Technical FAQ: Tour de France timing transponders

  • By Lennard Zinn
  • Published Sep. 9, 2009
  • Updated Aug. 29, 2010 at 10:36 PM EDT

Question: While watching the Tour de France this year I noticed a piece of hardware on the riders’ bikes that I did not recognize attached to the non-drive-side rear chainstay. It was a red circular tab that hung down, usually two-thirds the way back toward the dropout. Several times a motorcycle cameraman would zoom in on the little device, but I never heard any explanation on what it was.


Dear Clay,

It’s a timing transponder


FILED UNDER: Bikes and Tech / Technical FAQ / Tour de France TAGS: / / / /

Lennard Zinn

Lennard Zinn

Our longtime technical writer joined VeloNews in 1987. He is also a framebuilder, a former U.S. National Team rider, and author of many bicycle books, including Zinn and the Art of Mountain Bike Maintenance and Zinn and the Art of Road Bike Maintenance, as well as Zinn and the Art of Triathlon Bikes and Zinn's Cycling Primer: Maintenance Tips and Skill Building for Cyclists. He holds a Bachelor’s degree in physics from Colorado College. Readers can send brief technical questions to Ask LZ.

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