Note: this article explains compatibility in terms of rear sprocket mounting and proper gear shifting. For other important facts about rear hubs, read the following articles:
Rear hub
Freewheel vs Freehub
Before you start, to avoid any misunderstanding:
please take the 5 minutes needed to read the compatibility articles use instructions.
Relevant BikeGremlin forum compatibility section, and a discussion about freehub compatibility.
Compatibility categories will be sorted by number of rear sprockets. It is important to note that there are three major rear freehub standards – a) Shimano standard supported by most other manufacturers (SRAM as the biggest one), b) Campagnolo standard and c) SRAM XD standard that accepts cassettes with the smallest sprocket of only 10 teeth.
Campagnolo uses different spline design, so Campagnolo cassettes can only fit Campagnolo freehubs, while Shimano cassettes will only fit Shimano compatible freehubs.
a) SHIMANO standard
Stated compatibilities also go for SRAM (and most other manufacturers’) cassettes with the same numbers of sprockets – they’re compatible with Shimano, except the SRAM XD cassettes.
6 and 7 speeds, freewheel
All the current (since the year 1990) freewheel hubs are compatible with all the 6 and 7 speed freewheel sprockets.
and freewheel sprockets that are screwed onto it.
7 speed freehub
7 speed freehubs accept 7 speed cassettes.
Cassettes with more sprockets can also be fitted onto 7 speed freehubs, but some sprockets need to be removed. The smallest sprocket must never be removed since it is profiled to accept the lockring holding the cassette in place. When removing sprockets, if it is not the largest one, expect shifting between the two adjacent sprockets left to be a bit sluggish, since sprocket teeth are profiled to allow faster shifting, but removing one sprocket messes up that pattern.
8, 9 and 10 speed cassettes can be used if one sprocket is removed.
11 speed MTB cassette should also fit with just one sprocket removed, but here, along with the smallest, the biggest sprocket also mustn’t be removed – it is specially designed to take up less space on the freehub body.
11 speed road cassette – two sprockets need to be removed. Unlike with 11 speed MTB, here the biggest sprocket can be removed.
8-9-10 speed freehub
It accepts all the cassettes, except 11 speed road ones.
When placing a 7 speed cassette on such freehub, a 4.5 mm spacer needs to be placed before the cassette. Then check if the smallest sprocket engages the freehub splines. If it doesn’t, check if the largest sprocket has gotten over the spacer correctly (the spacer mustn’t be too “tall”). If this doesn’t help, try using a bit narrower spacer, to make sure the smallest sprocket is slit onto the splines properly.
This is important whenever mounting the cassette: smallest sprocket should engage the freehub splines, so it doesn’t turn freely, but it mustn’t be aligned with the freehub body all the way – it should be a bit “taller”. Otherwise lockring won’t be able to lock the cassette in place. If the last sprocket sits too deep, add a (thicker) spacer. If it turns freely, remove a spacer (or one sprocket, if there are no spacers used).
Pictures above don’t show a case when there are too many spacers (or they are too thick) – then the last sprocket would not be able to sit on the freehub splines properly.
8 and 9 speed cassettes are placed directly, without any spacers (9 speed cassette has narrower and more tightly spaced sprockets, so it has the same overall width as an 8 speed cassette).
10 speed cassettes have even narrower, more tightly spaced sprockets, so their overall width is actually smaller than that of 8 and 9 speed cassettes. That is why placing a 10 speed cassette on a 8, 9 and 10 speed freehub requires a 1 mm wide spacer.
10-speed cassettes with a built in 1 mm spacer!
To make things more complicated, Shimano “builds in” the spacer on some 10-speed cassettes. For example: Tiagra 10-speed (road) and many MTB 10-speed cassettes have a bit wider spider that carries the largest cassette chainrings, so there is no need for adding the 1 mm spacer.
11 speed MTB cassette is put straight on, just like 8 and 9 speed ones.
11 speed road cassette doesn’t fit this freehub. One sprocket needs to be removed (not the smallest one because of the lockring). Then a 1 mm spacer needs to be put before the cassette (do check alignment and put a thicker spacer, or remove the spacer if it all fits).
