How do SRAM chainrings attach?

Discuss light weight issues concerning road bikes & parts.
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Valbrona
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by Valbrona

Not being a SRAM kind of person, I am wondering how the chainrings attach to a high-end SRAM crankset. Well, more accurately, what is the fixing arrangement in the case of the fixing-point hidden behind the crank arm?

I have a SRAM crankset travelling across the Atlantic and thought I would get a head start in trying to fit a pair of FSA Super Road rings to it. I know I will have to remove the chain catcher pin from the outer ring.

Thanks.

by Weenie


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prendrefeu
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by prendrefeu

The four exposed bolts are normal doubles.
The hidden is one extra long bolt with a spacer that goes between the two chainrings. I am not sure if it is the same length as the old "granny" bolt found on the "3 chainring" style cranks or if it is specifically spec'd by SRAM.

If the crankset is arriving with the SRAM chainrings already installed, use the same bolts for the installation of the chainrings of your choice.

Have fun out there!
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F45
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by F45

The SRAM oem chainrings are the same thickness at the bolt interface as "normal" 5 bolt rings, about 0.160", but the width of the area around the bolt at the hidden bolt is narrower. Take a dremel or end mill and shave down this area so your rings fit snugly in the hidden bolt area.

For the chain catcher pin, the oem diameter is 0.200" but any diameter near that size is fine. Buy some aluminum bar stock and a drill bit that are the same size, say 0.250". Drill the hole and sand down the new pin just enough to get it in there. Then smash it like a rivet, either in a press or a vice, until it gives an interference fit.

Praxis just came out with purpose made rings for this crankset so you could just buy those.

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prendrefeu
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by prendrefeu

...or just don't use a catcher pin, have your drivetrain set up properly, and save some weight. This is Weight Weenies.

And I disagree about the "take a dremel and shave it down" comment. The normal Praxis chainrings fit just fine, without any modifications, on SRAM Red cranksets. This has been discussed, at length, on this forum, and verified by Praxis. Praxis is releasing a "SRAM-specific" chainset because people out there don't know how to look with their own eyes at how something works and instead need someone to sell them a specific product for their "unique" situation. Hey, it's business.

Might want to read up, start here: viewtopic.php?f=3&t=103730&start=135#p916432
It goes on for a few more pages, including pictures when people just don't seem to get a how a circle works.
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F45
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by F45

Well, just a few days ago I fitted a Praxis cx ring set, 48 36, to fit on my Red 22 hidden bolt crankset. The end mill was necessary. Your insults are not.

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prendrefeu
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by prendrefeu

It wasn't personal, F45.
Really.

In that thread you'll see that people don't know how a circle works. You're not in that thread.
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by Weenie


Valbrona
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by Valbrona

Oops - I didn't see the mega 'Red Crankset' thread.

In summary: filing of outer chainring required only in the case of BB30/compact format, and then rotate both rings 180 degree for optimal alignment.

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