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Castelli Nanoflex Bib Shorts

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Item # CST2473

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Item # CST2473

Conquer winter in shorts

You simply can't beat the feeling of quality bib shorts. Unfortunately, they usually aren't practical to wear year round. However, Castelli has changed this with its Nanoflex Bib Shorts. With a fleecy lining and a water-resistant exterior, the Nanoflex Bib Shorts answer the call of the winter with resounding vigor.

Castelli's Nanoflex Bib Shorts are made from the exclusive Nanoflex fabric. Nanoflex is a water-resistant version of Castelli's ultra-warming Thermoflex fabric. The transformation process occurs when the Thermoflex fabric is coated with millions of nanofilaments to create a water-repellant surface. Water beads and slides when it comes in contact with Nanoflex, and, all the while, the Nanoflex Bib Shorts retain their warmth and wind-blocking prowess. Besides protecting you from rain and snow, the Nanoflex Bib Shorts give you the benefit of having lightweight, stretchy shorts that warm like a light jacket on your legs, and fit like you're off to the races. The Nanoflex also features a fleecy inner-lining that traps a layer of warm air on your skin while it wicks away moisture to the quick-drying Nanoflex surface. This process provides consistent warmth and dryness that you'll appreciate when it's in the 40s. The Nanoflex adds extra comfort by incorporating breathable mesh bib straps and the Kiss 3 pad. The Kiss chamois uses a seamless construction of brushed microfiber to avoid any chafing, and the pad is anatomically shaped to help follow your movements. The Kiss 3 also features a variable density design with more padding where you need it, and less where you don't. For winter use, we recommend covering up all of that exposed surface area with Castelli knee or leg warmers.

The Castelli Nanoflex Bib Shorts are available in six sizes from Small to XXX-Large and in the color Black.

  • Nanoflex water-resistant fabric
  • Kiss 3 chamois

Tech Specs

[body] NanoFlex, [straps] mesh
Manufacturer Warranty:
30 days

Size chart


Men's Apparel
 Small Medium Large X-Large 2X-Large 3X-Large
Chest  35.5 - 37in
(90.2 - 94.0cm)
37 - 38.5in
(94.0 - 97.8cm)
39 - 41in
(99.1 - 104.1cm)
41 - 43in
(104.1 - 109.2cm)
43 - 45in
(109.2 - 114.3cm)
45 - 47in
(114.3 - 119.4cm)
Waist 29.5 - 31.5in
(74.9 - 80.0cm)
31 - 33in
(78.7 - 83.8cm)
33 - 35.5in
(83.8 - 90.2cm)
35.5 - 37.5in
(90.2 - 95.3cm)
38.5 - 40.5in
(97.8 - 102.9cm)
41 - 43in
(104.1 - 109.2cm)
Hips 36.5 - 38.5in
(92.7 - 97.8cm)
38 - 40in
(96.5 - 101.6cm)
40 - 42in
(101.6 - 106.7cm)
42 - 44in
(106.7 - 111.8cm)
44 - 46in
(111.8 - 116.8cm)
46 - 48in
(116.8 - 121.9cm)
How to Measure:
For best results, take measurements over your underwear.
Measure under your arms, around the fullest part of your chest.
Measure around your natural waistline, keeping the tape a bit loose.
Measure around the fullest part of your body at the top of your legs.
Using pants that fit well, measure the crotch seam to the bottom of the leg.

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Here's what others have to say...


Great bib shorts

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

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

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

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.

Avg. ride time: 4h 51m per week
  • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

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.

Avg. ride time: 1h 23m per week
  • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

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.

Avg. ride time: 9h 25m per week
  • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

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.

Avg. ride time: 27m per week
  • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

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.

Avg. ride time: 9h 37m per week
  • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

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.

Responded on

I agree, the legs are just a tad too long, if they used a different gripping system and were 2-3cm shorter it would go from good to exceptional product.

Unanswered Question
Avg. ride time: 4h 28m per week
  • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

seems like they should make these in fluoro,...

seems like they should make these in fluoro, no?


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.


    Nice winter bibs

      I rode with these new bibs in 45 degree weather. I usually wear a large (170 lbs, 5' 10"), and these larges are pretty snug. The leg grippers are somewhat loose to allow for leg warmers to be worn underneath. I didn't experience any slip down of the leg warmers which has happened with other bibs. The fleece keeps you warmer than standard bibs and I was very comfortable in the temperature. I could see these being too warm in temperatures above 65.

      What is the difference between these bibs...

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

      Responded on

      I was wondering the same thing; I have the Claudios and love them, but want to make sure the fit hasn't changed before I order these.

      Responded on

      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.

      Responded on

      This bib short is most similar to the Free Aero with a longer inseam, which I think is perfect for colder weather and pairs perfect with the NanoFlex leg warmer.

      Responded on

      Hi - in terms of sizing, I wore a L in the Claudio bib shorts. In the Nanoflex bibs, I had to go to an XL. they are definitely different in the sizing.