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Today’s Deals2024 YT Industries
Jeffsy CORE 4 29
A 29″ carbon frame full suspension trail bike with high-end components.
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Manufacturer Price
$5,499| Weight | 33.3 lbs |
|---|---|
| Frame | Carbon |
| Suspension | Full, 145 / 150mm |
| Fork | RockShox Lyrik Ultimate |
| Shock | RockShox Super Deluxe Ultimate |
| Wheels | 29″ Aluminum |
| Drivetrain | 1 × 12 Electronic |
| Groupset | GX Eagle Transmission |
| Brakes | SRAM Code RSC Hydraulic Disc |
| Seatpost | Dropper |
Based on build material and quality level of the frame, fork, wheelset, groupset, suspension system, and more.
Compare the full Jeffsy model range
View Comparison5'0" – 5'6"
5'3" – 5'10"
5'7" – 6'1"
5'11" – 6'5"
6'2" – 6'8"
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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.
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
Matte black carbon finish is easily scratched and scuffed
Lacks stability at high speeds
SRAM SX Eagle drivetrain required regular adjustment
The new Jeffsy is an excellent trail bike package that can handle tougher stuff too.
Bike PerfectThe JEFFSY turns every trail into a round of Wild Mouse. No other bike in the test is this much fun.
Enduro Mountainbike MagazineThe 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.
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Feb 2025 · Steve Fisher
YT Industries reconfigures their JEFFSY CORE builds for 2025, now offering the mid-range bikes with carbon or aluminum frames.
Feb 2025
Calling these bikes “all-new” might be a stretch, but there's no denying the incredible value and versatility.
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.
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
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
Aug 2024 · Rich Owen
Rich Owen was a big fan of the previous Jeffsy, so what does he think of the latest Core 4 version after months of using it as his daily driver?
Excellent ride-anywhere bike
Updated frame with internal storage
Sorted component package with wireless SRAM T-Type drivetrain
Rides lighter than its actual weight
Useful internal and external on-bike storage
Matte black carbon finish is easily scratched and scuffed
Not the biggest internal storage opening
Jul 2024
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. While the spec is hard to argue with and the value for money is excellent, it's worth paying attention to the frame sizing and geometry to get the ride you want. The bike could be improved further with a longer dropper post and a slacker head angle but YT has done a good job continuing to polish the already excellent Jeffsy.
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.
Jan 2024 · Simon Kohler
How did the YT JEFFSY CORE 5 fare in our big 2024 trail bike group test?
Trail bike with fun guarantee
Mind-boggling price/performance ratio
Super intuitive handling
Pure agility!
Countless clever frame details
No storage compartment on the alloy model
Jan 2024 · Dario DiGiulio
The Jeffsy boasts easy, intuitive handling, and now has in-frame snack storage.
Intuitive and easy handling
Active, grippy suspension feel
Quality frame with well-executed storage and accessories
Requires attention in very rough terrain
Some may wish for more supportive suspension
Stock frame storage bags could be improved
| Fork | ROCKSHOX LYRIK ULTIMATE, 29“ | 150 mm | Charger 3 | 15 x 110mm | 44 mm Offset Travel: 150mm Spring Type: Air |
|---|---|
| Shock | ROCKSHOX SDLX ULTIMATE, Shock Length: 210 mm | Shock Stroke: 55 mm | 145 mm Travel | RC2T | 0L2 Volume Reducer Travel: 145mm |
| 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/Black |
| Handlebar | RENTHAL AL2014, Width 780mm | Rise 30mm | 7° Back Sweep | 5° Up Sweep | 6061 AL |
| 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) Type: Dropper |
| Grips | ODI ELITE MOTION V2.1, Lock On |
| Rear Derailleur | SRAM GX EAGLE TRANSMISSION, 12-speed |
|---|---|
| Crank | SRAM GX EAGLE TRANSMISSION, Crank Arm Length 170 mm | 32T | 2 Guards DUB |
| Shifters | SRAM AXS ROCKER PADDLE, 12-speed |
| Cassette | SRAM GX EAGLE TRANSMISSION, 10-52T | T-Type | 12-speed |
| Brakes | SRAM CODE RSC, Rotor CENTERLINE | Front 200 mm / Rear 200 mm Adjustable Bite Point and Reach Type: SRAM Code RSC Hydraulic Disc |
| Rims | CRANKBROTHERS Synthesis Enduro Alloy, Front: Aluminum Rims 29“ | Inner Width 31,5 mm | Hub 110 x 15 mm |, Rear: Aluminum Rims 29“ | Inner Width 29,5 mm | Hub 148 x 12 mm | Freehub 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 |
First added October 25
Last updated February 1
Not listed for 491 days