Pas Normal Studios Mechanism Pro bib shorts review: Very lightweight materials make these great in the heat
The shorts and straps are incredibly lightweight with superb moisture wicking, ideal in heatwaves and turbo trainer sessions
A super warm-weather and turbo training bib short option that remains comfortable over longer-duration rides. Not as technically advanced as some, but they deliver solid performance and good value.
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Great breathability
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Comfortable chamois pad
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Grippers are effective and silicone free
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Straps are very lightweight
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Not as exciting as some other hot-weather specialists
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Colours can show sweat easily
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The Pas Normal Studios Mechanism Pro bib shorts represent the pinnacle of PNS’s best cycling shorts range, utilising the lightest weight and fastest moisture-wicking materials in its range to produce a pair of bib shorts designed for use across high-intensity and hot-weather riding.
The material on the straps is incredibly thin and lightweight
Design details
The shorts use a structurally mapped, variable 4D-stretch fabric that hugs the body for a ‘second skin’ feel. This material is incredibly lightweight and wicks moisture quickly for the demands of high-intensity riding or racing, and it's also designed to resist abrasion.
The hems feature a woven-in, silicone-free gripper to keep the shorts in place without the risk of irritation. Meanwhile, the straps use a very lightweight mesh structure to support the shoulders while improving breathability. A radio pocket is stitched into the back of the straps.
The pad is the four-layer ultralight foam chamois that PNS uses across its range of shorts. It features a variable number of foam layers, with more under the sit bones and fewer as you move outwards. This design avoids bulk around soft tissue areas, while the upper is antibacterial and low-friction to reduce discomfort on longer rides.
Five colour options are available, as well as this PAS edition, and sizes span XXS to XXL.
The large PAS logos are visible from the side and add to the visibility of the black shorts quite nicely
Performance
The Mechanism Pro shorts feel very soft and lightweight. The material is incredibly thin but not see-through, and it feels very soft against the skin. The woven-in grippers keep the shorts in place, impressively given the low compression around the hems. This theme continues up to the bib straps and rear panel, which are again incredibly thin and lightweight but still supportive.
Together, these make exceptionally good bib shorts for hotter environments. During peak heatwaves, these are the shorts I reach for when temperatures exceed 35˚C. They are also a favourite to use on the turbo for higher-intensity sessions thanks to the higher level of moisture wicking.
They don’t offer the same compression as the Mechanism shorts, but they are still plenty supportive for higher-intensity efforts.
Early on in the ride before the salt stains started show through as temperatures peaked at 37°C
One area where the shorts can struggle a bit is a side effect of one of their strengths. The shorts have brilliant moisture wicking, which again improves warm-weather performance. However, the moisture transfer makes sweat very visible on longer rides. In the black colourway this is not apparent, but the Iron Grey version suffers in this area quite badly.
I’m still a big fan of the chamois. The graduated layers of foam padding, based on the amount of support required, mean the pad isn't bulky, but it still provides good cushioning and vibration dampening under the sit bone area. The lower volume around the rest of the pad means that there is no excessive bulk. Meanwhile, the antibacterial upper layer and fast-drying nature of the pad aid performance on longer, hotter rides. Overall, I've used these shorts on rides in exceptionally warm weather for five hours or more. In these scenarios, the shorts performed exceptionally well.
Lightweight materials at the rear aid heat transfer nicely
Value
At £260/ $350, these are certainly a premium-priced pair of bib shorts. Given their high moisture-wicking and performance focus, comparable options include the Rapha Pro Team III shorts (£250), Assos Equipe Bolide RSR S11 (£295), MAAP Pro Bib 2.0 (£260), and Q36.5 Dottore Clima Pro (£300). However, outliers such as the Castelli Free Aero Race S (£199) undercut those options by a fair amount.
The standout performance element of the Mechanism Pro bib shorts is their performance in warmer conditions, as they excel beyond many of the competitors, and the only ones that come close cost a fair chunk more, with the Assos and Q36.5 offerings, plus the Rapha Ghost.
However, the shorts don’t offer anything particularly exciting compared to something like the Bolide RSR S11, as its pad is truly exceptional, especially in warm weather or in a more aggressive riding position. I also personally do like the greater compression of the standard Mechanism shorts, while they do a better job of not showing sweat in lighter colours.
These are certainly a good pair of shorts; they just don’t excite me particularly or stand out in the crowd. But at the same time, they are the pair I tend to reach for on hot rides and turbo rides.
Tech spec
- Price: £260/ $350
- Chamois style: Race
- Storage: None
- Leg type: Shorts
- Colours: Black (tested), Brown, Grey, Blue, Green, White
- Sizes: XXS, XS, S, M, L, XL, XXL
