Rotor 24mm axle on 30mm cranks

[cissepauwels]

hi, i got a question.
is it possible to have a 24mm rotor axle(BB86) and using the aldhu 30mm cranks?
i thaught of something with shims like a shim that slides intho the groves in the crank and over the groves of the axle.
so a shim or spacer that is 6mm thick. has a female and male side if you know what i mean.
a bit like this sketch

[cissepauwels]

this is a better sketch

[Vincentsmoox]

I never see that shim but maybe there’s a reliable reason for why they doesn’t exist


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[jch3n]

This is one of my biggest annoyances with Rotor. Like why can't they find a way to use the same arms for both 24mm and 30mm axles? I'm sure there are reasons, but it seems so counterintutive and detracts from the otherwise great modularity of their system.

Trying to devise some sort of shim/adapter seems like a bad idea. Just get Aldhu 24 arms or use a 30mm BB86 bottom bracket (it's not the most ideal, but it does work).

[Hexsense]

It's their short sighted design choice.
They do 30mm version first, with 2 length axle but both are 30mm diameter. There's no 24mm axle compatibility in mind. The big spline they choose make sense on drive side where the crank arm have to lock the chainring/spider in place as well. And they simply use the same on non drive side. This make sense, initially, as the DS and NDS crank arm would be (nearly?) identical and thus easier to produce and manage stock than using different size spline on each side.

Then they make 24mm axle later and realized that big spline doesn't fit through 24mm hole. They have to adopt a smaller size spline for 24mm NDS crank arm anyway.
If they went back in time, I think they'd use the 24mm version's nondrive side spline on 30mm version Aldhu as well.

[cissepauwels]

It's their short sighted design choice.
They do 30mm version first, with 2 length axle but both are 30mm diameter. There's no 24mm axle compatibility in mind. The big spline they choose make sense on drive side where the crank arm have to lock the chainring/spider in place as well. And they simply use the same on non drive side. This make sense, initially, as the DS and NDS crank arm would be (nearly?) identical and thus easier to produce and manage stock than using different size spline on each side.

Then they make 24mm axle later and realized that big spline doesn't fit through 24mm hole. They have to adopt a smaller size spline for 24mm NDS crank arm anyway.
If they went back in time, I think they'd use the 24mm version's nondrive side spline on 30mm version Aldhu as well.

yeah it is really stupid, atleast make a 24 and 30mm option on all cranks not like the aldhu carbons that are only in 30mm option

[cissepauwels]

This is one of my biggest annoyances with Rotor. Like why can't they find a way to use the same arms for both 24mm and 30mm axles? I'm sure there are reasons, but it seems so counterintutive and detracts from the otherwise great modularity of their system.

Trying to devise some sort of shim/adapter seems like a bad idea. Just get Aldhu 24 arms or use a 30mm BB86 bottom bracket (it's not the most ideal, but it does work).

yeah i wanted to use the aldhu carbons that are only in 30mm option.
the problem is , i want to keep the 24mm bb because if anything is wrong or something i can just put another crankset in it that i have laying arround

[jfranci3]

This is one of my biggest annoyances with Rotor. Like why can't they find a way to use the same arms for both 24mm and 30mm axles? I'm sure there are reasons, but it seems so counterintutive and detracts from the otherwise great modularity of their system.

Trying to devise some sort of shim/adapter seems like a bad idea. Just get Aldhu 24 arms or use a 30mm BB86 bottom bracket (it's not the most ideal, but it does work).

They don't mix. The 30mm axle is AL and the 24mm is steel. Rotor is using a tapered intference interface there and the materials have different needs. The AL is much softer than the steel and less forgiving. The splines need to be thicker on the AL.
They didn't make the AL axle 30mm for fun. They would have made it 24mm if they could. In order to be strong enough, the AL axle needed to be 30mm. It needs to be 30mm at that interface, not 24mm. On the NDS side, they cant fit a 30mm interface though the 24mm hole. On the DS side, they can make the same interface, which it looks like they do. Rotor doesn't want to make more part types than they have to either.

https://static.thcdn.com/images/large/w ... 296698.jpg
https://www.lordgun.com/content/product ... 22805.jpeg


Rotor 30 interface on arm
https://www.velo-perso.com/3207-thickbo ... -165mm.jpg

Rotor 24 DS
https://r2-bike.com/ROTOR-Crankarms-ALD ... -Road-Bike

[cissepauwels]

This is one of my biggest annoyances with Rotor. Like why can't they find a way to use the same arms for both 24mm and 30mm axles? I'm sure there are reasons, but it seems so counterintutive and detracts from the otherwise great modularity of their system.

Trying to devise some sort of shim/adapter seems like a bad idea. Just get Aldhu 24 arms or use a 30mm BB86 bottom bracket (it's not the most ideal, but it does work).

They don't mix. The 30mm axle is AL and the 24mm is steel. Rotor is using a tapered intference interface there and the materials have different needs. The AL is much softer than the steel and less forgiving. The splines need to be thicker on the AL.
They didn't make the AL axle 30mm for fun. They would have made it 24mm if they could. In order to be strong enough, the AL axle needed to be 30mm. It needs to be 30mm at that interface, not 24mm. On the NDS side, they cant fit a 30mm interface though the 24mm hole. On the DS side, they can make the same interface, which it looks like they do. Rotor doesn't want to make more part types than they have to either.

https://static.thcdn.com/images/large/w ... 296698.jpg
https://www.lordgun.com/content/product ... 22805.jpeg


Rotor 30 interface on arm
https://www.velo-perso.com/3207-thickbo ... -165mm.jpg

Rotor 24 DS
https://r2-bike.com/ROTOR-Crankarms-ALD ... -Road-Bike

yeah it is sad that they don't make a 24mm carbon cranks.

[Ferry]

+1 I would also like a 24mm carbon Rotor crank. Coincidentally, I emailed them a few weeks ago to ask wether they would produce a 24mm carbon crank in the future. I received no answer.

[WizzyBob]

If only it would work i'd save some money

I'm just in the process now of changing frames, I have the 30mm aldhu axle and cranks, my new frame uses bb86 and I really don't want to risk using 30mm in that, I don't want hassle with bearing life so I'm gonna bite the bullet and buy the 24mm version.

If anybody in the uk wants some 30mm 175 cranks with an offset axle give me a shout

[cissepauwels]

+1 I would also like a 24mm carbon Rotor crank. Coincidentally, I emailed them a few weeks ago to ask wether they would produce a 24mm carbon crank in the future. I received no answer.

yeah there chainrings are superb

hope they make those carbon cranks fast or i'm gonna make them myself lol