tomii/aarn: available now: tomii + 44rn 1x 130#44 road chainring [bicycle]
The idea for this chainring started so long ago that I can’t even remember when it was. Nao Tomii was having a hard time getting his machine shop, for the now retired 3RRR product line, to make some necessary changes to the tooth profile that he had been using for his track chainrings. He came to me with a sketch of this chainring that made hearts with the spider pattern of the crank arms. Originally it was a track ring (144BCD), then it was a track-style ring that fit onto a road crankset (130BCD), then finally it ended up as a one-by-n road ring (3/32”) in 130mm BCD and 44 teeth. This happened over a period of three or four years, we even made some prototypes in each style over the years.
There are a few elements of the design of this ring that I think are interesting...After Nao passed the rough sketch to me, I wanted to add some features that were consistent with the overall idea of the ring, so I incorporated the heart cut-out around one of the chainring bolts, and a variable radius blend on the inside of the heart shape to soften that feature. I also thought that it would look sharp if the teeth of the ring blended into the nameplate. I wanted to avoid having gunk build up at the seat where the teeth meet the ring body, so instead of putting a sharp corner there, the detail is milled out with a ball endmill.
Another unique aspect of this chainring is the application. A lot of people (myself included) have bicycles that run a single ring up front with a multi speed cassette in the back. The idea of making a tooth profile that is not designed for shifting, but is designed for tighter engagement with the chain when used with up to a ten speed cassette in the rear, was intriguing to me. I took some liberties with the design, and the prototype got good reviews during the field test. The ring will work with a chain catcher/keeper like the Paul Components version, and fits snugly on all of the cranks tested.
These chainrings are a little more expensive to make than the track ring that I have previously released, just because of how much machining is required to make each, so the price reflects that increase. Manufactured in Peabody, Massachusetts, USA, from certified 6061-T6 aluminum plate stock. These chainrings are fully CNC machined. All edges (front and rear) are machine broken with a 45-degree 0.010-in deep chamfer. Product is packaged in brown paper with a QC certification label and number, and shipped USPS Priority Mail.
The price is $88 + S&H, there are 50 rings total available (26 Black and 24 Clear/Silver). Get it here.