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Today’s Deals2024 YT Industries
Jeffsy CORE 1 MX
A 29″ / 27.5″ aluminum frame full suspension trail bike with upper mid-range components.
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Manufacturer Price
CA$6,999($5,040)| Weight | 32.2 lbs |
|---|---|
| Frame | Aluminum |
| Suspension | Full, 145 / 150mm |
| Fork | RockShox Pike RC |
| Shock | RockShox Deluxe Select |
| Wheels | 29″ / 27.5″ Aluminum |
| Drivetrain | 1 × 12 |
| Groupset | SX Eagle |
| Brakes | SRAM G2 R 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
Sep 2024
The YT Jeffsy Core 4 has excelled at being an all-round “grab and go” bike, regardless of what gets thrown in its way. Check out our review.
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.
May 2024 · Mike Kazimer
We see how the most affordable version of the Jeffsy handled Squamish's slippery trails.
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
On the heavier side for a trail bike
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.
| Fork | RockShox Pike, 29“ | 130 mm | Rush RC | 15 mm QR x 110 mm | 44 mm Offset Travel: 150mm |
|---|---|
| Shock | RockShox Deluxe Select, 210 x 55 mm | R | DebonAir+ | 0L1 Spacer Travel: 145mm |
| Bottom Bracket | SRAM DUB Pressfit, BB DUB PF 92 MTB |
| Headset | ACROS AZX, 586 Block Lock (S-M), 576 (L-XXL) I 2 Spacer 5 mm |
| Stem | RACE FACE AEFFECT R 35, Length 50 mm (S-M), 60 mm (L-XXL) | 35 mm Clamp | Rise +/-6° |
| Handlebar | RACE FACE AEFFECT R 35, Width 780 mm | Rise 20 mm | 9° Back Sweep | 5° Up Sweep | 7075 AL |
| Saddle | SDG BEL AIR Overland 3.0, YT Custom | Width 140 mm I Lux-Alloy Rail |
| Seatpost | YT POSTMAN V2, Ø 31,6mm I MMX-Remote | Adjustable drop 25/10/5mm | 100 mm (S) I 125 mm (M) | 150 mm (L) | 170 mm (XL) | 200mm (XXL) Type: Dropper |
| Grips | ODI ELITE MOTION V2.1, Lock On |
| Rear Derailleur | SRAM SX EAGLE, 12-speed |
|---|---|
| Crank | SRAM SX EAGLE, Crank Arm Length 170 mm (S), 175 mm (M-XXL) | 32T | DUB |
| Shifters | SRAM SX EAGLE, 12-speed |
| Cassette | SRAM XG 1210 Eagle, 11-50T | 12-speed |
| Brakes | SRAM G2 R, Rotor CENTERLINE Ø front 200 mm / rear 180 mm | Adjustable Reach Type: SRAM G2 R Hydraulic Disc |
| Rims | CRANKBROTHERS SYNTHESIS XCT ALLOY 2, Aluminium rims 29” | Front: Inner Width 26.5mm | 110 x 15mm | 6-Bolt, Rear: Inner Width 24.5mm | 148 x 12mm | 6-Bolt | Freehub HG |
|---|---|
| Tires | MAXXIS MINION DHR II, Front: 29’’ x 2.4 WT I 3C MaxxTerra I EXO I TR, Rear: 29’’ x 2.4 WT I Dual Compound I EXO I TR |
First added December 16
Last updated December 24
Not listed for 530 days