aarn: available now: 144#47 track chainring [bicycle]
This is my first self-branded product. Before I get into the details, these are available in black and clear anodized finish for $67 in my online store. Store is located here, here, and here. Quantities are extremely limited. I had 50 total made; 30 in black and 20 in clear. Other than the anodizing treatment, all of these bicycle chainrings are identical. The bolt circle diameter is 144-mm, and each has 47 teeth. Chainrings are designed for ⅛-in track/bmx chain.
Let’s get into the details - I had been searching for the right machine shop to make these chainrings for about eight months. Finally I decided on a two-man shop in Peabody, Massachusetts, USA. I am very glad that I waited, because I have not seen CNC machining of this caliber in a long time.
The attention to detail that the machinists paid when crafting these can be seen in the quality of the end product. The rings were fully CNC machined from certified 6061-T6 aircraft grade aluminum plate stock, then lightly buffed and delivered to another local shop for black and clear hardcoat anodizing.
At no point in the process of making these chainrings did a file or manual deburring instrument touch the parts, every single edge on the chainring (front and back) has a precision machine-broken 45-degree 0.010-in deep chamfer. A custom 20-degree chamfer tool was used to precisely bevel each tooth during the machining process. In addition to the quality of the machining and finishing, each part was labeled and inspected before it left the shop. The black anodize is as black as it gets, and the clear anodize is crisp and clean.
Prior to selecting a machine shop, I machined prototype blanks (chainrings with no aesthetic features) with the new tooth profile that I had been developing. I gave these hand-numbered blanks to friends and had them roadtest the fit, noise-level, and wear of the tooth profile. Noise-level might seem like a strange parameter on which to conduct performance tests, but I was trying to get the widest quiet-running tooth possible. Wide BMX-style teeth grind and grate until they are broken in and I wanted these chainrings to be smooth and quiet from day one. I also went through a dozen or so designs before settling on the the cut-out design and labeling scheme.
After I had selected a machine shop, I cleared out my Roth IRA…I mean Apple stock…I mean piggy bank to finance these chainrings out of my own pocket. To keep costs low I have marked up these chainrings $17 each, and am offering them to the public directly. MSRP on these chainrings would be more than $100 if I tried to distribute them to retailers because of how much I paid to have them manufactured. Most chainrings coming from China cost about $10 to make (I know, I sent out some requests to shops in China to see what was up), mark-ups from distributors and retail shops comprise the rest of the sticker price. I am trying to provide a limited-edition, high-quality, locally-made product at an affordable price point. Each part is packaged in brown paper with a “QC Pass” inspection stamp, and numbered (x/20 or x/30 depending on finish color).
Get ‘em while they last here.
Media can be found here.
I’ll be putting some shot up of these on a bike very shortly, I just got them in on Friday and wanted to get them live.
Prior art: aarn: boring 42th chainring v2 [bicycle], aarn: 42th prototype track chainring [bicycle]
[edit]
Rings on some whips:
(Party chainring photo by E. Baumann)
