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Assos T FI.13_S5 Bib Shorts

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Item # AAS0009

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Item # AAS0009


Regardless of whether you love or hate their fashionista print ad campaigns, you must give full credit to Assos for their role as pioneer in the bike industry. Before Assos' emergence in the late 1990's, the main qualifier to establish the quality of a bib short (made back then by companies like Pearl Izumi and Castelli) was the number of panels it had. It was as simple as simple could be: 4 panels = Weekend Warrior; 6 panels = Quality meets Value; 8 panels = Marvel of Engineering. Assos turned this formula on its head by championing cost-be-damned materials and complicated fabric patterning. They brought us unprecedented style; they brought us unprecedented comfort; they brought justification for unprecedented prices.

No bib short in the Assos line was more emblematic of their cost-blind approach than their FI.13 S2 model, first introduced in 2000. The S2 was priced at $280 at a time when other companies feared breaking the $175 barrier. And despite the gap in cost between the S2 and everything else, it instantly became our best selling bib short -- a trend that stayed constant for 7 years. Why was it so wildly popular? Like any high-quality piece of clothing, it made the wearer look dazzling. But beyond that was its technical attributes: Its elastic interface chamois proved to be a delight for rides of any length; and the cut of panels made them embrace our bodies with perfectly light tension. The fit, in short, was flawless.

Given our history with the S2, we were understandably attentive when Assos announced it would be discontinued for a new model, the F.I.13 S5. With the S5 Assos takes all of the signature qualities of the S2 and benchmarks them higher. The Executive Summary is this: In comparison to the S2, the S5 weighs nearly 20% less and has 20% less volume. According to Assos testing, the S5 puts nearly 25% less pressure on your genital area. The short panels and the chamois are made from fabric 35% more breathable than the S2, while offering nearly 20% more muscle compression.

The S5 is available in 2 colors, Black and White. In both colors you'll note the turquoise-colored webbing between the bib straps (worry not, it's not visible once you put a jersey on!) Assos calls the color klinik, and in fact it's a carbon mesh that reduced static between your jersey and the bibs, allowing you jersey and bibs to move on your body independently of each other as you pedal.

The side panels of the S5 are made from Assos' new A430 fabric. It offers superior venting in comparison to the A360 used on the S2. Amazingly, though, A430 provides better muscle compression than A360. And it wicks sweat substantially faster. Do the fingertip test when you pull the S5's out of the box -- the sheerness of the A430 tells the story. A fantastic detail here, though, is that Assos uses a different fabric on the inner thighs, A431. Why A431? It has less stretch than A430, keeping the chamois in a more stable position in your crotch. And it's a more durable fabric, too, in order to minimize sweat-induced fabric degradation and potential piling of the inner thigh fabric cause by rubbing against your saddle.

The front panel of the S5 is made from neither A430 nor A431. Rather, it's a high elastic fabric designed for a simple purpose: Reduction of pressure on your genitals You'll spend a lot less time mid-ride reaching down into your shorts to readjust yourself. Gone are the days of your shorts contorting your goods in unpleasant ways.

The fabrics of the S5 are new, but rest assured that it's built in Assos' long-perfected AEPD design. Yes, the S5 will pull in strange ways when you're standing in front of the mirror. But when you're bent over on the bike in a riding position, they feel glorious.

The key element of any bib short is its chamois. And the S5 holds nothing back here. The new FI.13 chamois is actually two separate pads with two separate stitchings. The layer next to your skin is softer than what you get on the S2. While it lacks in none of the elasticity of the original FI.13 chamois, it somehow feels less rubbery than the original. It's softer and it compresses less, which means when it stretches it's not under so much tension. In other words, when it's being stretched, it doesn't try to snap back into place, so it won't abrade your skin as much. The chamois is dimpled, too, to facilitate heat ventilation. You'll also note a new cut at the front of the chamois to further reduce genital pressure.

