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I am interested in getting a left-side power meter for my road bike. It has Shimano 105 components. I'm considering a 4iiii Precision left-side crank, in a 105 or Ultegra version.

I looked, and don't see the size of my current cranks marked anywhere. How do I measure them? Is the distance the total length of the crank, or the center-to-center distance from the bottom bracket to the pedal spindle?

Criggie
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Duncan C
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1 Answers1

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It's the center-center distance, but it should be stamped on the inside of the arm.

Adam Rice
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  • Adam, thanks for the reply. Will it be stamped on the inside of both arms, or just one? And where on the inside, exactly? I looked and didn't see it. (I have a Wahoo cadence sensor on the inside of the left arm. It's possible it's covering the stamp.) – Duncan C Jan 01 '22 at 02:19
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    Ah-ha! I went back and looked more closely and found it. It seems my cranks are 172.5 mm. Thank you! – Duncan C Jan 01 '22 at 02:25
  • For others' reference, here's another question that shows where the length is stamped. https://bicycles.stackexchange.com/questions/67619/what-power-meter-would-work-on-my-bike?rq=1 – Weiwen Ng Jan 02 '22 at 14:46
  • Thanks for the answer. I did eventually find the crank length info printed on the crank. – Duncan C May 07 '22 at 23:50