This article will explain bicycle cassette compatibility i.e. what cassettes can be mixed with which rear shifters/derailleurs. For compatibility with various chains, see the chain compatibility article. Overview of compatibility and possible combinations will be given according to the number of sprockets. From the old 6 sprocket standard to the newest 12 sprocket one. There are two things to consider when combining cassettes: number of sprockets, and sprocket spacing. Both those things affect the cassette width and indexing of shifters. Table with sprocket thickness and spacing is at the end of this post.
Before you start, to avoid any misunderstanding:
please take the 5 minutes needed to read the compatibility articles use instructions.
Related article: Speeds – rear sprockets.
Indexed shifters work with clicks – each click changes one “speed”. In order to function properly, they require that derailleur movement ratio and sprocket widths are matched with shifter’s cable pull ratio. This is explained in detail in a separate article on shifters: Rear shifter compatibility.
One more thing before explaining compatibility: there are two main standards of cassette mounting. Freewheel and freehub. That is explained in the article: Freewheel vs cassette. 6 speed is always with a freewheel. 8 and more speeds is always a freehub cassette (there used to be 8 speed freewheels, but those where never widespread and are now obsolete). 7 speeds usually come as freewheel cassettes, but can also be found in a freehub cassette standard.
Most manufacturers’ cassettes (and freehub body splines) are compatible with Shimano (SRAM, Sun Race etc.), while Campagnolo cassettes use different freehub splines – that is explained on. Also, SRAM XD cassettes (and freehub body splines) differ from all the rest. All this is explained in Rear hub compatibility post. These mounting standards are important for physical mounting of the cassette on the wheel, they have nothing to do with chain and shifter/derailleur compatibility.
6 speeds
All the 6 speed sprockets are with a freewheel. As a rule of thumb, all the models of all the manufacturers can be interchanged without problems. Shimano’s standard is widely accepted, though you might come accross an “exotic” model with narrower sprockets, more narrowly packed.
Sprockets are placed at 5 to 5.5 mm spacing, with each sprocket being 1.85 to 2 mm thick (depending on the model).
7 speeds freewheel
Sprocket width and spacing is the same as for some 6 speed systems. Here, Shimano standard is widely accepted and all the manufacturers’ 7 speed freewheels are compatible with it.
Sprockets are placed at 5 mm spacing, with each sprocket being 1.85 mm thick.
7 speed freehub (cassette)
There is an obsolete Shimano Uniglide standard, and a current, Shimano Hyperglide standard. If for any reason you have a Shimano Uniglide cassette, they can be fitted onto a Hyperglide freehub, just the smallest sprocket needs to be replaced with a Hyperglide one.
Uniglide uses threaded smallest sprocket to hold the cassette in place, while the Hyperglide uses a special lockring.
To the right are two Hyperglide sprockets (bottom smallest, top 2nd smallest)
Front part of the smallest Hyperglide sprocket has small teeth to hold the lockring in place.
All the modern cassettes are of Hyperglide standard, regardless of the teeth number. In case of having a uniglide freehub, mounting a modern (available) hyperglide cassette can be done in two solutions. One is to remove smallest sprocket off the (new) hyperglide cassette and use the (worn) smallest uniglide sprocket as a lockring, filing/grinding off the widest spline of the rest of the (new) hyperglide sprockets. More complicated (probably better) solution is to switch the freehub body for a hyperglide one. Video explaining it is here: converting an uniglide freehub to a hyperglide.
This goes for 8 speed as well: 7 speed cassettes have the same sprocket width as 6 and 8 speeds, but 8 speed is a bit tighter spaced – at 4.8 mm. This means that 8 speed sprockets can be used for 7 speed cassettes, as long as the 7 speed spacers between sprockets are used.
Many cassettes have sprockets held together with 3 small rivets, but these are only for convenience when mounting and can be removed so that sprockets can be swapped.
8 speeds
The same sprocket width as with 6 and 7 speeds, but a bit tighter spaced – at 4.8 mm. This means that 7 speed sprockets can be used for 8 speed cassettes, as long as the 8 speed spacers between sprockets are used.
Sprockets are placed at 4.8 mm spacing, with each sprocket being 1.85 mm thick.
Campagnolo 8 speed cassettes have just slightly different sprocket thickness and spacing, compared to Shimano, so they can be mixed with Shimano 8 speed shifters and derailleurs, with index shifting working good. Provided that appropriate freehub body is used: Campagnolo and Shimano cassettes can’t fit each other’s freehubs – Campy with Campy, Shimano with Shimano.
