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Styled for maximum airflow and go-fast good looks, the lightweight, 21-vent Circuit was designed using Computational Fluid Dynamics, for an air-gobbling shape that delivers superb ventilation and unbeatable air flow.

Circuit

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Features

  • Lightweight road helmet for superior performance
  • 21 CFD software enhanced vents for maximum airflow and efficiency
  • Premium, wicking fit pads
  • One-hand adjustable ZipTite fit system
  • Three sizes ensure the best fit
  • In-molded strap retention system with Lockdown strap adjusters
Part No. Certification Color Size Weight
420670 CE, CPSC Adult Matte Black Elite S 20 1/2 - 22 1/8, 52 - 56cm 280g
420671 CE, CPSC Adult Matte Black Elite M 22 1/8 - 23 1/2, 56 - 60cm 300g
420672 CE, CPSC Adult Matte Black Elite L 23 1/2 - 25, 60 - 64cm 320g
420676 CE, CPSC Adult White / Silver Elite S 20 1/2 - 22 1/8, 52 - 56cm 280g
420677 CE, CPSC Adult White / Silver Elite L 23 1/2 - 25, 60 - 64cm 320g
420682 CE, CPSC Adult White / Silver Elite M 22 1/8 - 23 1/2, 56 - 60cm 300g
430266 CE, CPSC Adult Black / White / Red Elite S 20 1/2 - 22 1/8, 52 - 56cm 280g
430267 CE, CPSC Adult Black / White / Red Elite M 22 1/8 - 23 1/2, 56 - 60cm 300g
430268 CE, CPSC Adult Black / White / Red Elite L 23 1/2 - 25, 60 - 64cm 320g
Circuit

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Pro Sizing

Measure the circumference of your head using a cloth tape measure or a piece of string and a ruler. Use the chart below to find the proper helmet size based on your measurement.

cm 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66
  Small                  
          Medium            
                  Large    
                      X-Large

1 Head

Take your measurement horizontally across your brow and over your ears.

Circuit

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Ride it and love it. If not, we’ll take it back.

Ride it and love it. If not, we’ll take it back.

It’s that simple.

If for any reason you’re not satisfied with your Bontrager products, return the item - along with the original sales receipt - to the place of purchase within 30 days of purchase date for exchange or store credit.