Mixed cassette cogs
 

I have a regular mavic crossmax hub (Shimano hg).
On the market there are a few cassette that require the classic hg compatibility and none of them are for 12s.

I want to upgrade my drivetrain without breaking my bank.

A good solution that popup in my mind was to keep the currently freehub body (hg) and make a custom "Frankenstein" cassette.

Let's take a look in-depth

Cassette n.1 (road bike)
11-12-13-14-16-18-20-22-25-28-32

Cassette n.2 (MTB)
11-13-15-18-21-24-28-34-40-48

Possibile Mixed cogs setup
Combination one: 11.13.15.16.18.21.24.28.32.34.40.48
Combination two: 11.12.14.16.18.21.24.28.32.34.40.48

For being more secure about the compatibility i want to use two cassette from the same brand, also i don't think I'll have some space issue since I don't own a boost frame.

Pros: with almost 100$ I'll make a custom cassette (basically very cheap if you compare to those 11s on the market). Also I'm keeping the HG freehub.

Cons: the Frankenstein cassette will weigh a lot more than a normal 12s cassette and also the scale is not amazing (for example the 32-34-40 is not very gradual as the first part of the cassette. But if the idea will work i can solve that by using a 36t sprocket instead the 34t).

What do you think?

I have done this to a couple of cassettes. It has been mixed results and kind of pain to get good shifting over the whole cassette. You are likely to end up with ramps and pins on the cogs that do not match up very well. The shifting will work, but not always crisp and clean. If you don't mind having to shift up and back, or the opposite, to get the drivetrain to operate smoothly and quietly, it's ok. That, or, there is a hesitation of a couple of seconds before the shift is made. You really have to pay attention to what you are matching up, then be willing to make a change if a cog or two are not working. Using the same brand and speed of cassettes might help. I don't see how going to 36
I did wind up with a few usable cassettes, but only one works really well with no playing with the shifting. I likely will not do it again. I do customize some 11t small cog cassettes to either 12 or 13 tooth small cog, by using the same brand cogs and replacing the 11t with 14,15,16, or 32,34 ,or whatever cog I want to fill it with. That seems to work well. Another issue is having enough cog spacers of the correct speed size. It is a bit crazy how much they cost if you do not have on hand, or access to them from someone else.
In the end, you just have to try it and see if you can get the match ups to work.
One thing that can help is getting cogs without the carrier. then you have individual, separated cogs with spacers. Miche cassettes and some Microshift cassettes come like this.

I'll add to the good reply of debiker1 and say that cog thickness varies w/ cog counts. So a 7 speed cassette has thicker cogs then an 11 speed does. The goal is to end up with the same cog to cog center spacing. Mixing spacers that are sized for one cog thickness (and total cog count) with cogs of other thicknesses will shift the C-C spacing a bit. I suggest only using cogs and spacers from the same brand of cassettes and of the same cog counts. Andy

Yeah it can be done.
The problem is the ramps not lining up.
I am going to add a cog to mine cassette.
I'm only using six of nine but I'm going to seven.
​​​​​​But I will file down the long tab so I can rotate it to any position. It is an end position one so that should work.
A middle one might be trickier

So you're going to use part 11sp & part 10sp to make a 12sp.

Are the cogs of the 11sp & 10sp the same thickness as a 12sp cog?

Barry

PS... Do you have a source for 12sp spacers?
Please share.
Thanks

I also tried to make an 11 speed Frankenstein cassette, but the shift from the smaller cog to the bigger cog across the transition between the two Ultegra donor cassettes was quite hit or miss, because the shift ramps did not line up.

Bike Forums - View Single Post - Custom 12-28 cassette

Does anyone make a non-spidered full cog 10s and 11s cassettes?

I’ve done a lot of mix-n-match up thru 9 speed with cassettes that have full cogs.

I haven’t had a ramp issue if the correct cog is used. Some have a single ramp for 1t differences and others have 2 or more ramps for larger cog to cog gapping. I once tried a 1 ramp 14t and it was considerably slower shifting going from a 12t.

John