Bike Forums - View Single Post - Does anyone have experience with Stone oval 1x chainrings?
Old 03-06-18, 09:17 PM
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Originally Posted by tFUnK View Post
Never tried to change my rings but from what I gather on the internet the Red Exogram cranks should take any other ring.
Thanks tFUnK,

Unfortunately, the SRAM Red Exogram is identical to mine in that it has the hidden fifth chainring bolt behind the crank arm. So, no, it will not take "any other ring".

The criteria for the SRAM chainrings made for these cranks appears to be:

1 - They are 4 mm thick at the mounting surface so they fit between the rear mounting face behind the crank arm and the four front mounting faces on the exposed spider arms.
2 - For 2x systems, the outer chainring includes a pin to close the gap between it and the crank arm to prevent a chain from slipping between and getting stuck.
3 - For 2x systems, the teeth of the outer chainring are biased slightly toward the outside (away from the frame). For 1x systems, the teeth are biased slightly toward the inside (toward the frame).

In my experience, the requirements for 1x are the 4 mm thickness at the mounting holes and the teeth being biased about 2 mm toward the frame.

Since my original post, I've found another off-the-shelf oval chainring for 1x systems with a 5-spoke 110 BCD crank: the Rotor QRings QX1. Here's an example. It's only available up to 52t and, at US$119, it costs about double what the Stone chainring in my original post costs. Rotor says it's compatible with clutch-type rear derailleurs which sounds like it will work with SRAM. But they do not comment on the SRAM Red cranks with the hidden bolt. Positives include: It appears much stronger, more aerodynamic, offers a more oval shape than the models from Stone Design, and comes from a reputable company. Negatives include: It is heavier, available only up to 52t, and costs twice as much.

Back to my original post, I hope someone will notice this thread who actually has an oval 1x chainring from Stone Design for a 110 BCD 5-spoke crank. You'll sometimes see them advertised as being made by Deckas but they always seem to have the name "STONE" on them. They are available in a very wide range of sizes up to 60t in 2t steps. They even come in a variety of colors---but only black appears to be available outside of China.

Kind regards, RoadLight
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