Note:
As noted in the 2nd post in this bikeforums compatibility thread, “good” depends on your criteria. It won’t be perfect (table 1 lists sprocket spacing and spacer thickness and shows the difference between Campagnolo and Shimano 8-speed cassettes – Campagnolo 8-speed sprockets are spaced as Shimano 7-speed ones, but are slightly narrower, with thicker spacers between them).
9 speeds
Here there is no combining with any other standard. 9 speed cassettes have a unique sprocket thickness and spacing. Campagnolo has their own 9 speed standard, incompatible with Shimano’s.
Sprockets are placed at 4.35 mm spacing, with each sprocket being 1.78 mm thick.
10 speeds
Same sprocket width as 11 speeds, so (more expensive) 11 speed sprockets can be used as replacement, provided 10 speed spacers are used,.
Sprockets are placed at 3.95 mm spacing, with each sprocket being 1.6 mm thick.
This doesn’t go for Campagnolo. Campy 10 speed is only compatible with Campy 10 speed because of different mounting, so an individual Shimano compatible sprocket can’t be mounted.
11 speeds
Sprocket width is the same as for 10 speeds, so 10 speed sprockets can be used, provided that 11 speed spacers are used.
Sprockets are 1.6 mm thick, spaced at 3.74 mm (road), or 3.9 mm (MTB).
For more clarity on this, see below the comment by Nicolas Hanssens and the following four replies by myself and Nicolas Hanssens. I.e, based on my last measurement, and practical experience, Shimano MTB and road 11-speed cassettes have very slight differences that don’t make a noticeable difference when it comes to shifting (video explaining an 11-speed MTB cassette on a road bike pairing).
Campagnolo of course doesn’t accept any 10 speed sprockets. However, just like with 8 speeds, combining complete cassettes is possible: Campagnolo 11 speed cassettes have just slightly different sprocket thickness and spacing, compared to Shimano, so they can be mixed with Shimano 11 speed shifters and derailleurs (and vice versa), with index shifting working good. Provided that appropriate freehub body is used: Campagnolo and Shimano cassettes can’t fit each other’s freehubs – Campy with Campy, Shimano with Shimano.
With 11 speeds there is another exception: it is the only case where Shimano standards for road and MTB differ. For all the other standards, MTB and road cassette is just a marketing term, explaining the number of teeth bigger sprockets have and the difference in sprocket teeth numbers between adjacent sprockets, but with 11 speeds, cassettes really differ. 11 speed road has a longer freehub body, while MTB 11 speed cassette fits 8-9-10 speed freehub. However, sprockets, except the largest one, can be mixed and matched.
Also, SRAM makes XD 11 speed MTB cassettes that fit only SRAM XD freehubs, they can’t be mounted onto other freehub types. These cassettes can accommodate a small sprocket with only 10 teeth.
Update of summer 2018: Shimano introduced new Hyperglide+ cassette standard. These come as 11 and 12 speed cassettes. They require a special freehub body (with different spline design called “Micro Spline“), as well as a special Hyperglide+ chain. The same chain is used for both 11 and 12 speeds, but works only with Hyperglide+ cassettes. Also, derailleurs and shifters of other standards won’t work. Smallest sprocket has 10 teeth.
12 speeds
These come in four different standards.
- First one is SRAM MTB XD. These are compatible with SRAM XD 11 speed freehubs. Smallest sprocket has 10 teeth.
- As of mid-2018, SRAM has introduced NX Eagle groupset, that includes 12 speed cassettes compatible with Shimano (and SRAM) standard freehubs (for 8, 9, or 10 speed cassettes). However, they don’t allow for the smallest sprocket to be smaller than 11 teeth.Sprockets are spaced at 3.65 mm, with the smallest two placed slightly more apart to accommodate for crossed chain when using a crankset with only one chainring.
- Shimano Hyperglide+ 12 speed MTB cassettes, compatible only with Hyperglide+ chains and Hyperglide+ freehubs (using Micro Spline mounting system). Smallest sprocket has 10 teeth.
- In 2018, Campagnolo also jumped on the “more-speeds” bandwagon, introducing their 12 speed groupsets. Campagnolo 12 speed cassettes fit their (Campagnolo) 11 speed freehubs.
