The YT JEFFSY Pro 29 has been given a significant performance boost for the new season. YT have introduced the extra centimetre of travel, previously reserved for the flagship CF Pro Race model, across the range. We were very excited to see how this would make the bike fare against the competition.

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YT JEFFSY CF PRO | 29″ | 150/150 mm | 13.78 kg | € 3,899 | manufacturer website

The YT JEFFSY 29 looks like a bike that will happily tackle whatever you throw at it, and that’s before you even take a seat on it. The low slung carbon frame with its beefy head tube instils you with confidence the moment you see it. Of course, we would have preferred the CF Pro Race model, but unfortunately, it wasn’t available at the time of our test. Nonetheless, the JEFFSY Pro, priced at € 3,899, also has a very well considered spec. The 150 mm travel RockShox PIKE Select+ up front combined with a Super Deluxe Select+ at the rear are a proven combination. The SRAM G2 RSC brakes offer sufficient braking power for most trails, but heavy riders or those who use the JEFFSY for shuttling would be better off with CODE brakes. YT’s 150 mm Postman dropper performs smoothly but with the seat tube as short as it is, there would have been enough room for 170 mm version. We’re happy to see that in 2020 YT are speccing MAXXIS tires for the JEFFSY, fitting a Minion DHR II on the front and rear. The JEFFSY is available with 27.5” wheels or the 29ers we had on our test bike, comes in five sizes from S–XXL and in two different colourways.


€ 3,899


Fork RockShox Pike Select+
Rear Shock RockShox Super Deluxe Select+
Seatpost YT Postman 150 mm
Brakes SRAM G2 RSC 200/180 mm
Drivetrain SRAM GX Eagle 32/10-50
Stem E13 Plus 50
Handlebar E13 Plus 780 mm
Wheelset E13 TRS Plus

Technical Data

Weight 13,78 kg
Wheelsize 29"
Travel (f/r) 150/150 mm

We never put the flip chip in the high setting. The JEFFSY climbs well enough in the low setting and is lots of fun on every trail.
YT have revised the rubber plugs for the cable ports, but they kept coming loose on our test bike
Lacking support
The RockShox Super Deluxe Select+ lacks mid-stroke support on the YT. Since there is no way of adjusting the damping externally, we’d advise active riders to install additional volume spacers in the shock.
Very quiet
The YT JEFFSY makes a very high-quality impression overall. This is underlined by the lack of background noise – there’s no rattling to be heard here.
Lots of space on the dance floor
Thanks to the low-slung top tube, you’ve got lots of space. This instils you with confidence in steep terrain and motivates you to ride the bike very actively. We would just have liked an even longer dropper post.
Thanks to its width, the stubby, custom made Fidlock bottle can hold up to 600 ml.

Geometry of the YT JEFFSY Pro 29

Due to the short seat tube and the gradual increments in reach across the range of available sizes, you’ll usually be able to choose between two sizes. At 180 cm tall, our test riders opted for a size L, which fit perfectly. The reach is 470 mm, the head angle is a decent 66° and the seat tube angle is very steep at 77°. On sizes XL and XXL, the chainstay length increases from 435 mm across the other sizes to 440 mm. A flip chip allows you to adjust the angles by 0.5° though we kept the JEFFSY in the slack setting.

As befits a good trail bike, the JEFFSY climbs well too!

Seat tube 400 mm 415 mm 435 mm 460 mm 485 mm
Top tube 571 mm 592 mm 614 mm 637 mm 659 mm
Head tube 100 mm 105 mm 110 mm 120 mm 125 mm
Head angle 66,5°/67° 66,5°/67° 66,5°/67° 66,5°/67° 66,5°/67°
Seat angle 77,5°/78° 77,5°/78° 77,5°/78° 77,5°/78° 77,5°/78°
Chainstays 435 mm 435 mm 435 mm 440 mm 440 mm
Wheelbase 1,171 mm 1,193 mm 1,215 mm 1,244 mm 1,266 mm
Reach 434 mm 454 mm 474 mm 494 mm 514 mm
Stack 615 mm 620 mm 624 mm 633 mm 638 mm

