Adding Extra Gear to Cassette
 

I know this is one of those questions that generates a lot of hate so I will keep it succinct;

Basically I have a pretty much unused 8 Speed 13-28t cassette which came with a bike (Alan team cyclocross) I recently purchased. I am however planning on running this bike as a 9 speed as I already have the Dura-Ace Bar ends in this speed.

In the long run I'm probably going to want to run a 11>32, but for now I'd like to muck about on this as I've never used a close ratio cassette in an off road setting before. I'm bound to have a 11t cog kicking about somewhere and was wondering if you guys think I'll have any issues slapping this on the end? I doubt I will but forewarned and all that.

Cheers guys!

The spacing between cogs is different, so your shifters won't index.
That's in addition to not having any room to put on an extra cog.

why don't you try putting it on the end and let us know? shouldn't take long...

Spacing on 8 speed vs 9 speed cogs is quite different. Very strong chance that unless you use friction shifting, a 9 speed index shifter won't properly shift a 8 speed hub with an extra cog.

Also how would you add the extra cog? the 8-9-10 speed cassettes are the same physical depth, the only real difference is the thickness in the gears and the thinner spacing.

If you put another cog on an 8 speed cassette, it would be too big for the locking ring to tighten down on the hub.

Not quite so. The vast majority of modern freehubs have spacing for 9 speed cassette's and if you wish to run 8, you use a spacer in it's place. This is the case with the hub I am going to be using.

As for the spacing, I'll wait and see!

Edit: As for trying it my self, I could indeed mount it up and give it a go. Or I could ask a vast pool of seasoned experts online for no cost other than an hour of my time to wait on a reply. Thus I give you the beauty of the forum based community.

wut?

freehubs for 8, 9 and 10 cassettes all have spacing for 8, 9 and 10 speed cassettes because they're the same width. Where would this extra spacer go?

That would be the case if you were using a 9 speed shifter with a 9 speed cassette that had one cog removed. Then you would use the limit screws on the rear derailleur to lock out the top or bottom gear on the shifter.

But you would not be able to reliably use a dedicated 8 speed shifter with a 9 speed cassette that had one cog removed, the cable pull on the 8 speed shifter is different than the 9 speed shifters.

Almost ALL modern freehubs since the early 8 speed days are the same size due to the overall physical size of the 8-9-10 speed cassettes being the same with the only differences are the smaller spacing and thinner gears on the higher speed cassettes.

But comparing a real 8 speed cassette to a 9 speed cassette minus 1 gear is completely different and would use a different shifters and setups. Apples and oranges.

The why the hell you asking us?

I believe he is referring to removing a cog from a 9 speed cassette for some reason, not using a real 8 speed cassette.

It is replacing the chain and cassette, not adding a gear to the existing set,

got the lever , for 9 speed already,? good..now buy the rest of the system.
substituting the last cog, say a 12 for the 13, may work
with out adding to the cog count.

I don't think the cogs are thinner, just the spacers.


I think he has a 9-speed hub that didn't come with the bike, and he wants to put one more cogwheel on the 8-speed cassette that did come with the bike and put it on his 9-speed hub. He's confused because he's thinking a 9-speed cassette minus one cogwheel plus a spacer on the end is the same as an 8-speed cassette.

Right, that's my question answered. I was under the impression that modern cassettes, regardless of speed we're of all the same spacing and simply used spacers to compensate.
The whole point of wanting to chuck a bodged 9 speed is that I have the rest of the drivetrain in it's entirety minus a cassette and fancied playing around with a close ratio cassette. Alas I'll have to throw an extra £20 to get exactly what I need (:

I did double check and no spacers on the hub I missed, so defo a 'native' 8 speed cassette.

Cheers all and sorry for confusion.

Nope, 7 and 8 are spaced the same , but frame has to be wider to fit.
9+ are cramming in more cogs without taking up more width.
Just taking up more money. chains go from $15 [5,6,7,8.] to $45 for 10

Now that you say that, I think you are right. I have seen others mention that you can use front double and triple cranksets designed for 9 and 10 speed bikes with 6-7-8 speed chains.

Right, 7 and 8 speed have the same spacing BETWEEN the cogs, but 8, 9, and 10 use a wider freehub body and have unique spacings between the cogs (and all have unique chain widths). if you have the right shifters and chain for the cog spacing, and don't want to swap an 8 speed+ width freehub body onto old wheels, you can go one speed down on a 7 speed freehub width. That is make an 8 speed out of a 9 speed cassette minus a cog and use a 9 speed shifter and chain.

