Unlike conventional bib shorts, Gore’s Gernflow Liner Bib Shorts+ Mens are designed to be worn under clothing. Thanks to a thinner-than-usual mesh build, they offer a second skin feel that’s breathable and almost undetectable to the eye. While the straps feel a bit too heavy-duty, they're up there with the best MTB liner shorts on the market.
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Gore Fernflow Liner Bib Shorts+ Mens - Technical details
Gore created the Fernflow Liner Bib Shorts to be worn under baggy shorts or trousers to avoid overheating while offering plenty of comfort over lengthy rides. To do so, the shorts use a lot of mesh in their construction with mesh legs and straps.
Speaking of straps, they’re fixed to the shorts using a three-point anchoring system as the two straps anchor and two points at the front and one at the back.
Mesh is also used to form the three pockets found at the back and sides of the shorts. There are raw-cut hems with rather minimal silicone grippers that have been added for both security and comfort.
The Fernflow bib shorts use Gore’s Advanced Brand Core Seat Pad which uses a dual density material. The top is an 80kg/m3 open-cell foam with a soft cover that’s included to promote moisture control and the second, lower layer uses a 120 kg/m3 perforated open-cell foam. Overall, it’s claimed to be 10.5mm thick and there’s a male-specific pressure relief channel.
Gore Fernflow Liner Bib Shorts+ Mens - Performance
Gore has cut these bibs with its closest, form fit. This has been chosen to encourage moisture-wicking and thermal efficiency. It also aids with aerodynamics but as a bib that’s designed to be worn under shorts and pants, aero gains won’t be noticed.
I chose a medium bib and the fit is very good indeed. There aren’t any tight points anywhere, and it doesn’t feel as if I’ve been stuffed in. Something that I’ve come to appreciate is that the legs aren’t super long like they can be with conventional bibs. That means that they don’t need pulling up when slipping into a pair of knee pads.
As far as the main shorts part of the bibs go, it’s superbly comfortable. On the bike, it feels as if there’s nothing there – well, apart from the straps that is.
The top of the short portion sits low on the body, much like non-bibbed shorts and, where I may have packed on a few pounds this year, it can feel as if it’s digging in a little. And even though they’re made using a similar mesh as what’s found on the legs, it doesn’t work quite as seamlessly at the straps. They’re broad, noticeable and not the softest out there. They also sit quite wide on the shoulders which is more of an acquired taste but they’ve never slipped off, nevertheless.
As a rider who only rides in baggies, whether that’s on a gravel or mountain bike, I applaud the bib’s ability to fly under the radar when worn under shorts or trousers. When under shorts, they offer enhanced airflow that’s unattainable with bibs that aren’t built with quite as much mesh. Under trousers, airflow is restricted but as there’s minimal silicone and raw hems riders can still take full advantage of the comfort on offer.
It’s handy to have a bunch of extra pockets, too, but while useful, I’d rather have a normal pocket at the back. The rearwardmost pocket is built with a wide, double-entry design and, generally, that’s great but I often like to ride with a soft water bottle stuffed into the back pocket, and that’s not possible on this bib.
Gore Fernflow Liner Bib Shorts+ Mens - Verdict
Bib shorts that are designed especially for wear under clothing are few and far between but there are other options out there, such as Poc’s MTB Air Layer Bib Shorts which cost £5 less. These bibs are made using a mesh fabric which should offer comparable airflow but, importantly, they’re built with a taller waist. That should stop that digging-in feeling that I get with the Gore bibs.
Rapha offers the Men’s MTB Trail Cargo Bib Liner that’s also built to be worn under shorts. These get wider straps and a taller waist but they only get mesh at the legs. There are only two pockets here, too, so storage options aren’t so great. These will set you back £130.
If you only wear baggies but would like to take advantage of the greater security and comfort that only a bib short can offer, Gore’s Fernflow Liner Bib Shorts+ Mens make for an excellent choice. Airflow is excellent, as is comfort but, if like me, you’ve got a bit of a belly, you might find some discomfort around the top of the shorts and the pocket could be easier to access.