Mixing cogs from different speed cassettes

[richj8990]

I was starting to mess up a different thread with a bunch of gear ratios so let's just put this separately.

A lot of talk about 11T wearing out the chain fast on mid-drives. And the chain wearing out 11T fast. Most of these cassettes start out 11-13-15. You can buy 11, 12, 13, 14, 15T cogs individually, but if you want add 12T and possibly 14T to the cassette, you have to take out 1-2 cogs in the middle. That's the issue, because many of the cassettes share the same middle, something along the lines of 21-24-28-(32/33/34). You need a 'new' middle cog with teeth that the original cassette didn't have.

So if you want to do something like 11-12-13-14... and don't want huge tooth gaps in the middle where you took out 2 middle cogs, you have to mix and match different cassette cogs.



Starting cassette: Shimano 11-51T 11-speed. Last 3 cogs are riveted together.
11-13-15-18-21-24-28-33-39-45-51



Mix the above with Shimano 12-32T 7-speed.
12-14-16-18-21-26-32

12 is in italics because you will need the correct speed for 12T; 7-speed 12T has a built-in spacer too wide for 11-speed. So you purchase that 12T separately for whatever speed you have beyond 7/8.

The key cogs here are 14, 26 and 32 (26 more important than 14 or 32).


New mixed cassette with 2mm spacers to match 11-speed cog spacing. Original cassette is A, 7-speed cassette is B, individually-bought cog is C.
You do 14 or 15T depending on how smooth you want that part of the cassette (21 to 18 to 15 to 13 is a jump of 3, 3, 2; 21 to 18 to 14 to 13 is 3, 4, 1 --- jumpier).

11-12-13-(14/15)-18-21-26-32-39-45-51
AB-C- A - - B/A - AB -AB -B -B -A -A -A




You can do this with any other starting 8, 9, 10, 11, 12-speed cassette, just make sure you have enough spacers that are the correct width. 7-8 speed needs spacers around 3.0mm, 9-10 speed close to 2.5mm, 11-12 speed around 2.0mm. Not exactly the width that the original spacers are but it will shift surprisingly well.

Let me put it this way: cogs from a quality, brand-name cassette that are taken apart like this and put back together with generic 2.0, 2.5, or 3.0 spacers still shift better than a cheaper off-brand cassette with the 'correct' spacers. Seriously. It's such a small difference that the rear derailleur will probably not even notice. Just remember for the first two cogs that they will need to match your shifter's speed, and the rest you can just use whatever spacers that approximate the spacing. You'll be fine.

 

[calab]

I would vote to sticky your post.

 

[richj8990]

Just found a distributor on E-Bay that has 11 all the way to 25T cogs in 8, 9, 10, 11, 12 speed. They are again about $6-8 each.
So you don't even need to buy a separate cog donor cassette.

I just bought 12 and 23T, take out 21 and 24T and then with new cogs in bold:
11-12-13-15-18-23-28-33-39-45-51
Not bad, a bit of a 3-5/5-3 jump at 15-18-23 but should be fine.

I'm also thinking of removing the odd-numbered small cogs when they wear out and replacing most with even cogs instead of trying to stack them in a row with one tooth spacing, just keep 2-tooth spacing at the top end and have it mostly even instead of odd. For example, if 11, 13, and 15 wear out or are really on the way compared with the larger cogs, then:

12-14-16-18-21-24-28-33-39-45-51 and you get to keep the original 18-21-24-28-33... as long as it's not too worn.

 

[PaPaSteve]

Spacer thickness is one dimension to consider but also be aware of cog thickness has changed between years and series.
Derailleur systems have some side to side tolerance built in but too much cog alterations may lead to shifting frustrations.

 

[calab]

12-13-15-18-23-28-33-39-45-51

I like that without the 11.

There is a crank system, that allowed for 4x cranks called Mountain Tamer, I dont need climbing gears myself but its an option.

Mountain Tamer Chainring Adapters, Gorilla Brake Beefers, Gorilla Headlocks and more

Mountain Tamer - Lower gears for your bike.

www.abundantadventures.com

 

[richj8990]

Spacer thickness is one dimension to consider but also be aware of cog thickness has changed between years and series.
Derailleur systems have some side to side tolerance built in to much cog alterations may lead to shifting frustrations.

So for Shimano it's almost exactly 1.0mm difference between 7/8 speed and 11 speed for the total sprocket + spacer thickness.

In way it's lucky that I'm using 7/8 speed cogs in the middle and smaller cog end, because 1.8mm sprocket width + 2.0mm spacer = 3.8mm which is almost exactly the total width for 11 speed. That would in theory also work for 10 speed, but 9-speed would need 2.5mm spacers. 9-speed cassettes are cheap anyway so no need to mix other speed cogs with those. Really only for 10/11/12 speed to mix and match the smaller ends from cheap cassettes.

Shifting is pretty good overall. I've done maybe a couple hundred miles on this setup and I didn't notice any issues. But for a mid-drive I'm doing 100% steel cogs now and will need to change some out soon, like the 11T...