9spd shifters with 8spd cassette

[Justin]

Hi

 

 

 

Is it possible to use 9spd shifters with a 8 speed cassette?

 

 

 

Maybe by setting the High limit on the derailleur and thereby forcing the shifter not to be able to go past 8?

 

 

 

Any idea?

[parabola]

 

No it wont work. The total amount of travel the derailer moves is the same for 8sp and 9s, the only difference is that the chain is thinner and the sprockets are more closely spaced. So its not a case of the 9sp shifter has more 'travel' but that each incremental movement of the shifter is smaller. To make it more clear, each shift of an 8sp shifter moves further than what is required for the 9sp standard.

parabola2009-11-24 04:45:10

[TNT1]

Yes. It will work.

[techguy]

Wouldn't it be easier to buy a 9sp chain and cassette? You can make it (sort of) work, a lot of carefull adjustment and patience will help...

[parabola]

 

 

 

Look we are talking about a fractional difference here, according to google, 8 speed cog spacing is 4.8mm and 9 speed is 4.34mm. So it may work for a bit, but you will be exerting more load on the rear mech and chain, so you can expect more shifting problems than usual.

You might just be better off sourcing an 8sp shifter. I'm selling a set of 8sp v-brake STI's but not sure what you need.

https://www.bikehub.co.za/forum_posts.asp?TID=68310&KW=mtb+parts

 

@techguy you would also need a 9sp derailer to complete the upgrade.

 

 

parabola2009-11-24 05:04:41

[Justin]

 

@techguy you would also need a 9sp derailer to complete the upgrade.

 

 

 

 

No, you don't get 9 or 8 speed derailleurs. You have to change the travel of the dr. I am currently using a XTR rapid rise on a 8spd cassette...

[parabola]

 

 

@techguy you would also need a 9sp derailer to complete the upgrade.

 

 

 

 

No' date=' you don't get 9 or 8 speed derailleurs. You have to change the travel of the dr. I am currently using a XTR rapid rise on a 8spd cassette...[/quote']

 

Quite right. My mistake.

 

[mtbN00b]

so you saying that you can use a 9spd shifter on 8spd cassette perfectly?

 

[Fleming]

I have never tried this but highly doubt it is is possible.

 

As someone mentioned the spacing between the sprockets is different between 8 and 9 speed cassettes. I dont know exactly what the difference is but using the dimensions parabola gave above it works out to 0.46mm. You might think this is insignificant but it is. This is only the difference between 2 sprockets but it increases each time you move further up the cassette. If you use a 8 speed cassette with a 9 speed shifter and set it up so that the derailleur lines up with the smaller sprocket by the time you have shifted to the 8th sprocket you will be 0.46 x 8 = 3.68mm out of alignment. I think we can all agree that this is alot.

 

Perhaps you can get it to work with a some very fine tuning but I don't think it will stay working for very long. Rather get a 9 speed cassette and chain to go with the 9 speed shifter of stay with 8 speeds.

 

 

 

[Justin]

Well, that's what I am asking. I have 8spd shifters and cassette, but want to slowly start upgrading...starting with the shifters first.

 

However, I think it should work fine...given the right tuning.

[Justin]

by the time you have shifted to the 8th sprocket you will be 0.46 x 8 = 3.68mm out of alignment. I think we can all agree that this is alot.

 

 

 

 

Surely setting the amount the derailleur shifts (barrel at cable end) you can get past this. Just ensure that the cable derailleur moves a bit less. Huh?

[TNT1]

 

so you saying that you can use a 9spd shifter on 8spd cassette perfectly?

 

 

Yes. Cause I have run that setup.

 

[Scooterza]

I once was sold a tandem by Frans at Tour de Frans cycles that had been fitted with a 9 speed STI shifter set but had an 8 speed cassette. That thing gave ENDLESS hassles and when TDF cycles EVENTUALLY admitted that they had sold me a dud, they took it back on condition I buy a new bike! (Can you guess how often I have been back to TDF cycles?)

 

 

 

The point is, I know how to set up a bike's gears and no amount of tinkering would get it to work. If it worked in some of the gears, others would be out. Endless adjustments back and forth but no reliable solution. I wouldn't recommend it.

[Flowta]

 

by the time you have shifted to the 8th sprocket you will be 0.46 x 8 = 3.68mm out of alignment. I think we can all agree that this is alot.

 

 

 

 

Surely setting the amount the derailleur shifts (barrel at cable end) you can get past this. Just ensure that the cable derailleur moves a bit less. Huh?

 

The barrel adjustment doesn't change how much it shifts, just the start and end of it.

 

The shifter will pull the same amount of cable everytime causing the derailleur to move the same everytime.

 

[Ox_Wagon]

Here is a nice artical

 

http://www.ctc.org.uk/DesktopDefault.aspx?TabID=3946

 

Also check shelden brown

 

Ox_Wagon2009-11-25 00:08:56

[Justin]

No. When shifting gears, and the first 2 go fine, but after that it starts grinding and jumping, change the barrel.

 

This doesn't mean that the 3rd and 4th will work fine but the 1st and 2nd not.

 

 

 

It means that the derailleur will shift a bit more, ensuring that it doesn't go out my 1 mm on each shift, resulting in a 7mm difference at gear 8. (all random numbers)

 

 

 

The barrel does change the amount the derailleur shifts.