YT Jeffsy CF Pro first ride review£3,799.00

The big wheeler that promises even bigger riding

A 29in wheel trail bike might not have been quite what everyone was expecting from the German company YT, a brand well renowned for its big-hitting, long-travel bikes. Will its first foray into the world of big wheelers create the same buzz as its now legendary Capra though?

YT Jeffsy CF Pro spec overview

  • Frame: Jeffsy carbon 29"
  • Shock: Fox Float DPS Factory
  • Fork: Fox 34 Float
  • Rear derailleur: SRAM X01
  • Shifter: SRAMX01
  • Cassette: SRAM XG 1175
  • Chain: SRAM PCX1
  • Brakes: SRAM Guide Ultimate
  • Wheelset: DT Swiss XMC1200 Spline
  • Front and rear tyre: Onza Ibex
  • Stem: Renthal Apex
  • Handlebar: Renthal Fatbar carbon black
  • Saddle: SDG Circuit

YT Jeffsy CF Pro frame and equipment

YT wanted to ensure the Jeffsy fitted in with the rest of the bikes in its line-up, so designed it around a short stem and riser bar. The stumpy head tube also allows for the stem to be lifted/lowered on the steerer tube to help riders get bar height just where they want it.

The V4L suspension system pumps out 140mm of rear wheel travel, all of which is tamed using Fox’s Float DPS EVOL shock in a bid to deliver a supportive stroke that can be used to push hard and ride fast. There are two geometry settings that are easy enough to switch between thanks to the flip chip located in the rearmost shock mount, letting you slacken the head angle out from 68.9 to 67.6 degrees, which in turn drops the bottom bracket by 8mm.

A short stem and riser bar keep things aggressive
A short stem and riser bar keep things aggressive

Chainstay length is dependent upon which size frame you go for, with the small and medium sporting a 435mm chainstay while the large and extra-large use a lengthier 440mm offering in a bid to balance handling.

Other points to note include the Boost 12x148mm rear axle spacing, plenty of integrated chainstay protection, room for a water bottle (albeit the custom YT cage only) and, for the most part at least, external cable routing. Interestingly, although the back-end gets the Boost treatment, YT is using non-Boost (meaning the front wheel isn’t as stiff as it could be) 140mm Fox 34 forks and with the shorter offset up front.

The medium, large and extra-large Jeffsys all come with 150mm (rather than the 125mm on the size small) RockShox Reverb Stealth posts.

SRAM’s Guide Ultimate brakes offer plenty of stopping power
SRAM’s Guide Ultimate brakes offer plenty of stopping power

YT Jeffsy CF Pro ride impression

YT hasn’t gone crazy with the geometry, with a reach of 425mm in size medium being a little on the conservative side compared to some of the competition. When seated, the 592mm effective top tube when paired with the 50mm Renthal stem let us tackle steep technical climbs without the front wheel lifting or wandering. This coupled with the fact that the Jeffsy weighs just 12.66kg (27.9lb) and has little in the way of energy sapping suspension bob means that, if you’re willing to put the effort in, this thing flies up hills.

The Fox 34 fork and DPS rear shock feel controlled and comfortable
The Fox 34 fork and DPS rear shock feel controlled and comfortable

The well-proportioned geometry and 29in wheels mean the Jeffsy covers ground rapidly too, and laps up anything remotely technical in its path. It never feels gangly, perched or cumbersome when things get twisty either. After fiddling with the stem height a little and settling on our preferred bar height, we found we absolutely loved slinging the Jeffsy into turn after turn, happily putting our trust in the big, aggressively treaded Onza tyres.

It’s playful as well, with plenty of pop and support in the suspension, letting you rail turns and thump into heavier hits at speed when the terrain does rough up. While the 34 fork and DPS rear shock felt controlled and comfortable no matter what was going on under our tyres, the skinny RaceFace grips did feel a little harsh on really choppy terrain.

YT Jeffsy CF Pro early verdict

YT's Jeffsy CF Pro
YT's Jeffsy CF Pro

The Jeffsy is one seriously capable all-rounder and is as happy munching miles as it is being razzed down technical singletrack.

This article was originally published in What Mountain Bike magazine.

Rob Weaver

Technical Editor-in-Chief, UK
Rob started riding mountain bikes seriously in 1993 racing cross-country, though he quickly moved to downhill where he competed all over the world. He now spends most of his time riding trail bikes up and down hills. Occasionally he'll jump into an enduro race.
  • Age: 34
  • Height: 172cm / 5'8"
  • Weight: 68kg / 150lb
  • Discipline: Mountain
  • Preferred Terrain: Natural trails where the loam fills my shoes on each and every turn
  • Beer of Choice: Guinness

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