# 50/39 Chainrings?



## Local Hero

I want to replace the big chainring on my Red Grouppo with a 50 tooth. I have an 11-28 cassette and I rarely use 52X11. I'm OK with the 39T small chainring. 


The Question:

*Is the 50T compatible with the standard cranks and 39T chainring?* 



Now to my next question:
I assume the weight difference between the 34T Red and 34T Force chainrings is negligible. If I do swap out the big ring, can I use a 34T Force ring? (I'll keep the Red cranks and Red 50T)


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## asad137

EDIT: I'm dumb!

Asad


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## lalahsghost

asad137 said:


> 50T chainrings will not fit on a standard (130mm BCD) crank -- there simply isn't enough room for the teeth _and_ the bolts.
> 
> Asad


How is that true when SRAM makes a 130 bcd 38/46t cyclocross crank (The S300)?

Local - if you find a 130 bcd Chainring for a 50t, and add it to your current setup, don't forget to readjust your FD a little, if any. P.S. I hear a 50/39t shifts like butter~


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## mendo

Most 50t chainrings are designed for the 110 bcd pattern. I'm sure there's an aftermarket ring somewhere that's a 50 with a 130 bcd. However, if I were you I'd look at a cassette that starts with a 12t cog. You'll have usable gears and have the added benefit of tightening up the ratios at some point in the cassette.


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## asad137

lalahsghost said:


> How is that true when SRAM makes a 130 bcd 38/46t cyclocross crank (The S300)?


Oh man I had a total brainfart -- you're absolutely right. It's a 38t or so that's the smallest that will fit on a 130mm bcd. Sorry about that.

Asad


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## Local Hero

Thanks for the replies, guys.


mendo said:


> Most 50t chainrings are designed for the 110 bcd pattern. I'm sure there's an aftermarket ring somewhere that's a 50 with a 130 bcd. However, if I were you I'd look at a cassette that starts with a 12t cog. You'll have usable gears and have the added benefit of tightening up the ratios at some point in the cassette.


I'm a bit frugal. I'm trying to do this cheaply if possible. A SRAM Red cassette costs three or four times as much as a single chainring. A new cassette would be more than halfway to a compact crankset. That said, you've got my wheels turning. Going from 11 to 12 in the rear is >9% change. While switching from 52 to 50 is <4%. 

I'd like to stay away from an after market ring. 

Hmm. 

I might just get the compact crankset and unload the full size.


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## skaruda_23

Local Hero said:


> Thanks for the replies, guys.
> 
> I'm a bit frugal. I'm trying to do this cheaply if possible. A SRAM Red cassette costs three or four times as much as a single chainring. A new cassette would be more than halfway to a compact crankset. That said, you've got my wheels turning. Going from 11 to 12 in the rear is >9% change. While switching from 52 to 50 is <4%.
> 
> I'd like to stay away from an after market ring.
> 
> Hmm.
> 
> I might just get the compact crankset and unload the full size.


Don't get a Red cassette then. I guarantee that you won't notice the difference. Try a PG-1070. 60 bucks on ebay, available in all kinds of ratios, shifts well/quiet too!


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## Local Hero

Thanks again everyone. 

As far as I can tell, there is no 50T 130mm SRAM Red chainring. 



FSA Pro and Dura Ace appear to be my only reasonable alternatives. 

Is DA worth spending three times as much? 

Any thoughts on compatibility?


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