I demonstrated how to check whether spacers are just a bit too thick, or narrow in this video (watch until the end).
10 speed freehub
Shimano also used to produce special 10 speed only freehubs for a while, which are a few mm narrower than 8 and 9 speed freehubs. Only 10 speed cassettes can fit these freehubs. 10 speed cassettes are mounted onto these freehubs without any additional spacers. There are also 10 speed freehubs with aluminium body. Splines are taller, so that more material comes in contact with (narrower) 10 speed sprockets so they don’t cut into the freehub body under load. These hubs can not fit 7, 8, or 9 speed cassettes because of taller splines.
Source: VÉLO7 – veloseven.com
Another “catch” is that the newest 10 speed cassettes, Shimano Tiagra 4700 model, won’t fit these freehubs, because they are not cut deep enough for the taller splines. Just to make things more interesting. 🙂 The same goes for many 10-speed MTB cassettes.
In practice, when a term “10 speed freehub” is used, it is usually meant the 8 and 9 speed compatible one, not the exotic 10 speed only Shimano stuff!
11 speed road freehub
Since MTB 11 speed cassettes can be mounted on the 8, 9 and 10 speed compatible freehub, this one is meant for road 11 speed cassettes only.
8 and 9 speed cassettes can be used with a 1.85 mm wide spacer. Same goes for 11 speed MTB cassettes (thanks to Christophe for the feedback).
10 speed cassette requires an additional 1 mm wide spacer (along with the 1.85 mm wide one) – just like when putting a 10 speed cassette on a 8-9-10 speed freehub – but not always: for catches and caveats, see the 10-speed freehub section above and the 8-9-10 speed freehub section.
7 speed cassette will require 4.5 mm spacer, in addition to a 1.85 mm wide one (used when mounting 8 and 9 speed cassettes).
11 and 12 speed MTB XTR M9100 freehub
From summer of 2018, new standard, completely different from all the others. Freehub splines and cassettes are mounted differently and can’t be combined with other standards.
New cassette teeth design is called Hyperglide+, while the new mounting interface is called “Micro Spline“. It has 23 deeper splines, where Hyperglide has 13. Detailed explanation is at the following links: Hyperglide+ freehub and Hyperglide+ cassette.
b) Campagnolo standard
Campagnolo hubs are compatible with Campagnolo cassettes only. Even there, they have different standards, by generations and by numbers of speeds, like it is explained here:
7 and 8 speed freehub – old standard
7 speed freehub is about 5 mm narrower, but all the old 7 and 8 speed cassettes will fit both 7 and 8 speed freehubs.
8 speed Exa-Drive freehub
Current Campagnolo 8 speed standard. There is also a discontinued 8 speed standard for titanium cassettes, that are no longer produced.
9 speed freehub – old standard
Standard for old, Exa-Drive 9 speed cassettes.
Wide ridge at 5 o’clock and a stepped ridge at 7 o’clock.
9-10-11-12 speed freehub – current standard
Current Campagnolo standard – suitable for all the modern Ultra-Drive cassettes, whether they are 9, 10, or 11 speed (12 speed as well from 2018).
Right: Campagnolo Ultra-Drive cassette freehub
Source: www.eqnx.co
Since Campagnolo is next-to-impossible to come by in my country (Serbia), I can’t provide much info on their newer (13-speed) stuff, but this post on the CycleChat forum seems to be correct and reliable, and that’s the best info I can offer on the topic for now:
https://www.cyclechat.net/threads/trying-to-clarify-what-11-32-means-re-cassette.294834/page-2#post-7096287
c) (SRAM) XD 10, 11 and 12 speed MTB standard and 11 speed road
Cassette carrier (freehub) has been redesigned and accepts cassettes with the smallest sprocket of only 10 teeth!
Right: Shimano hyperglide compatible freehub.
XD freehub standard accepts only XD cassettes. There are 10, 11 and 12 speed cassette versions (same XD freehub body).
