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Castelli Thermoflex Knee Warmers

Item # CST00GO

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  • Black, S ($39.95)
  • Black, M ($39.95)
  • Black, L ($39.95)
  • Black, XL ($39.95)
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Item # CST00GO


Happy knees, good ride.

The small tendons, ligaments, and muscles around your knees play an integral role in your ride quality, so don't leave them cold and exposed when you're riding in unpredictable shoulder season weather. A light breeze in your driveway turns brisk in a hurry when you drop into a long descent, so cover your 'caps with the Castelli Thermoflex Knee Warmers to help ward off stiffness after hours on the roads. These stretchy fleece warmers insulate but remain breathable when you break a sweat, making them ideal for the changing temps during spring and fall.

  • Protect your knees in cool weather without overheating
  • Form-fitting cut with gripper elastic prevents slippage
  • Thermoflex fleece wicks moisture while it insulates
  • Cross-wrap cuff at the bottom for a comfortable fit

Tech Specs

Thermoflex fleece
Claimed Weight:
[pair] 94g
Recommended Use:
Manufacturer Warranty:
1 year

Size Chart


Arm & Knee Warmers
Rider Weight

99.2 - 132.3lb

(45 - 60kg)

132.3 - 154.3lb

(60 - 70kg)

154.3 - 176.4lb

(70 - 80kg)



Short Size XS - M S - M L - XL 2XL - 3XL
Short Size:
Take your typical cycling short or bib sizing for comparison.

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Multi Usage

  • Familiarity: I've used it several times
  • Fit: True to size
  • Size Bought: Large

When temps rise above 50 or so and exertions are a bit stiffer I reach for knee warmers for protection. This newest version of the Thermoflex warmer family uses a very soft and smooth material that is not as stiff as Nano Flex, but lacks the water resistance. The cross-wrap cuff is a nice feature, although I have to check that they do not fold up during rides as it is a very thin cuff. Overall fit is true to size, bought a large for my 34 inseam and are long enough for my legs, don't ride up or slip down with the upper silicone leg gripper either.

Perfect for when its warm-ish

  • Familiarity: I've used it several times
  • Fit: True to size
  • Size Bought: Small

Knee warmers are seemingly arbitrary, which I have thought for many years. Why not just wear full legs? Why not wear just shorts? But after living through a spring in Utah, these bad boys are a necessity for when you start a ride at 7am and its snowing but the forecast later shows sunny and 65. Riding in the mountains is always a mystery when getting dressed.

On a technical note: these do a great job of staying up on my leg, they are long enough to cover the necessary areas on my long legs and have great silicone grippers that grip both sides so it stays on my leg and my bib shorts. I am 5'11'' and 148lbs, long legs and skinny and I have a small.