Doug64

What thickness of spacer is used to put an eight speed cassette on a 9 speed free hub? Or is a spacer even needed?

Thanks

Kontact 

None needed. Same freehub.

FBinNY 

You never need to ask this question since the hub itself tells you.

Cassettes NEED TO OVERHANG the freehub by 1or 2mm. This allows the locking to tighten against and compress the cassette before bottoming against the freehub body.

Once you understand the principle, you'll always know how much spacer you need, if any.

Doug64

Thanks!

Kontact 

So buy the cassette, bring it home, try to install it, then go back out to buy the spacer?

I think I would just ask.

Schweinhund

No, take your wheel in with you and try it. get the spacer at that point if you need it.
Now you buy.

Kontact 

If you're buying from a shop, and if it is convenient to tote a wheel around.

Schweinhund

Is that not what you are saying here?
Is it a big deal to carry a wheel a couple of miles?

Kontact 

Is it a big deal to request and receive standardized information on the internet? What else is the internet really for besides distributing information?

I'm glad the OP asked the question rather than just trying to figure it out through trial and error or by lugging around bike parts to get his hands greasy trying them out on an LBS counter.

rccardr 

Hmmmm…not sure exactly how ‘standardized’ this information is.
Have had my hands on many a freehub/cassette combination and am still somewhat surprised at circumstances that require a spacer.
Not always a standard 1mm or 1.85, but purchased a bag of .5mm spacers some time ago for fine tuning.
Just slightly loose cassettes produce a jangly noise that’s hard to diagnose unless you’ve experienced the situation.
So yeah, kinda like some BB’s, sometimes you gotta install and see what’s needed.

Schweinhund

Is that the Kontact thing? OMG no greasy old stuff or hands in an LBS!!!!

Kontact 

Yes, I imagine the suggestion of doing things the easy way is very controversial.

Kontact 

Asking whether an 8 speed Shimano cassette needs as spacer on a 9 speed freehub is "dumb"? Is that answer going to ever be anything but "no"?

You are a gem, sir.

veganbikes

I am curious what was dumb about what Kontact said, they are a mechanic, and you are a_______? You generally do not need a spacer for 8-9 speed saying no you don't need one isn't dumb. Neither is trying the cassette sans spacer and getting one if needed.

Most people I have experienced don't want to remove their wheel and schlep it in. I wouldn't really want to do that unless I was having the shop do the work or there was an issue with the wheel. It is not dumb to bring the wheel it is just a hassle for some people. If you have a wheel bag that is comfortable to carry around it isn't so bad but most people don't have that and even with that I don't want to carry them or maybe I want to ride a bike to the shop that is not the bike I am working on or some other reason.

StanSeven

Moderator note: I cleaned up and edited some posts which included insults. Either post with respect or move on and ignore the thread

FBinNY 

There's nothing wrong with the request, nor with the simple answer. However......

The OP asked a specific question and got a specific answer, so far so good.

Later I on posted additional info, based on my worldview that an understanding of the involved principles is valuable and fosters a degree of self reliance. (note, I didn't quote the earlier response, nor make a comparative value judgement) I considered adding that there are many posts here on BF about cassettes not tightening down properly, and/or that despite standards, there are variations in freehub bodies and cassettes, and the OP hadn't offered specific details, But I chose not to.

So, following the old parable, You gave the man a fish, and I opted to help him learn how to fish. That should have been the end of this thread.

However, you then decided to make it fight with your snide (my characterization) response quoting of my post. I chose not to take it up, chalking it up to you being you. However, others felt you were out of line. So, please don't play the victim in a fight over nothing that you chose to start.

FWIW --- It is possible to be right without needing to prove that others are wrong.

jadmt

Bicycle MechanicsBroken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

this is what it says at the top of the forum... it should really say something like ask a question and watch the same 2 or 3 posters bicker with each other. carry on....

Soody

Yep this is true.

Kontact 

It really is not true. Their a finite number of road freehub bodies and cassettes. 7, 8/9/10, 10 Dura Ace, MTB 11 and road 11. It is very clear what spacers you need in each case.

The thing that throws people is that the DA 10 was narrower and the compatible cassettes included a spacer for use on standard 10. Sram was all the same, except without the narrow DA 10 version.

There isn't an aftermarket that is different than these combinations. Aftermarket cassettes must work on Shimano freehubs, and aftermarket freehubs must except Shimano cassettes.

This isn't like BBs that are predicated by the frame design and the crank. Freehubs of the types we're discussing just vary in width (With the exception of the DA10 which has taller splines on the body).

Soody

You've never installed a cassette that was theoretically spaced correctly, but did not actually protrude past the freehub and so was not held down tightly and so produced the jangle?
Because he has, and I have.

What's your explanation for this phenomenon that multiple people think is common?

rccardr 

Kontact, I absolutely agree with you. In theory.
In practice, I have found some surprising circumstances where a spacer is necessary.
Stuff sometimes just doesn't fit like it's supposed to.
Therefore, I always check fit after installation and sometimes find the need for a spacer.

Kontact 

That it was one of the cassettes that come with and require an extra 1mm spacer because they were compatible with those narrow DA 10 freehub bodies. On those you use the 1mm spacer plus the 1.85 spacer to work on 11 speed bodies. Or they didn't realize 11-34 eleven cassettes and larger will fit on 8/9/10 speed freehubs, so they require a 1.85 on 11 speed freehub bodies. Or they had failed to remove a previous spacer when they installed a new cassette. Seen all of these multiple times.

And no, I have not been unable to understand why I need to use whichever spacers. I was working in a pro bike shop - it was my business to know why some things did or didn't work - not just shove more spacers on and hope for the best, or play trial and error while a customer waits for their cassette to be installed.

Kontact 

You should check fit before you put the lockring on, not after. I don't know how many freehubs I've seen chewed up because people had too few or too many spacers.

But however many it takes is not a shock when you know what kind of cassette it is.