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While Castelli’s winter apparel uses its thermal Themoflex fabric, the Nanoflex Bib Shorts take warmth one step further with water-resistant, thermal Nanoflex fabric. This fabric is coated with nanofilaments to create a water-repellent, wind-blocking surface while retaining a soft, fleecy interior. If the weather is bitterly cold, we suggest the Castelli knee or leg warmers to cover your exposed skin.

To add to their comfort, the Nanoflex bibs incorporate breathable mesh straps and the Kiss 3 chamois. This insert is designed with a seamless microfiber to minimize chafing. The Kiss 3 also has variable density foam so that your body will be comfortable no matter how long you ride.

  • Nanoflex water-resistant fabric
  • Kiss 3 chamois
  • Reviews
  • Q & A

What do you think about this product?

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Keeps me warm, not sweaty

  • Familiarity:I've put it through the wringer
  • Fit:True to size
  • Size Bought: Medium

Perfect for the cooler days close to 40F. However they are not the best choice for long days in the saddle as they hold your man bits a little too tight. Material and stitching is great, however decals began to peel off within the first dozen uses.

I HATED them! Too painful to wear.

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

I got these on sale from the awesome folks at CC during the end of the year sales. In fact I bought quite a few pieces since the prices were so awesome. This unit however was a complete and total loss. I used it twice, both 30 mile rides, and by the end of the ride the chamois had worn a line on the inside of my leg near or I should say underneath my "bag of goods". I'm talking burning searing I can't go another mile kinda pain. The marks on my leg took 3-4 days to go away both times, which was really uncomfortable. The fabric was really cool. They seemed a bit long like the other reviews have indicated, but no big deal. They were reasonable warm for a bib short and the fit was true to size for Castelli! That means if you are an L-XL look at the 2XL. For me at first glance this seemed like a great bargain for the sale price of about $50. WRONG!! I threw $50 away! I won't wear them again. Strike that, I can't wear them again. Not worth the pain. Went with the Assos tiburu and WOW what a difference. That is the gold standard for me. That is another review. Save your money, IMO, buy something else.

Warm & Cozy

  • Size Bought: XL

These are great for late fall/early winter rides. Paired with leg warmers it's like riding with tights but the fit is much better. I wish I had bought a pair of these a long time ago--very comfy and keeps the legs nice and warm.

As others have stated the legs on these are loooong. I am 6'2 and take a size XL for all Castelli bibs--including these. The legs go all the way down to my knees, even for a tall guy like myself. Doesn't bother me because if I'm wearing these I'm going to be wearing knee warmers or leg warmers underneath. But if you plan on going without warmers, these will definitely spoil your hard- earned tan line.

On the positive, the straps on these are super stretchy and comfy. Might buy a second pair.

Regular thermal or Nanoflex shorts?

  • Familiarity:I've put it through the wringer
  • Fit:True to size
  • Size Bought: Small

Other reviews have covered these shorts exhaustively. I've purchased four over the past 2 years and have these comments:
1. I'm 5'4" and weigh 127 lbs. Live in Seattle and commute every day, rain and/or shine and these shorts endure wear during wet/cold days here. The shorts have held up very well except for the iron-on logos. Believe it or not, I've taken to gluing the "undone" corners of the lettering with fabric/vinyl cement (I must have some serious OCD or past life regression issues. Probably both).
2. Castelli's "Care" info on their website says that the DWR and Nanoflex treatment will hold up for "40 - 50 washings". I haven't washed them as many times but repellency seemed quite a bit less after 5 or so washings. Castelli recommends washing (machine or hand), then tumble dry under low heat for 20 minutes or pressing with a warm iron. I've tried both and the results are OK. What works best for me is to wash with NikWax Tech Wash followed (while wet) with NikWax TXDirect, then tumble dry for 20 minutes. Afterwards, repellency was like-new and haven't had to be re-treated so far this winter.
3. Fit: When new, the shorts were very, very tight. Over time, they've loosened up a little bit. I'm glad I had stuck with size small as opposed to sizing up.
4. Call of Nature: it would be helpful if if the bib fronts were cut a little lower to facilitate irrigation.
5. Other: The leg grippers do a great job with knee or leg warmers (especially the Nanoflex warmers and their silicone grippers). The hems of the shorts don't ride up over the warmers wet or dry. I've used them without the warmers and the grippers didn't irritate me (full disclosure: I shave). Inseam length: these are cut longer than my Pearl Izumi PRO shorts. However, the longer length is a nice interface with the Nanoflex warmers. Again, the grippers stay put and the warmers don't sag.
6. Pad: three of my shorts purchased last year have the same pad (Kiss3). The 4th pair, purchased in November this year, has a different pad labeled Air which. may be the Kiss Air spec'd for the current Nanoflex 2 shorts. In any event, these Kiss pads hold up well in cold/wet conditions.

