by the Jockstrap Junkie

Rating: 9.6/10 (Average of the ratings below)

  • Daily Fit: 10/10
  • Sizing: 8/10
  • Construction: 10/10
  • Styling: 10/10
  • Daily Performance: 10/10

Pros: Legstraps don’t fold or twist, waistband doesn’t roll, the pouch is supportive and roomy, color scheme

Cons: Runs a bit small, I’m convinced most clothing designers use tape measures that are calibrated differently.

Recommendation: I made three separate purchases in 2018 that included the C-Theory jockstrap in different colors. After my first two in June, I added a few more. By making repeat purchases, definitely makes this jock hard to not recommend, so…get it!


I’ve worn C-IN2 underwear since C-IN2’s debut in 2005 and worn a lot of different styles from them. Mostly, I’ve been a satisfied customer of C-IN2; which, is why I have kept returning to the brand. Over the years, there have been a handful of styles that didn’t work well for me, but this goes to the factor of C-IN2 cannot make every style for every body type. Now, let’s get to the good part, the review. The best way to describe the styling of the C-Theory jockstrap is taking old Bike jockstrap and upgrading it to 2019 styling. The waistband has a nice, blocked color scheme with a bold, contrasting stripe at the bottom of the waistband and the C-IN2 logo reverse printing into the stripe. If you like a large logo on the waistband, C-IN2 didn’t disappoint as the logo takes up almost the entire 2-½” height of the waistband and the logo is centered on the front & not repeated. Of the 16 color combinations offered, I purchased five of them and C-IN2 didn’t fail me on these jockstraps.

I purchased my first two in June of 2018. Immediately, the C-Theory jockstraps made it into my rotation of underwear with a C-Theory jock getting worn at least once a week. These are a great all-around jocks for everyday wear including routine tasks of mowing the lawn, lifting weights, cardio, and even lounging around. As stated above, the waistbands don’t roll, which is good for those of us with the ever popular ‘dad bod’. Great feel as the pouch has just enough support but also roomy for the boys. Another benefit of the single-ply pouch is breathability, in which I tested several times over the summer doing yard work in the humid Great Lakes region.

The cut of the C-Theory jock is similar to the old Bike No. 10 jockstrap with a 2-½” waistband and ¾” leg straps that attach at the side of the hips. Pouch material is 97% cotton & 3% Spandex, features a knitted, single layer with a center seam. Stitching is well done and smooth where the leg straps attach to the waistband, and the leg strap seams don’t dig into your hips like some jockstraps with lesser quality legs straps do. One requirement I have in a jockstrap is that the leg straps don’t cut into my glutes, which the C-Theory jock did not.

Large is the size I purchased which fits well. I normally wear a 33”-34” in my jeans which I like to sit on my hips to give you a general sizing perspective. With C-IN2’s sizing, if you’re in doubt, purchase a size larger as I feel C-IN2 runs a hair small.


If you’re a fan of the old Bike jockstraps, I think you’ll be a fan of the C-IN2 C-Theory Jock as the styling is a nice update to an old classic. I’m glad I added these five jocks to my collection and will be a good addition to yours.

PAIR: C-IN2 C-Theory Jock

COLORS: Sixteen color combinations
FABRIC: 97% Cotton / 3% Spandex
SIZES: Extra Small (XS) 25-27” 64-69 cm

Small (S) 28-30” 71-76 cm

Medium (M) 31-33” 79-84 cm

Large (L) 34-36” 86-91 cm

Extra Large (XL) 37-39” 94-99 cm

COST: $22


Jockstrap Junkie Stats

5’9” (175 cm) – 195 lbs. (88.5 kg)

Jean Waist Size – 33”-34” (81 cm – 84 cm)

Build – Athletic with a small belly

Twig & Berries – average size; grower, not a shower





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