YT Industries expands its kids' MTB range with the new Jeffsy Primus 27

Lennox Zimmermann sending it on the YT Jeffsy 27
(Image credit: YT Industries)

German brand YT Industries has expanded its Jeffsy Primus offering in the best kids mountain bike market with the addition of a new 27.5-inch model. YT say the new model is aimed to cater to taller or slightly older young shredders, and the 27 also aims to provide the best MTB young talent the same top-quality and high-performance mountain bikes tested to the same high standards as the adult Jeffsy range.

Although technically aimed at children with heights of 135 cm to 165 cm (or 4’5” – 5’5”), the pricing is currently $200 / £500 cheaper than the comparable Jeffsy Core 2 model (which costs $2,499 / £2,999), so for the shorter adult rider its also a money saving option worth considering.

The YT Jeffsy 27 MTB in Nox Blue

The Jeffsy 27 maybe small but comes with a top quality spec (Image credit: YT Industries)

YT says that like the existing Jeffsy Primus 24 and Jeffsy Primus 26 the new 27 is the real deal, coming with 150mm of travel front and rear and built around a bombproof aluminum frame. The frame also benefits from internal cable routing and inconspicuous chainsuck plates to protect the frame from damage caused by a dropped chain.

Stand-out features see a geometry-adjusting flip-chip at the rear shock mount, that allows riders to raise or lower the bottom bracket height between 13mm and 6mm which also alters the head tube angle from 66.2 degrees to its low position of 65.7 degrees. In addition, the seat tube angle alters between 77 and 76.4 degrees.

The Jeffsy Primus 27 build includes a RockShox Lyrik Base fork and a custom-tuned RockShox Deluxe Select Shock, SRAM SX Eagle 12-Speed Drivetrain with 11-50T cassette and 165mm cranks, and SRAM G2 R Brakes with 200mm rotors front and rear. 

Elsewhere, there's an e*thirteen cockpit, a YT Postman 125mm dropper post and SunRingle Duroc 35 wheels with Maxxis Minion DHF and DHR II tires.

Rider on the Jeffsy 27 in the woods

Shorter adult riders benefit with a big saving on the comparable Jeffsy Core 2 model (Image credit: YT Industries)

YT Jeffsy Primus 27 pricing and availability

The YT Jeffsy Primus 27 is priced at $2,399  / £2,499 / €2,399 and is only available in Nox Blue. The existing Jeffsey Primus 24 and 25 also remain in the lineup for 2023, and all are sold with a 5-year warranty with all the information at

YT Jeffsy Primus 27 specification

The new YT Jeffsy Primus 27 MTB in Nox Blue

(Image credit: YT Industries)
  • Frame: YT Alloy
  • Fork: Rockshox Lyrik Base 150 mm
  • Rear Shock: Rockshox Deluxe Select 150 mm Custom Tune 
  • Groupset: SRAM SX Eagle 12-speed
  • Wheels: Sunringle Duroc 35
  • Tyres: Maxxis Minion DHF Front Maxxis Minion DHR II 27.5” x 2.4
  • Brakes: SRAM GT2 R 200mm F/R
  • Bars: E13 Base 35 Alloy
  • Stem: E13 Base 35 Alloy 40mm
  • Saddle: SDG Bel Air 3.0
  • Seatpost: YT Postman dropper 125 mm internal
  • Sizes: One size
  • Colours: Nox Blue
  • Pricing: $2,399 / £2,499 / €2,399
Paul Brett
Staff writer

Paul Brett is a staff writer for He has been an avid cyclist for as long as he can remember, initially catching the mountain biking bug in the 1990s, and raced mountain bikes for over a decade before injury cut short a glittering career. He’s since developed an obsession for gravel riding and recently has dabbled in the dark art of cyclocross. A fan of the idea of bikepacking he has occasionally got involved and has ridden routes like the North Coast 500, Scotland and the Via Francigena (Pilgrim Route), Italy.

Current rides: Marin Alpine Trail 2, Ribble 725, Cube Stereo 160

Height: 175cm