It was back in 2016 when Jeffsy brought two firsts to YT Industries' lineup. It was the first trail bike in the brand's range, and it was the first to roll on 29-inch wheels. Now, years later it's adding more firsts to the list. Not only has the trail platform been upgraded but it also gets downtube storage, something we're yet to see on any other YT bike. Here are all of the details as well as a first ride review of the YT Industries Jeffsy MK3 Core 5.

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YT Industries has crafted the latest edition of the Jeffsy with the very same values as the original. As YT's trail bike, it has been built to take riders further than before while still fully capable of descending at full speed. To achieve this, the Jeffsy gets a boost in suspension travel: 150mm at the front at 145mm at the rear.

2023 yt jeffsy core 5 shock.jpg, by Liam Mercer

That suspension has been tweaked, too, as the bike now benefits from 105% anti-squat at the sag point that we're told drops away very quickly as the suspension moves deeper into its travel. This comes in a bid to avoid pedal kickback, as well as to boost traction and acceleration. Furthermore, progression at the end of the stroke has been turned up a notch for better performance on the descents.

Elsewhere, there have been a number of geometry tweaks to lengthen and slacken the bike but, importantly, YT has paid attention to the seat tube angle and how it affects each frame size at a specific saddle height. So from small up to double XL, the effective seat tube steepens in order to offer a 77.2-degree effective seat tube angle.

2023 yt jeffsy core 5 crank.jpg, by Liam Mercer

As for the rest of the geometry, a large frame gets a 475mm reach, a 65-degree head angle and a 343mm bottom bracket height. The chainstay is then semi-size specific as frames up to large come with a 437mm chainstay, and then XL and XXL frames get a longer 442mm chainstay. That's all adjustable via a flip-chip.

2023 yt jeffsy core 5 shock 2.jpg, by Liam Mercer

Perhaps the biggest surprise is the downtube-integrated storage. Found underneath a door on the upper of the downtube, this new storage can become home to neoprene frame bags that can store tools or anything else you would like. Thankfully, each end of the downtube interior gets separation walls and the lid is designed to be water-resistant with double-lid sealing. 

The introduction of this bike also includes the Thirstmaster 6000 bottle that comes with the bike as standard, as does a bottle cage.

Offering a quiet ride was a priority behind the new Jeffsy's design. As such, there's chainstay and seatstay protection but, importantly, a new downtube protection system, too. This pad is bolted to the frame and uses a foam layer underneath a plastic housing, which should dampen impact noise.

2023 yt jeffsy core 5 logo.jpg, by Liam Mercer

The YT Industries Jeffsy MK3 comes in five builds and two frame materials, carbon and alloy, all accommodating different price points. However, a couple of builds stand out as the Core 3 CF and Core 2 AL get the same componentry, just bolted onto an alloy or carbon frame.

The kind of kit you can find across the range comes from RockShox and FOX, with SRAM Transmission found on the pricier bikes and SRAM mechanical drivetrains found elsewhere.

Prices start at £2,500 and go up to £6,000 for the Core 5 build.

• www.yt-industries.com

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