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  "path": "/2026/05/31/backyard-machinist.html",
  "publishedAt": "2026-06-01T01:40:11Z",
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  "textContent": "Okay, lemme get this out of the way first: these lovely mid-80s SR Sakae cranks were likely headed to the co-op if I couldn’t make this work. When I pulled them off the Olympian I discovered that they only really had usable 110 BCD drilling at the ends of each arm. Where one might expect to find 74 BCD holes inboard were instead a few shallow, unthreaded starter holes. I’m building up this bike for my wife and I want comfortable 2x gearing, so I want the ability to run something in the high 20s for an inner chainring like I use on my own bikes. So…I found out what size drill I needed to drill holes before using a bottoming tap to cut threads for chainring bolts. I was too impatient for proper work-holding, so I kind of, uh…I freehanded all 5 holes. Kids (and adults), don’t do this at home. This is where I know I was extremely lucky because this could have all gone horribly wrong. In reality, I ended up with 5 holes that are straight enough to securely attach a 74 BCD inner chainring without any weird stick-out of the bolt heads or difficulty tightening any of them! I did, of course, take many measurements. I used my micrometer to sort out how much depth of cut I needed for the thread past the chainring and I taped the drill bit as a stop marker. I still had at least a good 5 millimeters of buffer. Again though—take the time to sort out proper work holding, particularly if you’re trying this crack-pot idea on a part that you really care about (or is actually worth something). This is super niche, nerdy shit, but I left the shed this afternoon feeling like Tom Hanks in Cast Away after he built a fire. But he didn’t have a quarter cup of scattered aluminum swarf to clean off of his cluttered workbench.",
  "title": "Backyard Machinist",
  "updatedAt": "2026-06-01T01:40:22Z"
}