Bob Ross

Walters-Storyk Design???

SoSmellyAir

With respect to Trek, WSD is Women Specific Design.

Lombard

You were doing great until here. It doesn't matter if the rear derailleur is an 8, 9 or 10 speed as the derailleur only does what the shifter tells it to. Yes, the number of speeds of the shifter and cassette have to match, but as far as the derailleur, the only requirement is..........

Which on Shimano 8, 9 and 10 speed road groups are the same. 11-speed is different.

Correct.

No. The chain rings do not care how many rear speeds you have. The only thing the number of chain rings has to match is the number of speeds of the FRONT shifter.

Lombard

If you have a 9 speed shifter, you will need a 9-speed cassette.

However, your existing wheel is fine with either an 8 or 9 speed cassette as the freehub is designed to work with 8, 9 and 10 speed cassettes.

Also, you do not need to change your rear derailleur if you change your cassette. Keep in mind that the total width of an 8 and 9 speed cassette is the same which is why the spacing between individual gears is different. But your derailleur doesn't care about spacing between individual gears, your shifter determines that. The derailleur is only "along for the ride" so to say.

It sounds like a 9-speed cassette is the only part you may need. NOTHING ELSE.

SoSmellyAir

Lombard I now get what you meant about the RD itself does not matter as long as the number of speeds matches between the shifter and the cassette.

But I think you misunderstood me when I said the chain determines which chain rings can be used. For example, I run 10 speed Shimano chain rings on an otherwise 11 speed Shimano drivetrain.

SoSmellyAir

I don't think so. VegasJen said (in post #1) that "[t]he cassette on it now is a 9 -speed, but I think it came with an 8-speed originally (not sure)." She then described shifting issues, which may be due to using an 8-speed shifter (corresponding to the original 8-speed cassette) with the current 9-speed cassette. She needs to first determine whether her shifter is 8-speed or 9-speed. If it does turn out to be an 8-speed shifter, then she needs to buy either (i) an 8-speed cassette to go with that, or (ii) a 9-speed shifter to go with the current 9 speed cassette. Either way she does not need another 9-speed cassette.

Koyote

Yup, Unless it's electronic, a rear derailleur is a pretty 'dumb' device. For example, I'm running a D/A ten speed RD on my older nine speed bike, and it works beautifully.

VegasJen

Thanks. I just received a replacement for the broken wheel. It has an eight speed cassette, which I am 95% certain was the original configuration. I will mount the wheel tomorrow and see how it goes. I will report my results.

Lombard

Oooops! Massive brain fart on my part!! You are correct here!!!

I still don't understand why you say "the chain determines which chain rings can be used". This implies you are saying the number of speeds rating of the chain ring must match the chain. Am I missing something?

Precisely!

Koyote

Several people in this thread explained how you can determine which cassette to use… And you still haven’t checked it?

cxwrench

You could have just counted the cogs on the old wheel and/or counted the clicks in the shifter and saved everyone a bunch of time and you'd know for sure...but no. Why not?

VegasJen

Probably because the wheel that was on the bike when I bought it wasn't original?

SoSmellyAir

All I am saying is that (A) the cassette determines which chain to use, and (B) in turn, the chain determines which chain rings can be used. (A) generally has a 1:1 correlation, i.e., an 8-speed cassette requires an 8-speed chain, a 9-speed cassette requires a 9-speed chain, etc. Whereas, (B) may be broader. For example, I use 10-speed chain rings on an otherwise 11-speed drivetrain.

Technical FAQ: 10- and 11-speed drivetrain component compatibility - VeloNews.com

SoSmellyAir

The only logical conclusion here is that the OP (a) cannot, (b) does not want to, or (c) does not even know it is possible to remove the cassette from the wheel.

genejockey 

Perhaps referring to possible problems running things like 8 speed rings with 10 speed. When I updated my Ritchey from 8 speeds to 10 by swapping the 7400 series RD and STIs for 7800 and adding a 10 speed chain, I initially kept the 8 speed chainrings, and it MOSTLY worked fine. But twice, my chain fell into No Man's Land between the rings. It didn't jam there, it just sat uselessly in the gap as I spun the cranks. I got the 9 speed small ring, which reduces the space between the rings and no problem. I suspect, but I'm not certain, that a difference of one speed between the generation of the rings and the drivetrain (and thus the chain) isn't a problem, but the greater the difference the more likely it is to occasionally fail.

SoSmellyAir

Yes, from what I can gather, these issues arise because (a) chain width decreases as the number of "speeds" increase, such that (b) chain ring width must also decrease correspondingly. To maintain good front shifting, the spacing between the chain rings is also decreased, except for the respective specifications between 10-speed and 11-speed road drivetrains. Thus, 10-speed rings can be used on an otherwise 11-speed drivetrain without issues.

genejockey 

I don't think the thickness is the issue as much as the spacing. The 8 speed big ring on the Ritchey works fine with the 10 speed chain.

Lombard

This sounds about right.

Koyote

And is apparently incapable of counting to eight or nine, and hence will not simply click the shifter a few times to determine the number of speeds.

Honestly, I wonder why some posters even bother asking for advice when they just ignore it.

cxwrench

The inner wide of chains (all of them...5-8=2.38mm, 9-12=2.18mm) is basically the same. The outer width is what changes.That's why it's chainring spacing that changes.

I don't have any idea why the OP doesn't want to follow the dead simple advice posted multiple time either.