This post addresses bicycle crankset compatibility in terms of mixing various speed cranksets with other components. For example: an 8 speed crankset on a bicycle with 10 rear sprockets and a 10 speed chain (a), or a triple chainring with a front derailleur (FD) constructed for double chainrings (b). It will also address mixing road cranksets with MTB FDs and vice versa (c).
Before you start, to avoid any misunderstanding:
please take the 5 minutes needed to read the compatibility articles use instructions.
Separate posts explain: standards of bottom bracket (crankset) bearings (and axles), as well as bottom bracket compatibility). That will not be taken into consideration in this post, but when acquiring a crankset, make sure that it’s bottom bracket (BB) standard is one that can be mounted on the bicycle frame.
In the post about FD compatibility, other factors important when matching FD and crankset are described. So, even if number of speeds and type of crankset and FD are the same, those factors should also be matched. In short: FD cage shape and number of large chainring teeth it is designed for should match the teeth number of the largest chainring on the crankset it is combined width. Detailed explanation of things one should pay attention to and try to match are listed in the post:
Compatibility – front derailleurs
1. Different number of speeds for crankset, and the cassette
Typical example: can a crankset for 9 speeds be used with a bicycle that has 11 speeds (rear sprockets) and an 11 speed chain (for 11 sprockets)? Or vice versa: can a 10 speed crankset be used on a bicycle with 8 speeds?
All the “speed” chains have almost the same inner diameter (roller width). Despite the fact that chains for more speeds have thinner plates and are therefore narrower (on the outside) than chains for less speeds, the inner width is the same. For detailed explanation look here: Compatibility – chains.
Because of this, teeth thickness of crankset chainrings doesn’t vary much. Also, adjacent crankset chainrings have great difference in diameter and are not as tightly spaced as rear sprockets. So there is no risk of chain, being to wide, to get stuck between two chainrings.
All this enables crankset chainrings to be freely combined with all kinds of chains (and, over the chain, various numbers of rear sprockets). The only complication is the thinner cage of the FDs designed for more speeds. This means, if using a (wider) chain for less speeds, chain will rub the cage with less cross chaining then if a wider cage FD was used. Cross chaining is not advisable anyway, so one can consider this and early(er) warning. Explanation of gear changing and cross chaining is here:
Bicycle gear ratios
Exceptions to this are single speed chainrings, made for wider, 1/8″ thick chains (they won’t work with multi-speed chains) and Shimano IG chainrings (that work only with chains for up to 8 speeds).
2. Mix-matching various types of cranks (chainrings)
2.1. Combining double chainring cranksets with triple FDs
Explanation of important attributes and differences of FDs can be found in these posts:
Front derailleur
Compatibility – front derailleurs
Triple FD has a longer cage (than a double FD), with inner part of the cage being a bit lower, to catch the chain off the third, smallest chainring. If the two chainrings of a double don’t have a big difference in number of teeth (14 or less), triple FD should work just fine on a double (with correct setup of the limit screws and cable, of course). Typical examples are standard road doubles 53-39 (14 teeth), or 46-36 (10 teeth) – a typical cyclo-cross crankset.
If using a popular “compact” crankset, with a large difference in number of teeth between the big and the small chainring, like 50-34 (16 teeth), or 46-30, shifting will be slower, with more possibility of dropping the chain when shifting onto the smaller chainring.
However, even if chainring difference is large, front shifts are usually quite rare (compared to rear shifts), so even then it might work acceptably well (depending on one’s criteria).
2.2. Combining triple chairing cranksets with double FDs
The biggest problem with this combo is that double FDs don’t have a long enough cage, with inner part lowered enough to catch the chain off the smallest, third chainring.
The quality of this pair functioning is affected by the following two factors:
- The lower the difference in teeth number between the largest and the smallest chainring, the better.
For example: 48-38-28 (20 teeth difference) is better than 44-32-22 (22 teeth difference).
Or: 50-39-30 (20 teeth difference) is better than 53-42-30 (23 teeth difference). - The number of large chainring teeth the FD is designed for should match the number of teeth of the largest triple chainring, or be slightly lower.
For example: FD for 50 tooth chainring on a 50-39-30 triple.
Or a FD for a 46 tooth chainring on a 48-38-28 double.
Bad idea is a FD for a 53 tooth chainring on a 44-32-22 triple.
2.3. Combining MTB cranksets with road FDs and vice versa
Road and MTB cranksets have slightly different chainring spacing. Still, this doesn’t cause much problems even to shifters and FDs when mixing them, as is explained in these two posts:
Compatibility – front shifters
Compatibility – front derailleurs
Difference definitely doesn’t bother the FDs. If the shifter, cable and screws for limiting movement are properly set, there won’t be any problems.
