove both?

The big difference is the cassette freehub body. The 7 speed freehub body is a bit shorter than the 8-9-10 speed freehub body. You *can* swap the freehub bodies easily enough however once you do so, you will more than likely need to respace and redish the rear wheel so that it centers properly. I am not sure but you should measure your dropouts. They should be 135mm but if they are 130mm, you still should be okay. Is it steel or aluminum? If its steel, no big deal. If its aluminum with 130mm dropouts then that is just something else to consider.

Don't use a 9-10 speed cassette, they have different cog spacing than 6-7-8 spacing. 6-7-8 spacing is so close that you can use the same chains, shifters, etc. if you move to 9 speed, you will need to replace the chain with a 9 speed chain, replace the cassette and possibly the front derailleur but I'm not sure on that. You can not use say 8 speed shifters with a 9 speed cassette or a 9 speed shifter with an 8 speed cassette, the spacing is off and shifting won't work properly.

The big thing you are missing is an 8-9-10 speed freehub body at this point. Or do you have a 8-9-10 speed freehub body on there with a 7 speed cassette and spacer present?

Most likely, you have a freewheel rather than a cassette. If so, you would need the appropriate freewheel tool to remove the old one. any LBS should do this for a very low cost or perhaps free if you are buying something there. Spacing may be fine so laong as you end up with the 135mm that it is now from locknut to locknut.

Most likely, you have a freewheel rather than a cassette. If so, you would need the appropriate freewheel tool to remove the old one. any LBS should do this for a very low cost or perhaps free if you are buying something there. Spacing may be fine so laong as you end up with the 135mm that it is now from locknut to locknut.

Freewheel on an early 2000s era hardrock? You really think that it came with one?

I almost bought a mid 90's hardrock a few months ago and it had a freehub/cassette on it. It seems to me that almost all decent LBS based mountain bikes from the early '90s and up have freehubs and cassettes. My Fuji, Specialized, Giant all have freehubs on them and they are all from the early '90s. As far as I know, mainly cheaper box store MTBs had freewheels.

I have seen them both ways. My daughter's 2000 era Giant has a 7 speed freewheel on it as did many others from the era that I have worked on.

The frame is steel, and when the mechanic looked at it he said it had been spread to accept the wider cassette. I think I have a cassette on there, the old one and the new one in a Shimano box both look the same with similar looking internal splines. I ordered the new cassette from a different local shop who said it should work with the parts I have now, and the axle looks like the one on the right in this picture (http://sheldonbrown.com/freewheels.html). 251715

I have seen them both ways. My daughter's 2000 era Giant has a 7 speed freewheel on it as did many others from the era that I have worked on.

Interesting. The only time I have seen freewheels on later '90s and 2000s bikes were either cheaper box store bikes or the road/hybrid versions. I looked at a later '90s era Giant Option that had a freewheel. But i always have seen the MTBs with freehubs. Learn something new every day.


The frame is steel, and when the mechanic looked at it he said it had been spread to accept the wider cassette. I think I have a cassette on there, the old one and the new one in a Shimano box both look the same with similar looking internal splines. I ordered the new cassette from a different local shop who said it should work with the parts I have now, and the axle looks like the one on the right in this picture (http://sheldonbrown.com/freewheels.html). 251715

Its not the cassette that matters, its the freehub. You need to make sure your current wheel has the larger 8-9-10 speed freehub on it to take the 8 speed freehub. That is what I was referring to in my other post. If you have a 7 speed freehub, its still doable, just a bit more work involved and you will need to get another freehub body.

[QUOTE=bobotech;14256695

Its not the cassette that matters, its the freehub. You need to make sure your current wheel has the larger 8-9-10 speed freehub on it to take the 8 speed freehub. That is what I was referring to in my other post. If you have a 7 speed freehub, its still doable, just a bit more work involved and you will need to get another freehub body.[/QUOTE]
Would a 7 speed freehub need a pair of spacers to fit the 7 speed cassette? The mechanic said something about the spacers being added to make the 7 speed cassette work, but I don't remember exactly what he said. Will the new cassette work on the old freehub if it fits regardless of the number of spacers used? Even if it fits without any spacers?

why? is there a gear ratio you miss? what is it?
sort out the ratio on its own.
'speeds' is just a cog count, unless its an internal gear hub..

why? is there a gear ratio you miss? what is it?
sort out the ratio on its own.
'speeds' is just a cog count, unless its an internal gear hub..

I want to make the gap between 4 and 5 smaller, and that's 3 teeth on current cassette. When I mentioned that at the shop I bought the new cassette from they said "you must ride a lot, most people don't notice that", and " I know just what you mean".