The straps on the S5 are lighter and more vented than the S2; the leg grippers are asymmetrical, with one leg getting silver and one black; and the packaging will blow you away -- it comes in a thermo-foam box with a small jar of Assos' legendary Chamois Cream as well as a small bottle of Active Wear Cleanser, plus a wash bag. Available in Black and in White in sizes Small-TIR.

Tech Specs

75% polyamide, 22% elastane, 3% carbon fiber
yes, FI.13_S5
Recommended Use:
cycling, training, racing
Manufacturer Warranty:

Size chart


Men's Apparel
Leg & Knee Warmers 0 I II
Height 4ft 11in - 5ft 2in
(150 - 159cm)
5ft 3in - 5ft 6in
(160 - 169cm)
5ft 7in - 5ft 10in
(170 - 179cm)
5ft 11in - 6ft 1in
(180 - 185cm)
6ft 1in - 6ft 3in
(186 - 190cm)
6ft 3in - 6ft 5in+
(191 - 195cm+)
XLG but wider
Arm Warmers 0 I II
Chest 35.4in
46.5+ in
How to Measure:
For best results, take measurements over your underwear.
Measure around the widest part of your chest.

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Best shorts I own

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

The quality of manufacture, the attention to detail, the fact that these are made by the 40-or-so folks employed by Assos and not outsourced to China speaks volumes on the fit, the finish and the quality control.
These are not made for sitting in a coffee shop - they are designed to work while you are ON THE BICYCLE..

I have put about 75 miles on these and already I don't want to wear anything other shorts I own

I wish I had more Assos gear, but I am not that wealthy..

Avg. ride time: 1h 9m per week
  • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.


  • Familiarity: I've put it through the wringer

The perfect bibs... the fit and comfort of these bibs is truly amazing. When Assos claims that they will 'click' into position when on the bike they aren't kidding. They feel a little tight and the straps feel too short when standing, but as soon as I get on the bike they disappear. Fantastic for warm and hot weather, the ventilated back panel is great. I've worn and washed my pair 50+ times and the still look and feel like new. Found them for a great price, but even at full price I wouldn't hesitate to buy them again. I'm 6'-1", 195 lbs and wear an XLG.

sizing is critical

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

so I am slightly larger also - not quite like Mike in the comment below, but I have a 34 waist and a 42 chest - just kinda bulkier build. In Castelli I run a large, In Giordana I run an XL. So i was perplexed on size so i went XL. the first ride was great and they are a phenomenal bib, but they are just too bulky in the pad. I should have stuck with large since the pad is slightly larger (an asset not a flaw) and would probably be happier. 4 hours with a chamois that is too large can rub you the wrong way.

Avg. ride time: 2h 41m per week
  • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

It's like having a But"t"ler

  • Familiarity: I've used it several times

That's all I've heard for years.......Assos is #1 in everything, blah, blah. Too expensive.......Not at all. Best bibs I've ever bought. Unreal. First time I rode them I put on 65 miles and everything was perfect. They truly are perfect. Here was the only hard decision. I'm a bigger biker. 6'2" - 225#. Big legs, not fat but not a 6 pack either. If I went by the size guide (And I did) I should be in the XLG's. Sooo, I tried the XLG's and they were very tight. Once I got them on they felt pretty good. Tight but good. Due to the size the legs were almost like compression shorts. Felt good. I just didn't think it was perfect. Soooo, went to the "Sears Husky" size and bought the TIR. Fit much better but I gotta tell ya, I did like the tighter compression feel of the smaller one. Wish there was an Assos Rep standing next to me to say Ya or Na. Highly Recommend.

Unanswered Question
Avg. ride time: 4h 16m per week
  • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

Can you tell me if the leg length is the...

Can you tell me if the leg length is the same as the Mille Regular leg

Some of the best bib shorts ever

  • Familiarity: I've used it several times

These bib shorts are amazing. In fact, they are the best I have ever worn. Everything you read about Assos in the reviews is true. It fits amazingly on the bike, it works, its durable, and its expensive. The fabric is on another level. If you have a store near you that carries these items, take a moment to stop buy and simply inspect the quality of Assos' products. Then, buy these!