Many wheel and hub manufacturers make XD compatible freehub bodies that can be screwed onto the hub instead of the old Shimano compatible freehub. Unfortunately, as far as I know, Shimano is not among them for now.
As of mid-2018, SRAM has introduced NX Eagle groupset, which 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.
SRAM has also made an XD road freehub, named XDR (XD Road), that is wider by 1.85 mm than the XD freehub. 11 and 12-speed XD cassettes can fit XDR hubs with a 1.85 mm spacer added (like when mounting a 10-speed Shimano cassette on an 11-speed Shimano road hub). On the other hand, XDR cassettes won’t fit XD hubs, because they are wider by 1.85 mm, so will stick out on the outer end too much.
Last updated:
Originally published:
Related post – Bicycle cassette compatibility:
Compatibility posts are also available in eBook (printable and Kindle) and paperback editions on Amazon:
The existing comments posted under this article (questions and answers) have been moved to this BikeGremlin forum thread:
https://www.bikegremlin.net/threads/compatibility-03-rear-hubs-article-comments.115/
Thanks for the great info, it actually is useful.
Wrote it for myself – too many stuff change, wanted it all in one place to remind myself when I need it. 😀 Glad you find it useful too. 🙂
So is the 11speed road cassette 1.8mm wider then a 10speed MTB cassette?
Yes. A Shimano 11 speed road cassette is about 1.8 mm wider than a 10 speed cassette.
Just to note that for 10 speed cassettes – there’s no difference between road and MTB ones: same width, pitch and sprocket thickness.
I have formula hub 142×12 with non anti bite guard freehub feature. Now I want to replace it with different manufacturer Freehub Body but same measurement 142×12. Is it compatible?
That would depend on the profile of the freehub part that gets onto the hub. These things differ from model to model for all I know.
So do check, compare, but it’s not just the axle and width, but also the number of ratchets and the shape of the part going towards the hub.
Not sure if I’ve explained properly, let me know if You need pictures and more clarification.
Thanks relja for the help.
Anytime. Was in a position to ask for help, glad to be able to help others now. 🙂
Can I use a campy 10 speed wheel and switch to a 12 speed free hub?
According to Campagnolo, yes. That is – 10 speed wheel could fit a 12 speed cassette according to Campy docs.
11 speed Campagnolo cassettes fit 9 and 10 speed Campagnolo freehubs. Source:
https://www.campagnolo.com/US/en/Support/can_an_11s_sprocket_set_be_mounted_on_a_campagnolo_9_10s_compatible_wheel
While 12 speed cassette takes the same space as 11 speed one. Source:
https://www.campagnolo.com/US/en/Components/super_record_sprockets
I haven’t tried this, not even seen a 12 speed Campy live yet, unfortunately.
What is the widths of the 10, 11 and 12 speed driver bodies for the XD compatible drivers?
I don’t know.
Will edit the text though. I think I see where the confusion was.
The body is the same, for any XD cassette used. No different body widths.
Thanks, this is a really helpful article. Sheldon Brown’s compatibility webpage is also helpful, though it is mostly text and a picture can help a lot.
–> question about free hub bodies. There are several shimano hub bodies in the 8-9-10 family available at numerous retailers and I can’t figure out which one to buy. I am trying to mount on an older deore XXT mtn hub to convert it from 6-7 to 8-9-10. The older hub never shows up in the listings online. I tried to use a freehub I had and I would say it puts the largest cog perilously close to the spokes coming out of the flange. I could make a thin shim, but I was wondering if there is any documentation available that characterizes the width of the free hub drivers from the hub seat to where the cogs start? Or an overall width dimension so I can subtract off the cog region?
Thanks
For all I know, Shimano freehub body width comes in several dimensions (sorted from narrowest to the widest/longest):
7 speed
10 speed only (sold/made for a relatively short period)
8-9-10 (any) – 11 (MTB only) speed
11 speed road
So old 7 speed freehub will be too narrow to accept 8, 9… speed cassettes. The main concern being the lockring not having enough threads to get properly threaded and engaged.
