Bikes up to 60% offWe monitor over 40,000 bikes daily to find the best prices
Today’s Deals2024 YT Industries
Jeffsy Primus 27
A 27.5″ aluminum frame mountain youth bike with upper mid-range components and sram g2 r hydraulic disc brakes.
Compare the full range
Manufacturer Price
$2,399| Weight | 33.7 lbs |
|---|---|
| Frame | Aluminum |
| Suspension | Full, 150 / 150mm |
| Fork | RockShox Lyrik |
| Shock | RockShox Deluxe Select |
| Wheels | 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" – 5'5"
None yet.
Do you have this bike? Help other riders make a decision about which size will work for them by sharing your own size and fit notes.
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.
off.road.ccFeedback?
View all reviews
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 · YT Industries
Its 145mm of rear travel utilizes the World Cup-winning V4L linkage, and with five sizes available, complete with size-specific chainstay lengths (437mm for S-L / 442mm for XL-XXL), there is an Uncaged 14 for all riders.
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
| Fork | ROCKSHOX LYRIK BASE, 27.5“ | 150 mm Travel | RC | 100 x 15 mm Axle | Offset 44 mm | Adjustable Rebound, Air Pressure Travel: 150mm Spring Type: Air |
|---|---|
| Shock | ROCKSHOX DELUXE SELECT, Shock Length: 230 mm | Shock Stroke: 60 mm ≙ 150 mm Travel | Adjustable Rebound, Air Pressure, Custom Tune 0L1 Travel: 150mm |
| Headset | ACROS AZX-576, High Cap | 2 Spacer 5 mm |
| Stem | E13 BASE 35, Length 40 mm | 35 mm Clamp | Rise 0° | 6061 AL |
| Handlebar | E13 BASE 35, Width 760 mm | Rise 20 mm | 9° 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 31.6 mm | 125 mm | Std. Remote I Adjustable drop 20 / 10 / 5 mm Type: Dropper |
| Grips | ODI ELITE MOTION V2.1, Lock On |
| Rear Derailleur | SRAM SX EAGLE, 12-speed |
|---|---|
| Crank | SRAM SX EAGLE, Crank Arm Length 165 mm | 32T | DUB |
| Shifters | SRAM SX EAGLE, 12-speed |
| Cassette | SRAM PG1210 Eagle, 11-50T | 12-speed |
| Brakes | SRAM G2 R, Rotor CENTERLINE Ø front 200 mm / rear 200 mm Adjustable Reach Type: SRAM G2 R Hydraulic Disc |
| Rims | CRANKBROTHERS Synthesis Enduro 2 Alloy, Aluminum Rims 27.5“ | Inner Width 31.5/29.5 mm | Front Hub 15 x 100mm Boost | Rear Hub 148 x 12 mm |
|---|---|
| Tires | FRONT: MAXXIS MINION DHF I REAR: MAXXIS MINION DHR II, Front: Tire Size 27.5“ x 2.4 I EXO Casing I 3C MaxxTerra Compound I Tubeless Ready I, Rear: Tire Size 27.5“ x 2.3 I EXO Casing I Dual Compound I Tubeless Ready |
First added July 17
Last updated February 15
Not listed for 477 days