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2024 YT Industries

Jeffsy CORE 5 29

A 29″ carbon frame full suspension trail bike with ultra high-end components.
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Manufacturer Price

$6,499
Weight32.6 lbs  
FrameCarbon
SuspensionFull, 145 / 150mm
ForkFox Factory Float 36
ShockFox Float X Factory
Wheels29″ Aluminum
Drivetrain1 × 12 Electronic
GroupsetX0 Eagle Transmission
BrakesSRAM Code RSC Hydraulic Disc
SeatpostDropper
Where to Buy
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Insights
Ride Feel

Based on frame geometry and build specs.

Terrain
easyextreme
Handling
nimblestable
Jeffsy CORE 5 29
Other Trail bikes
Gearing

A bike with lower gearing will be easier to ride up steep hills, while a higher top end means it will pedal faster down hills.

Lowest gear

(climbing)

28 mph

Jeffsy CORE 5 29

26 mph

Similar Bikes

Highest gear

(descending)

Spec Level

Based on build material and quality level of the frame, fork, wheelset, groupset, suspension system, and more.

Compare the full Jeffsy model range

View Comparison
Sizing
SM

5'0" – 5'6"

MD

5'3" – 5'10"

LG

5'7" – 6'1"

XL

5'11" – 6'5"

XXL

6'2" – 6'8"

Rider Fit Notes

None yet.

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Reviews

Summary

The YT Industries Jeffsy is a highly versatile trail bike that excels in both climbing and descending, offering a fun and agile ride. Its updated frame features internal storage and a sorted component package, making it a great value for the price. While it performs well on a variety of trails, some reviews note areas for improvement in stability and component durability.

Pros
  • Excellent ride-anywhere bike

  • Updated frame with internal storage

  • Sorted component package

  • Rides lighter than its actual weight

  • Versatile for both rowdy trail sessions and long days in the saddle

Cons
  • Matte black carbon finish is easily scratched and scuffed

  • Lacks stability at high speeds

  • SRAM SX Eagle drivetrain required regular adjustment

Key Quotes
The new Jeffsy is an excellent trail bike package that can handle tougher stuff too.
Bike Perfect logoBike Perfect
The JEFFSY turns every trail into a round of Wild Mouse. No other bike in the test is this much fun.
Enduro Mountainbike Magazine logoEnduro Mountainbike Magazine
The YT Jeffsy Mk3 Core 4 is a capable all-mountain bike which, thanks to its spec, has a bias towards descending but is equally able to climb.
off.road.cc logooff.road.cc

Feedback?

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Bikerumor
YT Updates the JEFFSY CORE Range With Carbon or Aluminum Frame Options

Feb 2025 · Steve Fisher

YT Industries reconfigures their JEFFSY CORE builds for 2025, now offering the mid-range bikes with carbon or aluminum frames.

Read Review

BIKE Magazine
The New YT Jeffsy Is Impressive, But Not for the Reasons You Might Think

Feb 2025

Calling these bikes “all-new” might be a stretch, but there's no denying the incredible value and versatility.

Read Review

Mountain Bike Action
BIG THINGS COME IN SMALL PACKAGES - YT JEFFSY PRIMUS JUNIOR REVIEW - Mountain Bike Action Magazine

Nov 2024 · Nelson

With a value spec of workhorse components, and putting higher-end components where it matters, this is a hard package to beat.

Highs
  • Top-notch paint quality and finish

  • Cleanly designed internal cable routing

  • V4L suspension design for great traction and efficient climbing

  • SRAM SX Eagle 12-speed with a broad gearing range

  • SRAM G2 R brakes with adjustable reach levers

  • YT Postman 100mm dropper seatpost enhances riding experience

  • Maxxis DHR II tires for excellent cornering and traction

  • Great value with workhorse components and higher-end components where it matters

Lows
  • SRAM SX Eagle drivetrain requires regular adjustment

  • 760mm-wide aluminum handlebar too wide for most kids

  • Significant seal friction in forks and shocks for lighter riders

  • Stiff 35mm aluminum handlebar may exacerbate feedback and control issues

Read Review

Pinkbike
Field Test: YT Jeffsy Core 1 - Where Value Meets Performance

May 2024 · Mike Kazimer

We see how the most affordable version of the Jeffsy handled Squamish's slippery trails.

Highs
  • Excellent value (even more so when it's on sale)

  • Very capable descender, while still remaining manageable on mellow terrain

  • Wild or mild paint options

Lows
  • On the heavier side for a trail bike

Read Review

Singletrack World
YT Jeffsy Core 4 review

Mar 2024 · Ben Haworth

The YT Jeffsy Core 4 is a bike that arrives in a box that is not quite perfect out of the box. BUT... there is loads of potential here.