Would a 7 speed freehub need a pair of spacers to fit the 7 speed cassette? The mechanic said something about the spacers being added to make the 7 speed cassette work, but I don't remember exactly what he said. Will the new cassette work on the old freehub if it fits regardless of the number of spacers used? Even if it fits without any spacers?
That is kind of the big question. yes, you can use a spacer on a 7 speed cassette to use it on a 8-9-10 speed freehub.

Take the wheel off, and remove the cassette and lets look at what we have. At least take the wheel off and take some close up shots of the cassette area to see if we see spacers.

maybe a straight block , will do.. 13-19 [7 of them,inclusive]
adjust where that range lies with a chainring change.
Glacially flattened Chicago .. 1 chain ring should do..

no motor, Are you referring to spacers on the axle or spacers on the freehub. Big difference. If you have spacers on the freehub (I'm not referring to the spacers between the gears of the cassette), then you have a 7 speed cassette that was mounted on a 8/9 speed freehub and you are really in luck. All you would have to do is replace the 7 speed cassette and additional spacers with the 8 speed cassette and your other parts and you're good to go. BUT If you have the stock rear wheel (silver Alex rim/Shimano hub) for a 2000 Hardrock, it came with a 7 speed cassette/freehub and the 'spacers' the mechanic was referring to are the spacers on the axle that center the wheel. To upgrade that wheel to 8 speed you'll have to replace the 7speed freehub with an 8/9/10 Shimano freehub (use a 10mm hex for that) and you will have to try different spacers along with re-dishing the wheel to center it (been there/done that for the same bike).
If you do have to make changes to your wheel, now would be a good time to think about replacing that wheel if you were inclined to do so.

That is kind of the big question. yes, you can use a spacer on a 7 speed cassette to use it on a 8-9-10 speed freehub.

Take the wheel off, and remove the cassette and lets look at what we have. At least take the wheel off and take some close up shots of the cassette area to see if we see spacers.

I can take some pictures tomorrow and post them on Thursday. I took the cassette off a couple of weeks ago when I replaced a spoke, and there were 2 of them on the drivespline that were separate from the cassette.


no motor, Are you referring to spacers on the axle or spacers on the freehub. Big difference. If you have spacers on the freehub (I'm not referring to the spacers between the gears of the cassette), then you have a 7 speed cassette that was mounted on a 8/9 speed freehub and you are really in luck. All you would have to do is replace the 7 speed cassette and additional spacers with the 8 speed cassette and your other parts and you're good to go. BUT If you have the stock rear wheel (silver Alex rim/Shimano hub) for a 2000 Hardrock, it came with a 7 speed cassette/freehub and the 'spacers' the mechanic was referring to are the spacers on the axle that center the wheel. To upgrade that wheel to 8 speed you'll have to replace the 7speed freehub with an 8/9/10 Shimano freehub (use a 10mm hex for that) and you will have to try different spacers along with re-dishing the wheel to center it (been there/done that for the same bike).
If you do have to make changes to your wheel, now would be a good time to think about replacing that wheel if you were inclined to do so.

The spacers are on the freehub, and go between the lowest/largest gear on the cassette and the outer flange of the hub. The spacers aren't a part of the cassette. I had to remove the cassette from the wheel to get to them, they're not between the cassette lockring and the dropout if that describes the location any better. There are 2 of them, and they are different thicknesses. I replaced the rear wheel about 5 years ago after bending the wheel that came with the bike. There was enough room to get the chain between the spokes and the cassette when I was adjusting the RD too.

"All you would have to do is replace the 7 speed cassette and additional spacers with the 8 speed cassette and your other parts and you're good to go." I think this is what I need to do - would I use any of the current spacers with the 8 speed cassette if I did have a 8/9/10 Shimano freehub on the bike now? I'm guessing the spacers are designed to fill in the extra space when using a thinner cassette on the wider freehub, and am unsure of the widths of the 7, 8, 9 and 10 speed cassettes.

From the sound of it, you won't need to use the spacers when you put on the 8-speed cassette. Just out of curiosity, are you changing from the 12-28 7-speed cassette to the 11-28 8-speed? :)

- Scott

From the sound of it, you won't need to use the spacers when you put on the 8-speed cassette. Just out of curiosity, are you changing from the 12-28 7-speed cassette to the 11-28 8-speed? :)

- Scott
No, both are 11-18.

From the sound of it, you won't need to use the spacers when you put on the 8-speed cassette.
That was what happened, swapping the cassettes and readjusting the RD was pretty easy and everything lined up like it should. Thanks for all the help.

That was what happened, swapping the cassettes and readjusting the RD was pretty easy and everything lined up like it should. Thanks for all the help.

Sweet! Gotta love a happy ending.