Though I never tried replacing a 7 speed freehub mechanism with an 8-9-10 one, on a 7 speed hub. It is possible that the flanges are put too close for the 8-9-10… speed cassettes to clear the spokes. But I can’t confirm that.
I can’t figure from the comment what exact model of hub you have, which replacement freehub body you are considering placing on it and which cassette is to be tried on. That info might help.
It’s a deore XT FH-M732 mtn hub, 135mm axle. I am indeed trying to put an 8/9/10 body on this hub. Based on the flanges, which are approximately 60mm apart, I think it should be close. There is a lot of room with a 7 sp cassette. I may need a small shim under the free hub, depending though. Wish I could find drawings with measurements for the free hubs shimano makes today – there appear to be 3-4 different shapes with slightly different offsets from the mounting face.
A few notes, just in case:
When adding a wider freehub body, hub’s OLD will change. Solution would be making the left hand side spacing a bit narrower (replacing a wide spacer with a narrower one helps).
Don’t have the measurements of freehub widths – but will measure when I find the time (adding this to to-do list).
Likewise, I also think that freehub attachment profile/standards differ between models, not all will fit all, even “within” the Shimano brand.
As for the spacers, with an 8-9-10 speed freehub, only if using a 10 speed cassette, a spacer must be added (1mm wide, often provided with the cassette). 8 and 9 speed cassettes don’t need any spacers. There’s definitely no room to add them with those cassettes, even if one wants to.
Thanks for your comparison and detailed article, this is very helpful! 🙂
Hey,
Excellent article ! So useful !!!
Will also be super useful to have a measurement of freehub. I am helping in a bicycle workshop and we have a box of freehubs but always take some time to figure out what models they are.
Just to add that it is not clear that you can use a 11s speed MTB cassette on the 11 speed ROAD freehub with à 1.8 mm spacer.
Thanks for the great work !
Hi,
Thank you very much for the feedback. I’ve edited the article to be more clear now. 🙂
As for the measurements, I have made a hub dimension spreadsheet, noting the dimensions important for wheelbuilding.
Do you think any other dimensions should be included?
Yes
Size of freehub : (From kstoerz website)
7s freehub – 30.9 mm
8-9-10s (and 11s MTB) freehub – 34.95 mm
10s only freehub – ?
11s freehub ROAD – 36.75 mm
Otherwise I use this website for hub size. And calculate with Roger Musson like you do.
https://www.kstoerz.com/freespoke/
Thanks Christophe, that’s a great resource (Kstoerz). I’ll link to it from my pages for hub, and rim dimensions.
Useful page! I am stuck with a Trek Marlin 7speed and trying to figure out if I can improve it or if I should just get a new bike. I was short sighted and changed to 1x in front, and now I live somewhere with more hills and wish I had lower gears. I had heard about the “8 of 9” or “9 of 10” method where you could supposedly fit other cassettes on this 7 speed hub. Your page here helped me understand it even a little better (I think). This is the first place that I heard the key information that you can’t just remove the smallest gear – I had assumed that would be the easiest way to do it! This leaves me wondering, how many other choices do you have though for other gears to leave off? How often does a cassette come with more than the smallest gear not completely attached to the cassette? Or in the case of wanting to remove the largest gear (aside from 11 speed where you should not), how would you ever take off the large gear? Aren’t these usually riveted together? Of course I am speaking of lower-end budget components; I have seen that a higher end cassette can come apart in many more pieces. Basically if I wanted to find an 8, 9, or 10 speed casette to use, but the rule is that you can’t just leave off the smallest gear, do I need to make sure it has the second smallest gear as a separate piece? I wouldn’t want to remove the larger gears anyway since that is where I am looking for extra range.
My choices are to fit something on the 7 speed hub, buy a new rear wheel that has a hub for 8/9/10, or just start thinking about my next bike. (I’ve read conflicting information about just trying to get a longer hub body on the original wheel, seems like you shouldn’t really do that as the wheel dish isn’t correct etc). I’d like to keep the 1x up front so I’m not considering going back to a front derailleur.
