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Discussion Starter · #1 ·
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 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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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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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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Discussion Starter · #6 ·
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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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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