Overall: So far, the Nanoflex bib shorts have been a great value. If you had the fortune of purchasing these during the recent 50% Off Sale, they're unbeatable. I've several thermal shorts from other companies that haven't seen use in wet or transitional conditions last winter or this winter because the Nanoflex shorts have the range the others don't possess.

Good Price, Cool Bibs

  • Familiarity:I've used it several times
  • Fit:Runs small
  • Size Bought: XL

Picked these up for cold winter riding. True to the description, there's a little extra material and lining to keep me warm on cold days. Perfect combo for leg warmers on a cold day. They are a bit longer than normal castelli bibs on the thighs, but that matches well for leg warmers. Definitely not a summer bib!

Great quality and fit

  • Familiarity:I've used it several times
  • Fit:Runs small

Thin, light but quite warm and it breathes well. xxl fits just fine. I wear XL Pearl Izumi bibs but have to go up a size for Castello. Legs are a bit longer than most but not a issue at my height.

Great winter bibs

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

Wanted to try out some winter weight bibshorts, for more versatility with leg and knee warmers. These have performed very well, have used in low 40s to 50s temps with both knee and leg warmers. Nice chamois, fit well (33"W = large per table) and would recommend. They fit a little smaller than the summer versions, I've found the same thing with my Castelli knickers. Competitive Cyclist had great price and service. Logos, per Castelli fashion (!) have started to fall off already..

Almost perfect!

  • Familiarity:I've put it through the wringer
  • Fit:True to size
  • Size Bought: medium

Great winter/fall shorts. Medium is roughly the equivalent of an Assos medium so be ready for a tight fit off the bike; once on the bike, they fit perfectly. Can get them wet (within reason) and they won't get soaked. With medium embrocation, an alternative to knickers above 45 degrees.

Excellent winter bibs.

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

I've worn these on a 50-60 day and they were great. They were comfortable the whole ride. I never felt cold and it didn't get too hot. The Kiss 3 chamois is pretty comfy. I usually wear a large in Castelli and these were spot on in a large. The length seemed a little long all the way to the knee. Once I was on the bike it settled in just above the knee and was perfect.

Goofy Giro leg grippers

  • Familiarity:I returned this product before using it
  • Fit:Runs small
  • Size Bought: xxl

I have "average" size quads not noodle legs. I have never had a pair of cycling shorts/bibs be loose at the leg grippers. This pair it is which at least on me does not look right and it is too long and actually comes down on my knee. Also I wear a large in a Craft bib yet this Castelli bib short in a XXL is still kind of tight in the waist (I typically wear a 36 waist pant). Go figure. I wanted to like these but I will be returning them.

Great bib shorts

  • Familiarity:I've put it through the wringer
  • Fit:True to size
  • Size Bought: Large

For me the fit of these shorts is the same as other Castelli shorts or tights. For me they are true to size. I got these shorts because I fell in love with Castelli bib tights for winter riding. The quality, fit and finish are superb. They are very comfortable for long rides. I would recommend to my friends and I would buy them again.

Great Bibs for colder weather

  • Familiarity:I've used it several times
  • Fit:Runs small
  • Size Bought: xl

Love those bibs from temperatures in the low 30's to mid 60's they are very confortable and keep you just the right amount of warm. I just did the Sebring 12/24 hour bike race with them starting temperature of 34 F and they felt great had no problems with them all day. after 12 hours and 233 miles they were still comfortable. it runs small normally I buy size L for my Bibs but hose were great at XL.

