Pairing Rotor crankset with Shimano 12-spd groupset

[cyan]

Attempting to get a Rotor ALDHU crankset (with Rotor round rings updated for 12-spd) to go with the rest of Shimano 12-spd Dura Ace groupset. How well will the shifting work vs. the full Shimano setup, as the chainline will be off by 0.5-1mm as per Shimano specs.

Also, Rotor has 30mm spindle vs. 24mm on Shimano, and I wonder if 30mm is better or worse there. It seems to me the only negative is smaller bottom bracket bearings for 30mm and potentially shorter bearing life?

Anyone has first hand experiences with these components?

[Kyle h]

I ran non Shimano rings, granted they were CarbonTi not Rotor, on a SRAM Dub crankset and spider without issue for 2-3000mi. I added a 2mm spacer to the driver side to achieve the chain line I needed without maxing out the indexing in the FD. Shifting was 90% as good as Shimano rings I would say, and I can’t say there was a particular event where I would go “man, if only I’d had Shimano rings!” while using them. Honestly the only place you could probably even notice is with a front derailleur shift to the large ring, a setup with Shimano rings is ridiculously fast, like almost instant, and smooth, with the non-Shimano rings it was like a slight hesitation but always shifted fine. IMO one of the biggest changes for 12spd di2 vs 11spd was the front shifting improvements and I would say my 12spd setup seemed to be on par with 11spd while using the CT rings, but I did end up swapping back to a Shimano setup recently for a number of reasons, shift quality was a minor one.

[Mark McM]

I've used Rotor Aldhu cranks, but on a Campagnolo 11spd system. But I can add a few words about the Aldhu cranks:

Aldhu cranks are available with either aluminum or carbon crankarms. There are both 24mm and 30mm spindle versions of the aluminum crankarms, and the carbon crankarms are 30mm spindle only. The 24mm spindle fits HollowTech II (Shimano) bottom brackets. Both the 24mm and 30mm spindle versions use a bearing preload adjuster with a few millimeters of adjustment, so you should be able to adjust the chainline by +/- 1mm with spacers.

[fredd]

Having used Rotor rings with Campy 11s, I can say the shifting was significantly worse than Campy or Shimano rings.

What's even more cursed is that the rotor 110-4 spider I had had the same bolt spacing as shimano, but had little tabs that made them incompatible with Shimano rings. Which is just bad.

[Mark McM]

Oh, I forgot to mention: The Rotor Aldhu system also has a Shimano compatible spider available, so you can use your original Shimano chainrings.

[nmrt]

Funny that you ask because I am in the midst of doing the exact same thing. 12-speed Shimano with Rotor Aldhu carbon crankset with Rotor oval (12-speed) chainrings. I never thought it would not work.

I do have experience with using Rotor Aldhu carbon crankset with Rotor oval chainrings and Sram Red 11-speed drivetrain. Works okay enough for me.

[RollingCole]

I've installed multiple cranksets for others with the Rotor DM round rings on Ultegra and DA 12-speed systems, as well as 11-speed Shimano and SRAM setups, electronic and mechanical. Shifting was problem-free across all systems. I haven't had any issues shift speed or chain drops on my personal bikes either. Shift quality felt very close if not the same as Shimano rings. Some cranksets were Shimano swapped to Rotor so I got a chance to A/B them pre and post install.

Regarding any 0.5-1mm difference, I was able to properly adjust the limits of the front derailleur as Shimano specifies, although trim adjustments for big-big were at the max of their adjustability. For these cranksets, Rotor usually sends some micro-spacers with the crank axle to adjust the chainline slightly.

I've used the 24 and 30mm spindles from Rotor, and I can't say I ever really formed much of a preference. I enjoyed my 24mm Vegast crank setup because I got to use a DA bottom bracket, but that's about it. The other crank I used was a 30mm INPower and it also performed well. Installed it on multiple bikes with a variety of bottom brackets and just knew I was working with BB30 bearings in the end, which I didn't mind.

[skouri1]

bumping this up. SRY. for those of you with experience installing these cranks, can someone point me towards a spacer chart that is updated?
I have an external T47 with a shimano BB that needs 0 spacers with the 8100 hollowtech crankset.

Do I need two 1mm 24mm axle spacers (one on each side?) or is it a straight swap?

Also, do you need a torque wrench to get this guy to 40? Or just tighten it as much as possible. I am not sure if it is a cassette lockring situation or if precision is needed...I dont have a torque wrench that goes as high as the *35-40NM it needs.

[Mark McM]

Here's the latest Rotor spacer chart for Aldu 24mm, from the Rotor America Support web page:

https://cdn.shopify.com/s/files/1/23...f?v=1691000272

It appears to call for a 1mm spacer on each side.

Here's the Aldhu/Vegast crankset installation manual:

https://rotorbike.com/media/mageworx...dhu_vegast.pdf

The instructions call for each crank bolt to be tightened to 35 Nm, which is about 26 in/lb. It really is best to install with a torque wrench.

[skouri1]

Thanks. Is there a forum rec for a torque wrench beyond the small bolt 12-15nm range ? I figure there must be good value non bike specific wrenches. Also I'm guessing 3/8" ?

[cgolvin]

I cheaped out and bought a Harbor Freight torque wrench for the higher values. While I don't have high confidence in its precision, it has worked well for me. That's not a recommendation, I think it's likely better to spend the money for a quality model.

[oldguy00]

Originally Posted by Mark McM

Here's the latest Rotor spacer chart for Aldu 24mm, from the Rotor America Support web page:

https://cdn.shopify.com/s/files/1/23...f?v=1691000272

It appears to call for a 1mm spacer on each side.

Here's the Aldhu/Vegast crankset installation manual:

https://rotorbike.com/media/mageworx...dhu_vegast.pdf

The instructions call for each crank bolt to be tightened to 35 Nm, which is about 26 in/lb. It really is best to install with a torque wrench.

Interesting, I didn't know about that chart, and was just going off a youtube video by rotor that simply stated that 'most' setups would not require the thin plastic spacers.
I bought a Rotor Aldhu P2M crankset, put my dura ace chainrings on it, installed perfectly into my BBinfinite BSA BB with no spacers. Shifting seems to be working perfect.

[skouri1]

did your previous shimano crankset require spacers?
I would love if it didnt need them just because I dont want to push out Q factor anymore than necessary.

[oldguy00]

Originally Posted by skouri1

did your previous shimano crankset require spacers?
I would love if it didnt need them just because I dont want to push out Q factor anymore than necessary.

They did not. Previous cranks were 9100 and 9200 Dura Ace. Installed on a Felt IA FRD with threaded bottom bracket. I used a regular dura ace bottom bracket, and more recently a BBInfinite Ceramic BB.
My Rotor cranks did come with the plastic spacers, so no big deal if I needed them, but it appears I don't. I -did- leave the rubber o-rings on as per the cranks instructions.

[Mark McM]

Originally Posted by skouri1

did your previous shimano crankset require spacers?
I would love if it didnt need them just because I dont want to push out Q factor anymore than necessary.

On Rotor cranks, the spacers have no effect on Q factor. The Q factor can only be varied by changing spindle length (there 2 different length spindles available for Aldhu cranks). The spacers only take up extra space on the spindle to allow the bearing preload to be set properly. With a given spindle length, the Q factor will be the same regardless of the width of the BB.

One feature of using spacers to take up the extra spindle length is that if necessary, the spacers can be swapped between right and left to adjust the chainline.