Hi,
There are several solutions to this gearing problem. I’ll number them for easier reference in case of any follow-up questions:
1) Custom cassette.
Some cassettes have the largest sprocket go all the way to the freehub. While others have the largest 3, or more sprockets stuck together on a spider.
For the former ones, you can drill out the pins, rivets, or unscrew the bolts – whatever is holding the sprockets together – and use the sprockets “separately,” as you please (just don’t forget to put a spacer between every two sprockets 🙂 ).
My road bicycle has 53-42 cranks, so I just took an un-worn 34-tooth sprocket from an 8-speed cassette and put it first on the freehub, to allow me climbing long, steep climbs. It took place of a 25 tooth sprocket. The next, 23-toothed sprocket got replaced by a 28-toothed one, to make the gap a bit smaller and allow shifting. Most of the cassette is “edited” to make it “slower / easier,” but without such huge gaps on the “faster end” of the cassette. For the smallest sprocket, I went with a 12-toothed one (that’s the largest readily available) and used a matching locknut for a 12-T sprocket.
Here’s a video, in my native (Serbo-Croatian) – you can play some music and just watch what I’m doing 🙂 (I’ll make a video in English once I find the time):
disassembling a cassette – Serbo-Croatian version
– You can use Google translate for the video description, because it contains a Table Of Contents, so you can skip to the parts of interest, not have to sit through the whole video.
Lower end cassettes, especially the 8 and fewer gear ones, often have sprockets going all the way to the freehub.
2) Triple, or double cranks
This is a good solution as well. You would need to find a front derailleur and a shifter. In my city, 2nd hand ones can be sourced relatively cheaply. I strongly prefer friction shifters, but I know it’s not everyone’s cup of tea.
If a frame fits you, you can mount practically whatever you want on it and make it an effectively new bicycle, matching your requirements.
Relja
Hello ….. I bought Pro Lite bracciano A42W wheels where the freehub Campagnolo is installed, and I have Shimano all the gear in the bike, now the question is whether I can change the freehub from Campagnolo to Shimano or do I have to replace the entire hub, Thank you and best regards.
Chris
Hi Chris,
Some hubs have interchangeable freehubs (DT Swiss models come to mind).
For some, a Shimano freehub will fit, thread on – for having the same interface.
Howerver, I’d say that for most hubs – the answer is no. 🙁
I would recommend posting the question (with your hub model) on bikeforums.net. If someone’s done that, they might share how and what freehub they used.
Relja
Your site might very well be the most informative site on the internet. It is certainly the best and most well-written information on bike maintenance that I have ever encountered and I really appreciate it. I just want to say thank you. Your information really helped me and my gratitude is much more than I can express in words.
Hi Sean,
Thanks – glad it could help. 🙂
Relja
Thanks for explaining Campagnolo Exa-Drive , old and current. I do have a question, now that I know the type of freewheel hub I have on a set of wheels I purchased. Will an 8 speed Miche Primato 8 speed cassette fit onto the exa-drive splines? Thanks
Hi Ian,
For all I know, Miche makes both Shimano, and Campagnolo compatible cassettes.
“Primato 8 SH” is Shimano compatible, while “Primato 8 M” is Campagnolo compatible.
However, I haven’t had any first hand experience with Miche Campagnolo-compatible cassettes.
Exa-drive is the current Campagnolo’s 8-speed standard and I think that’s what the current Campagnolo-compatible 8-speed cassettes fit.
Relja
Thank you Relja. I decided to go for a Campagnolo 8 speed knowing it will fit. Had hoped to get a 13-26 but they are fairly difficult to find and are more pricy, but I have a 13-21 that I purchased. Will have to keep away from the hills when I ride the bike with this drivetrain!
I’m sticking with the old-school 53-42 cranks, but at the back, I’ve switched to a 13-34 cassette years ago.
Gravity seems to have increased a bit over the past decade… 🙂
Still got the down-tube friction shifters, so I can make custom cassettes from the spare parts (not all the sprockets get worn on every cassette I replace), mixing 7 and 8 speed sprockets.