YT JEFFSY Pro 29 on test

In the past, YT’s weren’t known for their pedalling efficiency on the climbs, but all that is set to change with the new JEFFSY. The pedalling position on the bike is super central, meaning that no matter how steep the climbs, you never feel too far back and can always keep the front wheel under control in technical sections. The suspension performs efficiently and we never felt the need to reach for the climb switch. We would have preferred a 30 t chainring up front and while lighter wheels would make the bike a little more spritely, the fitted ones are okay considering the price.

Stay off the brakes! The YT JEFFSY is happy at speed and doesn’t have to shy away from shuttle days either.

On the descents, the handling of the JEFFSY is extremely forgiving. The weight distribution on the bike is spot on, making it extremely balanced and intuitive through corners. Thanks to the bike’s roomy cockpit and massive standover clearance, you have a lot of freedom of movement, with the JEFFSY inviting you to drift around corners and ride the bike as loose as possible. The rear suspension performs sensitively and absorbs bumps with ease, but it lacks mid-stroke support when ridden actively or popping off obstacles. We’d advise installing a few volume spacers to compensate – even with them fitted, we were still able to make use of all the available travel.

Tuning tip: volume spacers in the shock | possibly smaller chainring | lighter wheels if desired | more powerful brakes if necessary

Helmet Giro Montaro | Glasses Smith Flywheel | Jersey Fox Ranger | Short Fox Ranger | Kneepads Fox Launch Pro | Shoes ION Rascal Select

How does the YT JEFFSY CF Pro compare to the competition?

The YT JEFFSY and the Nukeproof Reactor appeal to a very similar target group. Neither of them shows any climbing weaknesses worth mentioning, with the YT offering a little more traction and comfort. On the descents, the Nukeproof rides like it’s on rails, whereas the JEFFSY invites you to let the rear end break out and slide. With its increased mid-stroke support, the Nukeproof is a better choice on shaped flow trails.

Riding Characteristics



  1. sluggish
  2. efficient


  1. cumbersome
  2. playful


  1. nervous
  2. confident


  1. demanding
  2. balanced


  1. harsh
  2. plush

Fun Factor

  1. planted
  2. poppy

Value for money

  1. terrible
  2. very good

Intended Use









Conclusion of the YT JEFFSY Pro 29

The YT JEFFSY Pro 29 is quite rightly one of the most popular trail bikes on the market, offering capable handling on the descents as well as excellent climbing prowess. It’s an excellent package, rounded off by carefully chosen componentry, at a fair price. Our only criticism is the lack of support from the rear suspension.


  • balanced, confidence instilling and fun geometry
  • great value for money
  • excellent climber


  • rear suspension bobs when pedalling out of the saddle
  • weak brakes
  • cable port plugs kept coming loose

For more information head to

The test field

Click here for an overview of the best trail bike in test.

All bikes in review: Cannondale Habit Carbon 1 (Click for review) | Canyon Spectral CFR 9.0 SL (Click for review) | Giant Trance Advanced Pro 29 (Click for review) | Ibis Ripmo AXS (Click for review) | Nukeproof Reactor 290 (Click for review) | Norco Optic C1 (Click for review) | Orbea Occam M-LTD (Click for review) | Radon Slide Trail 10 (Click for review) | Santa Cruz Hightower CC X01 Reserve (Click for review) | Scott Genius 900 Tuned AXS (Click for review) | Specialized Levo SL Expert Carbon (Click for review) | Specialized S-Works Stumpjumper SRAM AXS 29 (Click for review) | Trek Fuel EX 9.9 X01 AXS Project ONE (Click for review) | Yeti SB130 TLR (Click for review)

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Words: Photos: Christoph Bayer, Finlay Anderson, Markus Frühmann, Jonas Müssig