Castelli Insider Jersey review

A super lightweight jersey for the steamiest of indoor sessions that can also be used outdoors on hot days

Castelli insider jersey
Cycling Weekly Verdict

The Castelli Insider Jersey is highly breathable and, although intended for indoor training, can also function as an ultra-lightweight jersey for hot summer rides. If it weren't for the silicone gripper in the hem, which is disproportionately tight, this would otherwise be perfectly fitting jersey that performs well in its intended scenario.

Reasons to buy
  • +

    Super breathable

  • +

    Two rear pockets

  • +

    Doubles as a summer jersey

Reasons to avoid
  • -

    Disproportionately tight around the waist

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The Castelli Insider Jersey is the lightest jersey the Italian brand has ever made, and it certainly feels that way – there really is nothing to it. Designed for indoor training when modesty requires a top, it should also make a pretty handy hot-weather jersey come a summer heatwave.

Castelli Insider Jersey: construction

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Stefan Abram
Tech features editor

After winning the 2019 National Single-Speed Cross-Country Mountain Biking Championships and claiming the plushie unicorn (true story), Stefan swapped the flat-bars for drop-bars and has never looked back. 

Since then, he’s earnt his 2ⁿᵈ cat racing licence in his first season racing as a third, completed the South Downs Double in under 20 hours and Everested in under 12.

But his favourite rides are multiday bikepacking trips, with all the huge amount of cycling tech and long days spent exploring new roads and trails - as well as histories and cultures. Most recently, he’s spent two weeks riding from Budapest into the mountains of Slovakia

Height: 177cm

Weight: 67–69kg