A bit of a Frankenstein, but it works. 🙂
Good day Relja. The mysteries of Campagnolo Exa-drive cassettes keep coming up. I received the cassette that I ordered, but the lock ring threaded section, does not fit the threaded section on the hub of my wheel. The lock ring I received measures 25 mm diameter and it appears I need a lock ring more like 28.5 mm diameter. So my question, Are there two different diameters for the Exa-drive lock ring? The seller may have sent a Lock Ring for Ultra-Drive. What can you tell me in this regard?
Hi Ian,
It sounds like you got an old 9-speed standard lockring – for the 9-speed Exa-Drive.
The newer 9-speed cassettes are Ultra-Drive.
8-speed ExaDrive is over 28 mm, as you’ve measured (not sure about the exact locking thread diameter, but I’d bet on 29 mm for the lockring threads outer diameter).
I did some googling since I have no Campy cassettes nor freehubs at hand.
See this Campagnolo tech. document on page 61 (in a PDF reader, it’s page 55 as shown on the page).
It says that old 9speed lockrings have a 26 mm thread diameter, while the newer 9-speed standard is 27 mm.
And it says 29 mm for 8-speed.
Relja
Thanks for the article, it is very informative.
I am inexperienced but thought I’d give a try to fix an old gardin my gf owns.
It has campagnolo hubs on araya/ambrosio elite rims.
Shimano 600 levers and components:
7-speed freewheel cassette (11-23) and biopace 52/42 crankset. Friction/SIS downtube shifters.
I don’t intend to change the shifters for now, but I was wondering if we could try to give a few more range to the gears for the climbs in Vancouver’s coast. If at all possible, what would be the simplest approach? Is there an 11-34 (or even 11-42) cassette I could fit in these hubs, or would it need new wheels/hubs on top of a new cassette?
Perhaps a lower grear crankset is another way to go, but she loves the biopace!
Thanks in advance!
Hi Noe,
My road bike has 53/42 BioPace cranks, and I have a spare, like-new, set stashed in my garage. 🙂
It’s nice, but the gravity seems to have become stronger over the past decade… for me at least – the younger lads don’t seem to be affected!?! 🙂
The way I’ve solved this was by sticking with the friction shifters and making a custom cassette using a freehub wheel, making it go:
14-15-17-21-23-28-34
The last two huge jumps in tooth count are just right for the steep climbs when I want one shift to make things a lot easier.
For a 42 T largest sprocket, at least on my bike, I’d most probably have to swap the rear derailleur for an MTB one or use a derailleur hanger extender (WolfTooth is known for making those).
I’ve seen 12-34 7-speed cassettes. I’ve also seen 12-34 freewheels. Not sure about 11-42, at least with (only) 7 speeds.
Relja
Thanks for taking the time with all the details, Relja.
I hear you about gravity! I am going to try and make it work with the current 7-speed cassette for now. If all goes well then perhaps I can try to switch the hub and make a custom cassette.
Great article and discussion.
Will a SRAM 12 spd AXS road cassette fit on a Shimano 11 spd road freehub?
Or is there a freehub replacement that will accept the SRAM 12 spd cassette for this wheel?
Hi Jens,
The safest bet is to check manufacturer specifications for the particular model.
As far as I know, 12-speed AXS road cassettes require an XDR freehub, so they aren’t compatible with Shimano freehubs (see the freehub compatibility article for more details).
Depending on the rear hub model, some manufacturers offer replacement freehub mechanisms for different standards. But that also needs to be checked with the rear hub manufacturer – whether replacements are available.
Generally speaking, manufacturers are paying a lot for marketing, to convince us we need to get the latest & greatest stuff (11+ speeds at the back, 1 chainring at the front, disc brakes etc.).
And, they are working hard to make it very, very difficult to mix-match stuff from other manufacturers. Some companies produce various products to help sort out the incompatibilities, but they aren’t mass-produced and often cost a lot – like Jtek ShiftMate gear shift adapters (link to their website), DT Swiss XDR freehub conversion kits (Amazon affiliate link) etc.
