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Prevent brain freeze on your next sub-freezing adventure with the Castelli WS Skully Cap.

  • Windstopper X-Lite Plus front panel for warmth and comfort
  • Easily fits under helmets and extends over ears
  • Fleece upper wicks moisture and retains heat
  • Extended back for extra coverage
  • Reviews
  • Q & A

What do you think about this product?

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Clutch Cap

  • Familiarity:I've put it through the wringer

One of my absolute faves. I have crushed miles in this skully at 10 below zero, it fits quite nicely over the Seamless Balaclava and under my helmet. I forgot this piece one freezing day and was truly missing it. It is not one to wear into the 50s unless you want to fry an egg on your dome.

Clutch Cap


  • Familiarity:I've used it once or twice and have initial impressions
  • Fit:True to size

I bought this after a windstopper head band from Craft just didn't do the trick on a 2hour 35-40 degree ride. The first time I used it was actually as a snowboarding helmet liner. The rear "flaps" seem a bit much, but they really aren't intrusive even when riding with your head twisted sideways for a majority of the day. I wore this on a bike ride in similar temperatures and it did great. Low bulk, super warm. Did I sweat? I did sweat when snowboarding, a little less riding. The biggest choice here is full protection or something less like a head band, in the end I went full protection and I don't regret it. The flaps aren't going to make you considerably warmer than just a cap. I echo other sentiments that this is probably comfy to mid 40's... then again so are probably 8 of 10 of the other caps.

Snowboarding was done at 15-25 degrees and it kept me warm even then.

Oh, I have a HUGE head, and this fit just fine. I tried on a Giordana one size product prior to this and it was tight around the ears. The fact that you have excess coverage here does not necessitate a seam right where you ear would be which could pinch you.

Excellent, Comfortable up to mid-40's

  • Familiarity:I've put it through the wringer

Typical excellent Castelli quality. Used it many times from mid-20's with 20mph winds to low-50's. I would personally only use this up to mid-40's. It tends to be too warm after that, especially if the sun is up. It fit me well, but fair warning, I do have a Large head (wear Large in Bell and Giro helmet sizing). I like the look, the cut, and how the ear-flaps taper down to the tail at the back of the neck. I don't have to do the stretch/pull that I normally do with my other skull caps that do not have this long tail.

good for sub-45 rides

  • Familiarity:I've used it several times

This will be good for sub-45 degree rides but anything much more than that will leave you sweaty. I have a large-circumference head (59cm) and finding headgear that isn't overly tight can be a challenge sometimes. This is a good fit, extra wind protection over forehead and around the ears, the tail over the back of the neck seems a little over-engineered but it doesn't get in the way.

Great additional warmth

  • Familiarity:I've used it several times

I have a fairly big head (both physically, this cap fits well, and otherwise, just ask my wife). This cap is snug on my head, and fits well under my helmet. Strangely, it reduces wind noise around my ears, making it actually easier to hear overtaking cars. The effective range for me seems to top out at about 45F. I've worn it down to about 30F, and have not wished for any more warmth.


  • Familiarity:I've used it several times

I've had a great experience with this cap as an additional layer when it gets into the 20s. I use it with the Castelli Viva Thermo Skully Cap underneath. I agree with Darrel's review that it is a little on the loose side. That works fine for me since I use it as a second layer, but I'd be cautious on the sizing if I were looking to use this as a single layer.


  • Familiarity:I've used it several times

Have had a few brisk morning rides already with this cap. I have a big head and it fits me great. It is also pretty thin which makes it fit nicely under my helmet. Totally windproof it actually get a bit warm going uphill but I suppose that is the point.