EDIT: for the record the cogs ARE thinner, but the pin to pin distance on the chain is the same, so a wider chain will work if you don't have to shift it, or it's in the front where the size difference is so dramatic.

SHELDON LINK

Except that the first position cog has a built-in spacer. I had to grind down an 8-speed 13t cog built-in spacer to make it work on a 9-speed cassette.

I think everyone covered it and you've got it figured out now, BUT just to be clear the above information is incorrect. 8/9/10 speed Shimano cassettes all use the same freehub body, and actually the only cassette to use a spacer is the 10 speed because it is just a bit narrow. You cannot add another cog onto an 8S cassette. You can, however, run your 9S DA bar-end shifters in friction mode if you really want to use up that cassette you have.

:wtf:? Not sure what you're referring to here. It's really a matter of correct vs incorrect on well established facts. Not like those chain lube threads...

I'm not sure if I'm misunderstanding you but I think you have a slight error.

7S and 8S spacing is just a tiny bit different. 7S Shimano is 5mm and 8S Shimano is 4.8mm. So you can sometimes go back and forth with the 7/8 shifters/cassettes, but it does not always play well. It can be tricky to get it setup just right if you mismatch.

Hmm, I've never had an issue. I knew they were different, but in the name of minimal confusion, I left that detail out. In fact, those suntour XC pro 7/8 speed thumbies used to come OEM on kona MTBs in the 90s. Never had an issue there either.

I tried to use an allegedly "9 and 10 speed compatible" crankset with a 9 speed chain and found that I didn't have any usable overlapping gears due to the chain rubbing on the big ring until I shimmed the small ring inboard to 9 speed spacing.

More speeds means narrower cogs, narrower chains, and tighter spacing in the front rings.

5-6 speed chains are 7.4-7.6mm wide
8 speed chains are 7.1-7.4mm wide
9 speed chains are 6.6 - 6.9mm wide
10 speed chains of current production are 5.9mm wide (Campagnolo started at 6.1mm)
11 speed chains are 5.5mm wide

Front deraileur cages are narrower too as speeds go up.

It will work I could put 2 gears there with 9 cog spacing or 3 gears with 10 cog spacing. http://www.flickr.com/photos/6337399...in/photostream We are Scottish the best engineers in world.

I don't believe for a moment that photo was taken in Scotland, much too blue a sky ;)

Interesting stuff though.

Close, but no cigar.

A 9-speed cassette puts 9 cogs in the same amount of space that an 8-speed cassette puts 8 cogs. Obviously they have to be spaced more closely. Both the cogs and the spacers between the cogs are different.

To turn an 8-speed wheel into a 9-speed, just install a new 9-speed cassette. It'll even come with it's own new lockring.

There are many mis-understandings, here's some clarifications on Shimano freehub-spacing:

Notice that not a single cog or spacer will interchange between the different speeds. The cogs are all different thickness as is the spacers and c-t-c spacing between the cog-centres. The difference between 7 & 8-spd is the smallest and sometimes you can mess with cable-tension to get most shifts to work OK if you mix & match 7 & 8-spd parts. If you adjust RD so that it shifts well in the middle of the cluster, you only have the end-gears that may mis-behave.

As to adding a cog to 8-spd to get 9-spd, there are many ways to do it. The only way to re-use the existing cluster with 100% compatibility is to grind down the spacers to 2.54mm so that you have 4.34mm c-t-c spacing (including the top cog with built-in spacer). Note that you can't just replace the 8-spd spacers with 9-spd ones as the cogs themselves are thinner on the 9-spd cluster.

The 11t cog represents a unique configuration. It requires a Hyperglide-C freehub body where the splines do not go to the very end:
http://sheldonbrown.com/images/2k7-bodies.gif
http://sheldonbrown.com/images/2k7-bodies.gifhttp://i42.photobucket.com/albums/e3...himano11tl.jpg.
that's because the 11t cog has a solid outer-surface for the necessary strength and this cog won't slip down all the way on a regular freehub body. You will also need a 11t-specific lockring, the regular lockring will cause the chain to ride up on the lockring instead of falling down into the sprocket teeth.

Then the issue of RD comes in. If the one on the Alan is an 8-spd Dura-Ace, it will not work with 9-spd Dura-Ace shifters. Shimano got rid of the unique Dura-Ace cable-pull distances when they went to 9-spd and made Dura-Ace the same as the rest of the line. You may need to get 9-spd compatible RD.