RoadLight

Greetings,

I've been using a SRAM Red 22 crank in a 1x drivetrain with a 50t SRAM X-sync 1x chainring on a road bike for over a year (about 7,000 miles) and am very happy with it. With an 11-28t cassette, it matches the low rolling hills of my location very well. But I'd like to make a few tweaks.

First, I'd very much like to try an oval chainring to see if it will improve my power. Second, I'd like to try a 1x chainring with the wide/narrow teeth but without the clean-out bulge that SRAM includes on their 1x chainring teeth to clear debris from the chain during muddy cyclocross racing. (My bike stays on smooth paved roads and I believe the tooth bulge adds unnecessary friction. So I'd like wide/narrow teeth that are smooth.)

Until recently, I didn't think that anyone made a 50t oval chainring for 1x that would work with a five-spoke crank spider with a 110 BCD. And, since this is an experiment, I'd like to avoid an expensive custom chainring. So I'm considering a "Stone" model from China. It's available both on eBay and AliExpress. Here are the links to current listings: eBay • AliExpress.

I'm hoping that a member of this forum will be familiar with these chainrings and can answer some questions:

1 - Will the Stone oval 1x chainrings work with a SRAM Red 22 crank? These cranks have a hidden bolt behind the crank arm that inserts from the back side of the chainring. This requires the chainring to have a thickness at the mounting holes of 4.0 mm.

2 - Are the teeth of the Stone oval 1x chainrings offset toward the frame like other 1x chainrings (so the teeth of the chainring are aligned toward the centerline of the cassette)? If I remember correctly, the teeth on my SRAM X-sync 1x chainring are offset about 2 mm toward the frame to move them closer to the center of the cassette. (Note: This is about 3.5 to 4.0 mm inward of the tooth position of an outer 2x chainring.)

3 - Any experience with the durability and quality of these Stone oval 1x chainrings? They look kind of fragile to me.

Thanks in advance for your response.

Kind regards, RoadLight

squirtdad

Don't know about stone oval, but I used Bio-pace back in the day.......did not see any real power advantage, but did notice much smoother pedaling when i swapped them out for round chain rings.......

tFUnK

Never tried to change my rings but from what I gather on the internet the Red Exogram cranks should take any other ring.

RoadLight

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

RoadLight

Greetings again,

I received the following answer from the "China Cycling" channel on YouTube about the Stone oval 1x chainrings:

From the author's description, it sounds like the Stone oval 1x chainrings will not fit a SRAM Red 22 crank without modification and that modification may prevent you from being able to adjust the orientation of the oval. However, the author has trouble describing why this is so.

The last paragraph was also interesting. Evidently the original Stone oval 1x chainrings had teeth that were centered to the disc of the chainring. This means there were not optimized for a 1x chainline (and may not be optimized for 2x, either). In my experience with SRAM cranks, the teeth of an outer 2x chainring are biased toward the outside and the teeth of a 1x chainring are biased toward the inside. I don't know if this is true for all other manufacturers but the 1x situation should be fairly universal---a 1x chainring mounted to a standard crank will need to have teeth that are off-center toward the frame in order to properly center the teeth to the chainline of the center of the cassette. However, it doesn't need to be the exact center because some manufacturers (like SRAM) will locate the 1x chainring teeth 1-2 mm to the outside of the cassette center. This favors the smaller cogs a little. (Perhaps cross-chaining a small cog is more problematic than cross-chaining a large cog because the smaller cog has fewer teeth to hold the chain.)

While the last part stating "...their latest chainrings have an optimal offset..." sounds promising, none of the Stone's distributors that I could find discussed this issue. If you purchase one of these chainrings, you'll have not idea which version you'll receive.

I've contacted one of Rotor's distributors to obtain more information about Rotor's Aero QX1 chainring for 1x systems to see if it will fit a Red 22 crank. As I get more information I'll update this thread for the benefit of others who may follow a similar path.

Incidentally, the first professional use (that I'm aware of) of a 1x drivetrain with a large chainring for road use was Tony Martin's TT bike for the 2017 Tour de France (with a SRAM Red eTap system minus the front derailleur). But the sport that seems to be embracing this setup the most is Triathlon where a 1x is becoming more and more common for routes that are not mountainous.

Kind regards, RoadLight

Waschddl

Hi,

I am running the QX1 52T ring on my Quarq dzero 110BCD. Works fine. Before that I ran it on a SRAM Red exogram crank, also worked fine.
As i am looking to upgrade to a 54T ring, I also stumbled across the Stone rings. Sadly I didn't find and aero 110BCD 54T option from them for SRAM 5-bolt design, just for Shimano 4-bolt.

Best regards
Sebastian

fietsbob

how about Rotor Q rings instead? a quality product made in the EU.

Q ring with a professional racing user list..

Waschddl

We are talking 1x systems here... the regular Q-Rings are 2x and the QX1 Ring is already being discussed.

fietsbob

never seen them and no links were offered..