# From 11-42 to 10-42



## Ananda (29 Oct 2019)

Gentlemen,
Lets assume we have a gravel bike wearing a 1x11 grx groupset and an 11-42 cassette, eg the cube nuroad sl or cube cross race sl.
Would it be a straight swap if we fit a sram 10-42 cassette (plus the appropriate wheel/hub body) or do we need to change the derailer and shifter too to sram components? The grx derailer is meant to take a min high gear of 11t according to specs, but is this carved in stone, that is the question.

And a second question....as I am interested in the above two bikes, does anybody know how big they can go on the chainring? Stock is 40t and I am wondering if there is space for 42t - 46t

Cheers!


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## Yellow Saddle (29 Oct 2019)

Standard freehub bodies can only handle down to a 11-tooth small ring. The 10-tooth rings fit onto special freehub bodies. I forgot what the proprietary name for those bodies are but I'm sure it is something gnarly like Eagle or Tiger or Turbo or something.

As for the chainring question, you can go as big as you can find, since in a 1-by drivetrain there is no front derailer that limits the size and configuration. 

What problem are you trying to solve?


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## Ananda (29 Oct 2019)

Yellow Saddle said:


> Standard freehub bodies can only handle down to a 11-tooth small ring. The 10-tooth rings fit onto special freehub bodies. I forgot what the proprietary name for those bodies are but I'm sure it is something gnarly like Eagle or Tiger or Turbo or something.
> 
> As for the chainring question, you can go as big as you can find, since in a 1-by drivetrain there is no front derailer that limits the size and configuration.
> 
> What problem are you trying to solve?



I am aware that a 10t requires a different freehub but that is not an issue since I plan to have two sets of wheels.
My problem is that 11-42 does not cut it, not enough range for me, but I can live with something like 42f with a 10-42 cassette.
My concerns for the chainring size is the shape of the chainstay. The fact it does not have a front derailer is not enough of a guarantee.


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## Ananda (29 Oct 2019)

According to this:

"*1x gearing:* TheRX-812 rear derailleur (RX-817 for Di2) is specifically for 1x and can handle up to 42T for the biggest cog. You can run Shimano 11-42 cassettes, or 11-40 for those who want a bit tighter range . You can even run a SRAM 10-42 cassette. That is not endorsed by Shimano but it works flawlessly in our lab and outside."

from here:
https://blog.3t.bike/2019/09/11421/gravel-tech-shimano-grx/

It seems that my question is answered.


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## Racing roadkill (29 Oct 2019)

Ananda said:


> According to this:
> 
> "*1x gearing:* TheRX-812 rear derailleur (RX-817 for Di2) is specifically for 1x and can handle up to 42T for the biggest cog. You can run Shimano 11-42 cassettes, or 11-40 for those who want a bit tighter range . You can even run a SRAM 10-42 cassette. That is not endorsed by Shimano but it works flawlessly in our lab and outside."
> 
> ...


Quite right.


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## fossyant (29 Oct 2019)

Needs to be an SRAM XD freehub I'm afraid, or the new Micro spline from Shimano. 

Yes it will run a 10-42 SRAM cassette, but that needs a SRAM XD freehub.

10t wont fit on Standard Shimano/SRAM 11 speed cassette freehubs.


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## fossyant (29 Oct 2019)

Ananda said:


> According to this:
> 
> "*1x gearing:* TheRX-812 rear derailleur (RX-817 for Di2) is specifically for 1x and can handle up to 42T for the biggest cog. You can run Shimano 11-42 cassettes, or 11-40 for those who want a bit tighter range . You can even run a SRAM 10-42 cassette. That is not endorsed by Shimano but it works flawlessly in our lab and outside."
> 
> ...



See post above - they didn't explain properly on the blog.


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## fossyant (29 Oct 2019)

Yellow Saddle said:


> Standard freehub bodies can only handle down to a 11-tooth small ring. The 10-tooth rings fit onto special freehub bodies.



I see you were ignored, but CORRECT !


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## Racing roadkill (29 Oct 2019)

Didn’t the OP say they are having two wheel sets, so the freehub issue, isn’t an issue? So the question was more about the mechs. Not the freehub.


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## fossyant (29 Oct 2019)

Racing roadkill said:


> Didn’t the OP say they are having two wheel sets, so the freehub issue, isn’t an issue? So the question was more about the mechs. Not the freehub.



It's as clear as mud what OP said. Can have two sets, but they would most likely have a little indexing to do between two different makes (a couple of turns on the indexing !


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## Ananda (30 Oct 2019)

Thanks a lot guys!


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