The new Crux: can it handle a 52/36?

[Dr Luxurious]

Yes, I want a double. With road rings.

Will it clear?

Would settle for 50/34 if I had to

[catchourbreath]

Only compatible with grx x2, axs 50/37 max,

[Dr Luxurious]

thx!

[ikecycke]

It's not 'officially' compatible per Specialized, but you can run a regular-spaced 50/34. I can't remember if it was a thread in General or in Production Bikes, but there was a guy running full Ultegra with a 50/34. I plan on doing the same to my Crux after CX season is over. Pretty certain the 52/36 is a no-go, though.

[Gsinill]

Originally Posted by ikecycke

It's not 'officially' compatible per Specialized, but you can run a regular-spaced 50/34. I can't remember if it was a thread in General or in Production Bikes, but there was a guy running full Ultegra with a 50/34. I plan on doing the same to my Crux after CX season is over. Pretty certain the 52/36 is a no-go, though.

I do (DI2 12) with 11-34 in the back on my '23. Works perfectly.

[Philster]

I think the compatibility list is due partly to tire clearance (i.e. you might loose some with the 50/34). Rotor makes a wider “gravel” spindle. I wonder if this would buy you clearance for larger rings.

There are folks on weight weenies who have tried different things.

[efuentes]

Here are lots of info ...

https://weightweenies.starbike.com/f...5aef708a9622f8

[sheepbleat]

I am currently running a Crux with Shimano 50/34T. It's not ideal. I don't think it's possible to run 52/36T safely.

Using a Shimano 50/34T setup requires a spacer between the drive-side bottom bracket cup and frame. This spacer will move your drive-side crankset (and subsequently your chainrings and chainline) outward, away from the drive-side chainstay.

I initially tried a 1.8mm spacer and the chainrings rubbed a bit of paint off the chainstay during a hard race effort. I am now running a 2.1mm spacer. A road FD (FD-R8150 in my case) is still able to reach these chainrings with some adjustment. The bike shifts very well.

Use of the spacer means that the non-drive-side crank arm has less of the Hollowtech II spindle to grab onto. The plastic tab on the NDS crank arm isn't able to be pressed into the hole on the spindle.

I've yet to have a crank arm or spindle failure under sprint efforts and I'm sure it's fine, but I'd imagine that Shimano would tell me that I've voided the warranty.

Edit: Specialized publishes its chainring compatibilities for the Crux here.

[benb]

It would be cool if they made some kind of BB/Crank setup that would let you do this for people who don't care if the Q-factor got wider.

I could make this thing work just fine, on a road bike with a narrow BB I use the longer spindle shimano pedals.. take a bike like the crux, make the BB/Crank wider to get clearance for rings, and then just use the short spindle pedals...

For this kind of bike I would want the 50/34 or 52/36 personally I think.

[.RJ]

Originally Posted by benb

It would be cool if they made some kind of BB/Crank setup that would let you do this for people who don't care if the Q-factor got wider.

Yeah, the new GRX does this.

[Mark McM]

Originally Posted by Philster

Rotor makes a wider “gravel” spindle. I wonder if this would buy you clearance for larger rings.

This is probably the option that is most likely to work. There are other "wide" crank options (such as SRAM AXS Wide and Shimano GRX), but these often use smaller chainrings. But the Rotor system has interchangeable spiders, so larger chainrings can be installed. But the caveat here is that in order for clearance for larger chainrings, the chainline may need to be offset outboard. Rotor cranks use spindle spacers for adjusting the chainline, and in a BSA BB, the chainline of a double crank using the wide spindle the chainline can be adjusted out to around 50mm. (And of course, all the caveats around offsetting the crank chainline and its effect on shifting and drivetrain performance apply.)

[tonytourist]

I've had zero issues with my Crux running a 50/34 for the last 2.5 years. The difference is I use a Quarq PM so maybe that gives a little extra clearance compared to the Shimano cranksets.

[fa63]

If you don't mind running SRAM, their 48/35 chainring - 10/33 cassette combo is analogous to a Shimano 52/36 - 11/34 combo.

[jm714]

I picked up a Campagnolo Chorus 12 speed groupset last year from bike24 because it came with 48/32 crankset option that I’m realing enjoying right now. Maybe that would work for you.