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Daily Archives: November 17, 2020

The Ultimate Hack for a Short B Screw on a Rear Derailleur…

So, the one problem I had with my wife’s gravel bike rebuild is that the medium cage Sora derailleur is on backorder. This is a massive problem for normal folk, but not for me. I’m only rarely normal folk. Or is that… regularly… Meh. I went out to the parts shed, pulled out the old 9 speed Ultegra derailleur out of my old Trek box, and installed that on her bike till the new one comes in. BAM! Drops mic.

One small problem… the B set screw that pulls the pulley wheels away from the cassette teeth. Even after adjusting it, with the B screw all the way in, the pulley teeth were crashing into the cassette on the smallest cog. Which is better than when I first set it up because it was crashing into the biggest and smallest cogs.

I set it so my wife couldn’t use the 32/11 and 47/11 combos and suggested she not use the 11 tooth till her new derailleur came in. Because how in God’s name do you fix that!

Early yesterday morning, I was surfing for B screw setting instructions before work, and I happened on a video that showed a hack to fix a short set screw. He recommended a m4 x 25-mm with a nut to rest on the derailleur hanger. They were relatively cheap, though, so rather than just go for a 24, I picked up a 6, 12, a 20 & a 25, and one nut.

The original is in the middle. The stainless screw was too small. The black 20 too big…

I only needed the m4 x 12. And I didn’t need the nut.

All 18 gears, works beautifully. And a total cost of $3.46. Gotta love it.