Weird sizing but good product

  • Familiarity:I've used it several times

The size is as usual a bit off. I am a small in Assos/PI/Capo but a medium was pretty snug. The leg grippers were my primary sticking point as they are just too tight compared to the rest of the product. Overall though it does exactly what it is supposed to and is comfortable. The pad is one of the better ones on the market and the temperature tolerance is incredible. I use this for races in the single digits with tights or for spring rides when it starts at 45 and ends at 60. The legs are longer but that is a nice addition since it is a colder weather option, actually i liked the length after a few rides.



Overall just make sure to get your sizing right, but it will expand after a few rides so give it some time after the first try on.

Castelli's best

  • Familiarity:I've put it through the wringer
  • Fit:Runs small

In my opinion at least. These have held up the best. The Kiss3 chamois is more than adequate. Their performance in wet weather is simply impressive. Coupled with a pair of Nanoflex leg warmers and you are good to go into the 30s/40s.



Unlike my other Castelli pieces, the stitching has held up quite well.



Order your typical Castelli size, they tend to run small compared to other brands.

Very nice product

  • Familiarity:I've used it once or twice and have initial impressions
  • Fit:Runs small

I'm a bib convert. I've worn them a couple times and have found them very comfortable. They run a tad small compared to another brand (sample size of one other brand). I haven't ridden them in rain yet and will keep you folks posted when I do.

works as advertised.

  • Familiarity:I've put it through the wringer
  • Fit:True to size

I have used these on a couple extended rain rides. There is nothing worse on a rain ride than a soggy wet crotchular area with a soaked pad that feels like a wet diaper. Glad to report no soggy diaperness occurred. Water beads off like it is supposed to. Fits true to size. I am a size large in Castelli bibs, and a large was perfect here.

Winter Bibs

  • Familiarity:I've used it several times

These are really good winter bibs. The nanoflex fabric really does bead water like the description says. They are warm. They are tight enough to prevent leg warmers from slipping at all. The legs are really long (they go down until right above my knees), but I like this in these bibs because it provides extra coverage when the weather is nasty. They have a good chamois that keeps my bottom happy on 4 hour rides. All-in-all I would recommend these bibs to anyone looking for bibs for when the weather gets cold or rainy.

Typical Castelli quality BUT .....

  • Familiarity:I've used it several times

.... these shorts are crazy long! They are a full 8 cm longer in the leg than the 2 other pairs of Castelli bib shorts (same size) that I own. They are so long that the gripper irritates the back of my knees on multi-hour rides if I do not wear leg warmers. Other than the length, the fit is consistent with other Castelli products. The size guide in the specs is sensible.



The nanoflex fabric is excellent and warm. I wear these comfortably in the single digits (celsius). The pad is comfortable and well-placed, and overall construction is of good quality. They are very strong value for the money.

Long inseam is perfect

    Referring to Brian's post, I am about 140 lbs with a 34" inseam and these bibs fit great. The longer inseam gives me coverage that I usually can't find.
    A medium fits me fine. The chamois works well and has plenty of thickness but does not bunch up.
    I hate that they are more suitable for cold weather or I would buy several for year round.

    What is the difference between these bibs...

    What is the difference between these bibs and the Claudio bib short?

    I guess I'll answer my own question. The bibs have a fit that is very similar to the Claudio. The cut is not exactly the same, but very close. However, where the Claudio bibs used the silicone gripper on the inside of the leg to keep them in place, these bibs use the Giro++ (I think that's what they call it), which attaches at the end of the leg. The material for the legs seems to be cut to the same length as the Claudio, but with the Giro++ gripper they end up being about 2 inches longer. First impression was that they were almost comically long. I'm 5'9", 138 lbs, and the medium fits great everywhere, but this leg situation might be a deal-breaker. They would be fine if you were 140lbs with a 34" inseam and relatively short torso.