One exception: Shimano Dura Ace from year 1984 to 1996 (6 to 8 speeds)
Compatible only with Shimano Dura Ace shifters and RDs from the same period (6, 7 and 8 speeds), because of a different cog pitch.
Correction: cassettes are the same, what differs is the amount of derailleur movement per 1mm of cable pull/release. For a bit more details on this, see my rear shifter article’s section 5.1: “Shimano Dura Ace from 1984 to 1996 (6 to 8 speeds).”
Campagnolo Exa-Drive and Ultra-Drive
Left: Exa-Drive
Right: Ultra-Drive
Stamped circle is just an indicator helping proper alignment when mounting sprockets. No mechanical function whatsoever.
Indented grooves are used to pick the chain up when shifting to a larger sprocket. Exa-Drive indentations are designed to catch the chain pin first, then the outer plate. They work well with 8 and 9 speed Campagnolo chains.
Modern 10 and 11 speed Campagnolo chains don’t have pins protruding out of outer plates, so the newer Ultra-Drive is designed to catch the outer plates directly.
Sprockets of these two standards (with equal number of speeds) can be combined, although it will affect gear changing speed. 🙂
Table of sprocket spacing and thickness:
For a full chart including spacer thickness, total cassette width, freehub mount standards etc, see – bicycle cassette standards post.
| Cassette | Cassette pitch | Sprocket thickness |
| mm. | mm. | |
| All 6-speed | 5 – 5.5 | 1.85 – 2 |
| All 7-speed | 5 | 1.85 |
| Shimano 8-speed | 4.8 | 1.8 |
| Shimano 9-speed | 4.35 | 1.78 |
| Shimano 10-speed | 3.95 | 1.6 |
| Shimano 11-speed road * | 3.74 * | 1.6 |
| Shimano 11-speed mtb * | 3.9 * | 1.6 |
| Campagnolo 8-speed | 5 | 1.9 |
| Campagnolo 9-speed | 4.55 | 1.75 |
| Campagnolo 10-speed | 4.15 | 1.7 |
| Campagnolo 11-speed | 3.85 | 1.6 |
| SRAM 8-speed | 4.8 | 1.8 |
| SRAM 9-speed | 4.35 | 1.8 |
| SRAM 10-speed | 3.95 | 1.6 |
| SRAM 11-speed road | 3.74 | 1.6 |
| SRAM 11-speed mtb | 3.9 | 1.6 |
| SRAM 12-speed mtb | 3.65 | n/a |
| Shimano Dura Ace 6 speeds | 6.07 | n/a |
| Shimano Dura Ace 7 speeds | 5.52 | n/a |
| Shimano Dura Ace 8 speeds | 5.3 | n/a |
* See the explanation in chapter 11.
Last updated:
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I really don’t need an upgrade. Below are the existing condition:
1.since existing 8speed cassette and chain has worn out. So, need to replace these.
2. And I ride this bike in country side during monsoon and winters. So existing mechanical discs were not good at wet conditions.
Considering above two points I thought of changing it from 8 to 9spd. So what is best ? Please suggest which works out with less $$.
I personally prefer lower number of rear sprockets – the system gets more durable/robust. Especially in harsh conditions. So, if it were me, I’d stay with 8 speeds (my “workhorse” bike has 7 speed cassette and friction shifters). My dedicated winter bike (for salty roads to eat away slowly) is 1996 steel 26″ MTB with 6 speed cassette and, again, friction shifters – so no problems if cables get almost frozen – just a stronger tug. 🙂
If frozen cables are a worry (for winter riding) in harsh winters then, yes, going with Hydraulic brakes makes sense (Shimano Deore are good).
Our winters are seldom below -10 Celsius and I live in flat lands, so cable rim brakes have worked fine for me. With such winters, on hilly terrain, mechanical discs should be fine. Your bicycle’s brakes aren’t very poor quality, should work decently if properly set up (and with good and properly routed cables and housing).
Avid BB7 mechanical disc brakes are very good – and that upgrade would be relatively cheap (buying only brake calipers and discs if the current ones are in poor condition), keeping the current brake levers.
Not sure if I’ve properly explained everything, let me know if you need any more info, or clarification on something.
@Relja
While writing this I forgot to mention that even rear shifters has gone bad . So if am changing the shifters as well. What should i consider? I have decided to go with the 8spd + mechanical disc. So which shifters are good enough to my existing set up?
For new ones, Shimano makes only Altus class in 8 speeds as far as I know.