Related post – Bottom bracket compatibility:
Compatibility posts are also available in eBook (printable and Kindle) and paperback editions on Amazon:
If you have any questions (or additions and corrections), please use the BikeGremlin forum’s compatibility section:
https://www.bikegremlin.net/forums/bike-compatibility/
The existing comments posted under this article (questions and answers) have been moved to this BikeGremlin forum thread:
https://www.bikegremlin.net/threads/compatibility-09-cranks-ets-article-comments.119/
Spare wheels are a handy thing. Especially if riding daily, year long and in bad weather. In case of any damage – there’s a spare wheel while the damaged one is rebuilt.
Also, if switching from fair to poor weather (and/or snow) tyres, one can do so quickly, at one’s own convenience (weather in Serbia is crazy, as in ranging from nice and sunny in the middle of the winter, then snow the following week, then sunny again).
Reja,
Man, I totally understand English is not your native language. After reading your comment a couple of times I totally agree especially in regards to the 48-28=20 is far less taxing than 44-22=22. But I think a better example is 42-22=20 vs 44-22=22. That would’ve made more sense even though you were on par with 48-28=20. That’s all.
I see your point and it is a fair one. For purely educational purposes, it would be easier to understand if I had used 42-32-20 as an example. However, I opted for using (more) widely available cranks (and chainring tooth counts) for the examples.
Your feedback is very much appreciated. Will give it some more thought. For now I’d keep the examples as they are.
Hi Reja,
As I was reading the article one part of it didn’t make sense to me and its this passage:
“The lower the difference in teeth number between the largest and the smallest chainring, the better.
For example, 48-38-28 is better than 44-32-22.
Or: 50-39-30 is better than 53-42-30.” (https://bike.bikegremlin.com/1619/bicycle-crankset-compatibility/#comments)
There’s nothing wrong with the second example but the first example makes no sense, and the example is contradictory of itself a 48-38-28 crankset is not better than a 44-32-22. You’re saying the opposite of what you mean you’re really saying: “The higher number of teeth between the largest and smallest chainring the better.” When what it really should say: “The lower the difference in teeth number between the largest and the smallest chainring, the better, for example, 42-32-22 is better than 48-38-28.” I would also add another example like 40-30-20 is better than 42-32-22. Also list your examples 1,2,3 or A,B,C. Just saying.
English is not my native, but what I tried to say is this:
44-22 = 22 teeth difference
48-28 = 20 teeth difference
20 teeth difference is less taxing on a double FD than 22 teeth difference.
The lower the teeth difference, the less likely a double FD is to have problems working with it.
I have an old mtb triple crankset FC-MT60 and am having trouble shifting to the lowest chainring using a FD7803 triple 10 speed front derailleur, but it’s not moving the chain over enough and can’t move further as it hits the frame.
There are some spacers I can remove between the rings – what is the right distance between chainrings to adjust it to?
If the FD can’t move any closer to the frame, in order to shift to the smallest chainring, then I would first see about the chainline (how to measure the chainline, and how to set a correct one).
Suppose that using a longer BB axle would solve the problem.
Hello,
I have a shimano FC TY301 48-38-28T on a 3×8 gear trekking bike and would like to keep it while I upgrade to 3×9 gear. Whould that be possible? I have already bought a SHIMANO ALIVIO RD-M4000-SGS 9sp MTB Rear Derailleur and a SHIMANO CS-HG400 9SP 11-32 Τ. Should I opt for a 116 or 118 HG chain by yhe way?
Sincere regards,
Harry – Athens
Hello Harry,
Those cranks should work fine with the 9-speed drivetrain.
As for the chain length – it depends on the bicycle. See my article about chain sizing for bicycles with derailleurs.
Relja
Hi Reija
I bought a Shimano 12 speed rear to upgrade from a 3×9 Shimano Deore group, I’m using the same crankset and 40 tooth chainring at the front (designed for the 3×9) but I moved the large chainring to the inner side of the spider and even added some washers to move it as far in as possible and get a decent chain line. The question is: Are 12 speed front chainrings narrower by design than a 9 speed? I feel a little more strain on the system when using the largest cog in the rear and it seems to comes from the front. That stresses me.
Hi Louie,
I like to joke that 1x drivetrains often “solve” problems that wouldn’t have even existed without them. 🙂
Generally: they work a lot better with narrow-wide chainrings designed for the 1x drivetrains.
This especially helps reduce (prevent?) any chain drop from the front chainring.
I’m not 100% sure I fully understand what you mean by feeling a “little more strain on the system.”
What I would check first is how tightly the front chainring is attached.
The next thing to check is the chainline.
The largest rear cog is used with a lot of torque, and if the front chainring isn’t aligned at least with the middle of the cassette (if not even a bit more inwards, towards the frame), I would expect the chain, and the chainrings to suffer and just not feel right under the pedal as you push down on it.
Regarding the front chainring width:
Some manufacturers of narrow-wide chainrings state they are compatible with 9 through 12-speed chains.
Like this from Blackspire.
I haven’t measured Shimano 2×12 chainrings to tell if they are narrower than the 9-speed, or even the 11-speed chainrings, but I don’t think that chainring width is the problem cause in this case (or, in other words: I’d first check the chainline).
Relja