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Alright smart-arse! Now you can turn your butt into a fitness tracker

Assos shorts come with a pocket specially for a Whoop 4.0 sensor: “the first smart cycling apparel to track your health and fitness data while you ride”

We're always telling you about collaborations here on, but this must be the weirdest of the year so far: Assos shorts specially designed to take a Whoop 4.0 sensor that monitors your fitness as you ride. All the cool kids are calling it the Whoop-Ass collab.*

2024 Whoop x Assos smart shorts - 2

If you’re not familiar with it, Whoop’s 4.0 fitness tracker is a wearable device that measures strain, recovery, and sleep. It collects data on your sleep, heart rate variability (the variation in the time interval between heartbeats), resting heart rate, and respiratory rate and gives you a daily recovery score. Whoop has no display or buttons. Instead, you check out the information on your smartphone.

2024 Whoop x Assos smart shorts - 5

The Whoop 4.0 is usually worn on a wristband, but various items of compatible clothing are available too. 

Now Whoop has partnered with Assos on Mille GT Whoop Bib Shorts C2 (men’s) and Uma GT Whoop Bib Shorts C2 (women’s). They each feature a pocket specially for your Whoop 4.0 device so it can monitor as you cycle. "Smart cycling apparel" is over-egging it a bit, then; these are shorts with a dinky pocket. 

> Read our review of the Assos Mille GT Bib Shorts C2 

“The first-of-its-kind cycling garments will solve the key problems often noted by cyclists by providing enhanced flexibility, comfort and the same accurate data collection as the device on their wrist,” says Whoop.

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“There were five pocket locations across the body that were tested in order to choose the optimal location for data and comfort on cyclists, and ensure that the new cycling bib was as accurate as a Whoop on a rider’s wrist. The final location—a left mid-centre glute pocket—emerged as the optimal choice.”

In short, it sits on your butt. Cheeky!

“One key advantage of these cycling shorts is their ability to remain securely in place, ensuring consistent and reliable data capture—even in the most demanding conditions,” says Whoop.

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When we reviewed the Assos Mille GT Bib Shorts C2 – minus the Whoop pocket – we praised the performance, fit, and super-comfy pad and awarded a 9/10 rating. These are definitely high-quality shorts.

> Best cycling bib shorts 2024 — enhance your comfort in the saddle with these top picks 

The Assos x Whoop shorts are priced at £145 and can be bought on and, and in Assos stores.

* They’re not.

Mat has been in cycling media since 1996, on titles including BikeRadar, Total Bike, Total Mountain Bike, What Mountain Bike and Mountain Biking UK, and he has been editor of 220 Triathlon and Cycling Plus. Mat has been technical editor for over a decade, testing bikes, fettling the latest kit, and trying out the most up-to-the-minute clothing. He has won his category in Ironman UK 70.3 and finished on the podium in both marathons he has run. Mat is a Cambridge graduate who did a post-grad in magazine journalism, and he is a winner of the Cycling Media Award for Specialist Online Writer. Now over 50, he's riding road and gravel bikes most days for fun and fitness rather than training for competitions.

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mattw | 4 weeks ago

They should have called it a Flange.

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