You might be able to dig out an old/left Acera shifter pair, like this one for example.
Acera are quite good.
I went friction shifting mode and sticking with it, using a pair of shifters like these ones. But got them for a cheap price. Durable – indestructable 🙂 – and work in all conditions, with any cassette I throw at the back.
@Relja
Thank you so much for your inputs, now all my doubts are clear. Finally found Acera shifters here with some local dealer. Now am waiting for bb7 callipers. Thanks a lot. ?
You’re welcome. 🙂
In my experience, Avid BB7 are probably (among) the best mechanical bicycle disc brakes.
Dear Relja, many thanks for the post. I use a Campagnolo Veloce 9-speed RD (mid-size cage). Combined with DT index shifters also from Campagnolo as well as a Campagnolo 13-26 cassette. I want to change the cassette to a wider range such as 11-34 but the largest cassette Campagnolo is offering for this model is 13-28. If I have understood your article correctly there is not much I can do about it, correct? Or can you think of any wide range cassette that could work (SRAM is the closest to Campagnolo considering pitch and sprocket thickness. Any thoughts? Many thanks, Raphael
Shimano and SRAM 9 speed cassettes have the same pitch.
Things to consider:
Rear derailleur chain wrap capacity and maximum size of rear sprocket it can handle. I explained those terms in the post about rear derailleurs.
Explanation of how to handle if the chain wrap capacity is not enough is given in the post about chain length for bicycles with derailleurs.
B screw can be turned in to allow for the RD to accept a bit larger cog that it was designed for. Sometimes, screwing it in the other way round, from the opposite side, does the trick, or using a longer screw. This depends on the RD and RD hanger design. Not always possible.
Now that’s out of the way, I would say that cassette pitch is close enough. Will it work acceptably well for your use case? Only you can tell (do let me know if you give it a try – might help anyone else with the same dilemma). For example, similar mismatch has worked for this bicycle with 11 speed Shimano drivetrain:
https://www.youtube.com/watch?v=TCmQZzeH_aU
In this case, mismatch is just over 0.15 mm, while in your case (9 speed Campagnolo vs 9 speed Shimano/SRAM), the mismatch is about 0.2 mm – could turn out to be just a tad too much. Then again, I expected the same for the 11 speed experiment – but it works perfectly fine after several months now. 🙂
Hey Team!
Looking for some help, im quite new to the cycling world but im here now and i love it. I got an old bike gifted to me, its a 1993 Specialized Allez sport. I want to upgrade the cassete to have a bigger ring, its an 8 speed 11-25, the thing is a beast. Ive read dozens of pages trying to find out for myself but i just cant sem to grasp it. Does anyone have a recomndation on what size cassste will be compatible? Does any 8 speed work? If you can even send me a link to amazon that would be great or some links to some literature that would do to! Thanks in advance!
Ty
For a useful answer, it would take a bit more information. It’s fairly simple.
Firstly, whether it is a freehub, or a freewheel cassette.
Also, in case of a freehub cassette, it depends on whether it is a Shimano compatible one, or a Campagnolo. Campagnolo cassettes generally don’t fit Shimano freehubs (and vice-versa).
Next thing to worry about is the rear derailleur capacity – and max cog size.
There is a workaround in case derailleur’s chain wrap capacity isn’t sufficient, but in case its largest acceptable cog is too small, a special adapter is needed, or a new derailleur. This depends on how the derailleur is attached to the frame.
This video shows the adapter in action, while video’s description contains an Amazon link for the adapter:
https://www.youtube.com/watch?v=TCmQZzeH_aU
So, there are some caveats and things to consider. I think such stuff is best thought out before spending any money.
I’ve provided a lot of reading material, without having answered the question. However – think it is better to be cautious, than give any wrong advice. Time spent figuring it all out, in my opinion at least, is a time well spent – making one more knowledgeable, more independent, and able to help themselves.
Having said that, this is a wild guess without any additional info, but if I were forced to guess, I’d try Sram 12-28 cassette, or, if even more teeth are needed, Shimano Tourney 12-32 – the latter one is more likely to cause problem for the rear derailleur because of the largest cog size.
In case the wheel uses a freewheel cassette – the above linked cassettes won’t fit it. Also, if it’s a wheel (hub that is) for a Campagnolo cassette, those cassettes won’t fit. Either way – more info and looking into it will be “safer”.
Hope this helps, at least a bit.
Relja