Relja
Does anybody know if I can put a shimano freehub on Cube attain race road bike ( cube branded hubs ). For example this Shimano: https://bike.shimano.com/en-EU/product/component/shimano/FH-RS470.html on this bike: https://www.cube.eu/en/2022/bikes/road/road-race/attain/cube-attain-gtc-sl-greyncarbon/
If the website info is correct, the factory rear wheel is Fulcrum Racing 77 DB.
That’s 142×12 mm thru axle, so that Shimano hub should fit.
Just keep the original axle for mounting the wheel, that’s generally frame-specific (intend to write an article on that).
Of course, if you have the bike – measure to confirm (the dropout spacing and the axle diameter).
Hi. Nice info!
Do you know the spacing and width of the new Shimano Linkglide 10 and 11 speed?
Hi Sid,
Will know as soon as I get my hands on one. 🙂
As I understand, if I upgrade SRAM XT hiperglide freehub mounted on fulcrums wheels I just need to buy sram XD freehub and fit it… Why I found SRAM XD freehub with details about hubs brands? It’s confusing me…or I need to search XD freehub compatible with fulcrums wheels particularly?
Hi Ricardo,
Short answer:
Yes, you need to find a Fulcrum compatible freehub with a SRAM XD cassette mounting system (if you wish to run SRAM XD cassettes).
Explanation:
Freehub to hub mounting system and cassette to freehub mounting system are two separate compatibility concerns.
Generally, not every freehub can be mounted on every hub. I.e. freehub to hub mount needs to be a matching one. It usually depends on the manufacturer (i.e. DT Swiss hubs require DT Swiss compatible freehubs). Sometimes it even depends on the particular model (i.e. not every Shimano freehub will fit every Shimano hub).
Cassette mounting system on the freehub (Shimano Hyperglide, Hyperglide+, SRAM XD etc.) is a separate compatibility concern. That needs to match the cassette you intend to use.
I’m getting on a bit my hybrid bike has 2×9 gearing and the wheels are the same size as a road bike. My question is, could I put a modern 12 speed wheel on my bike and just buy a derailleur a 12’speed cassette and lever and go from 18 gears to 24 gears
Hi James,
To switch to a 2×12 drivetrain, you would need the following:
1.
A rear hub that can take a 12-speed cassette (depending on which one you opt for), and that also fits your frame.
If I had to guess, I’d suppose your frame has 135 mm rear dropout spacing (or 132.5 mm), in which case you’d need a hub that has a 135 mm OLD (Over Locknut Distance).
If needed, see chapter 5 (and 5.1) in my article about bicycle rear hubs for more details.
2.
A cassette matching your hub (there are different mounting systems, such as SRAM XD, and Shimano Microspline).
If you opt for a Shimano Hyperglide 12-speed cassette (not a Hyperglide+), it should fit right onto your existing 9-speed freehub.
Larger sprockets are designed to “overhang” the right hub flange, as their diameter is pretty large (36 teeth on the largest and similar), so that’s how they found the room to fit.
3.
A matching 12-speed chain (if you opt for some of the more “exotic” cassettes such as Shimano Hyperglide+).
4.
Matching 2×12 shifters and derailleurs.
5.
If you go with Shimano Hyperglide+ or SRAM AXS (road stuff, with their “flattop” chains) it will be a good idea to also buy the matching cranks, as chains and chainring teeth are designed to work well with each other, and don’t play as well with the “normal” stuff.
What you would get in the end is most probably only 2 or 3 more gear choices between your highest and lowest gear. I.e, gear ratios a bit more tightly packed (a video where I touched upon why front and rear shifters don’t give a simple multiple of their count in different gear ratios). And a split-second faster shifting. None of that really matters for anything except competitive cycling in my opinion and experience – it just costs (a lot) more. In other words: if your current drivetrain is lacking something, depending on what it is, there may be simpler ways to fix that. I think it’s fair to note and disclose that info – so that you know what is reasonable to expect and make an informed decision (i.e. it’s perfectly fine to go with the new, expensive stuff if you wish, it’s your bike and your choice).
Relja