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Enduro Mountainbike Magazine
The YT JEFFSY CORE 5 - In our big 2024 trail bike comparison test

Jan 2024 · Simon Kohler

How did the YT JEFFSY CORE 5 fare in our big 2024 trail bike group test?

Highs
  • Trail bike with fun guarantee

  • Mind-boggling price/performance ratio

  • Super intuitive handling

  • Pure agility!

  • Countless clever frame details

Lows
  • No storage compartment on the alloy model

Read Review

Bike Perfect
Hands on: 2024 YT Jeffsy Core 5 first ride review – downtube storage, T-type shifting, and one hell of a price tag

Oct 2023 · Jamie Darlow

YT has reworked its Jeffsy trail bike, adding more tech, more price, and better performance

Highs
  • Pedals better when sat down and stood up cranking

  • Frame is sleeker and now comes with internal storage

  • Bikes range from £2,500 up to £5,999 for Core 5

  • Amazing spec on Core 5, with Fox Factory suspension

Lows
  • Costs a bomb for a direct-sales bike

  • Frame storage door could be bigger

Read Review

off.road.cc
YT Industries Jeffsy 29 Core 3 review

Aug 2022

The YT Jeffsy 29 Core 3 is a very capable all-mountain bike which can handle the rough stuff but is equally at home on flow trails and jumps. While the specification list is solid for the money, it's worth paying extra attention to frame sizing and geometry to get the ride you want. With a longer dropper and some tougher tyres this bike has what it takes to be a real challenger when it comes to the best mountain bikes.

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Geometry
Specs
Build
Fork

FOX 36 FLOAT FACTORY, 29“ | 150 mm | GRIP2 | 15 x 110mm | 44 mm Offset

Travel150mm

Spring TypeAir

Shock

FOX FLOAT X FACTORY, Shock Length: 210 mm | Shock Stroke: 55 mm | 145 mm Travel | 2-Pos Lever | Custom Tune | 0.2 Spacer

Travel145mm

Bottom Bracket

SRAM DUB Pressfit, BB DUB PF 92 MTB WIDE

Headset

CANE CREEK SERIES 40, ZS44 ZS56 | High Cap | 2 Spacer 5mm

Stem

RENTHAL APEX 35, Length 50mm | 35mm Clamp | Rise +/-6° | Black/Gold

Handlebar

RENTHAL FATBAR 35, Width 780mm | Rise 30mm | 7° Back Sweep | 5° Up Sweep

Saddle

SDG BEL AIR 3.0, YT Custom | Width 140 mm I Lux-Alloy Rail

Seatpost

YT POSTMAN V2, Ø 31,6mmI MMX-Remote | Adjustable drop 20/10/5mm | 125 mm (S) I 150 mm (M) | 170 mm (L) | 200 mm (XL) | 230mm (XXL)

TypeDropper

Grips

ODI ELITE MOTION V2.1, Lock On

Groupset
Rear Derailleur

SRAM X0 EAGLE TRANSMISSION, 12-speed | T-Type

Crank

SRAM X0 EAGLE TRANSMISSION, Crank Arm Length 170 mm | 32T | 2 Guards DUB

Shifters

SRAM AXS ROCKER PADDLE, 12-speed

Cassette

SRAM X0 1295 TRANSMISSION, 10-52T | T-Type | 12-speed

Brakes

SRAM CODE RSC, Rotor HS2 | Front 200 mm / Rear 200 mm Adjustable Bite Point and Reach

TypeSRAM Code RSC Hydraulic Disc

Wheels
Rims

CRANKBROTHERS Synthesis Enduro Alloy I9 1/1, Front: Aluminum Rims 29“ | Inner Width 31,5 mm | Hub 110 x 15 mm | I9 1/1, Rear: Aluminum Rims 29“ | Inner Width 29,5 mm | Hub 148 x 12 mm | Freehub I9 1/1 XD

Tires

FRONT: MAXXIS DHF I REAR: MAXXIS MINION DHR II, Front: Tire Size 29“ x 2,50 I EXO+ Casing I 3C MaxxTerra Compound I Tubeless Ready I, Rear: Tire Size 29“ x 2,40 I EXO+ Casing I 3C MaxxTerra Compound I Tubeless Ready

Rider Notes
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First added October 25

Last updated February 1

Not listed for 496 days