2025 YT Jeffsy Core 1 Bike

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Specifications

Product

YT Jeffsy Core 1 Bike

Model Year

2025

Intended Use

Enduro / All-Mountain

Trail

Rider

Unisex

Sizes and Geometry

SM (low, high)

MD (low, high)

LG (low, high)

XL (low, high)

XXL (low, high)

View Full Geometry

Size	SM (low, high)	MD (low, high)	LG (low, high)	XL (low, high)	XXL (low, high)
Top Tube Length	578mm, 562mm	593mm, 585mm	609mm, 607mm	627mm, 630mm	645mm, 652mm
Head Tube Angle	65.0°, 65.6°	65.0°, 65.6°	65.0°, 65.6°	65.0°, 65.6°	65.0°, 65.6°
Head Tube Length	100mm	108mm	116mm	124mm	132mm
Seat Tube Angle	76.9°, 77.5°	77.5°, 78.1°	77.9°, 78.5°	78.3°, 78.9°	78.6°, 79.2°
Seat Tube Length	385mm	410mm	435mm	460mm	485mm
Bottom Bracket Height	343mm (33mm drop), 351mm (25mm drop)	343mm (33mm drop), 351mm (25mm drop)	343mm (33mm drop), 351mm (25mm drop)	343mm (33mm drop), 351mm (25mm drop)	343mm (33mm drop), 351mm (25mm drop)
Chainstay Length	437mm, 435mm	437mm, 435mm	437mm, 435mm	442mm, 440mm	442mm, 440mm
Wheelbase	1191mm, 1189mm	1214mm, 1213mm	1238mm, 1236mm	1266mm, 1265mm	1289mm, 1288mm
Standover	730mm, 738mm	728mm, 736mm	732mm, 740mm	738mm, 746mm	742mm, 750mm
Reach	435mm, 442mm	455mm, 462mm	475mm, 481mm	495mm, 501mm	515mm, 521mm
Stack	613mm, 608mm	620mm, 615mm	627mm, 622mm	634mm, 629mm	642mm, 636mm
Additional Info	• Geometry adjustable via two-position flip chip in rear shock mount • All specifications listed are with 150mm travel fork with 44mm offset

Sizes Additional Info

• Geometry adjustable via two-position flip chip in rear shock mount
• All specifications listed are with 150mm travel fork with 44mm offset

View Full Geometry

Size	SM (low, high)	MD (low, high)	LG (low, high)	XL (low, high)	XXL (low, high)
Top Tube Length	578mm, 562mm	593mm, 585mm	609mm, 607mm	627mm, 630mm	645mm, 652mm
Head Tube Angle	65.0°, 65.6°	65.0°, 65.6°	65.0°, 65.6°	65.0°, 65.6°	65.0°, 65.6°
Head Tube Length	100mm	108mm	116mm	124mm	132mm
Seat Tube Angle	76.9°, 77.5°	77.5°, 78.1°	77.9°, 78.5°	78.3°, 78.9°	78.6°, 79.2°
Seat Tube Length	385mm	410mm	435mm	460mm	485mm
Bottom Bracket Height	343mm (33mm drop), 351mm (25mm drop)	343mm (33mm drop), 351mm (25mm drop)	343mm (33mm drop), 351mm (25mm drop)	343mm (33mm drop), 351mm (25mm drop)	343mm (33mm drop), 351mm (25mm drop)
Chainstay Length	437mm, 435mm	437mm, 435mm	437mm, 435mm	442mm, 440mm	442mm, 440mm
Wheelbase	1191mm, 1189mm	1214mm, 1213mm	1238mm, 1236mm	1266mm, 1265mm	1289mm, 1288mm
Standover	730mm, 738mm	728mm, 736mm	732mm, 740mm	738mm, 746mm	742mm, 750mm
Reach	435mm, 442mm	455mm, 462mm	475mm, 481mm	495mm, 501mm	515mm, 521mm
Stack	613mm, 608mm	620mm, 615mm	627mm, 622mm	634mm, 629mm	642mm, 636mm
Additional Info	• Geometry adjustable via two-position flip chip in rear shock mount • All specifications listed are with 150mm travel fork with 44mm offset

Wheel Size

29"

Frame Material

Aluminum

Frame Material Details

Forged multi-butted aluminum alloy; molded seatstay, chainstay, and bolt-on lower down tube protection

Rear Travel

145mm

Rear Shock

Marzocchi Bomber Air, Sweep Adjust, custom tune, 210mm length x 55mm stroke

Fork

Marzocchi Bomber Z1, RAIL 2.0 damper, 36mm stanchions, 44mm offset

Fork Travel

150mm

Head Tube Diameter

Tapered, 1.125" top, 1.5" bottom

Headset

Cane Creek Series 10; ZS44 upper, ZS56 lower

Handlebar

YT, 780mm width, 30mm rise, 8° backsweep, 6° upsweep, 35mm clamp diameter

Stem

YT, 50mm length, 0° rise, 35mm bar clamp

Grips

ODI Elite Motion V2.1, lock-on

Brakes

SRAM DB8, 4-piston, SRAM CenterLine 200mm 6-bolt rotors

Brake Levers

SRAM DB8, tooled reach adjust

Drivetrain

Shifters

Shimano Deore M6100, 12-speed, RAPIDFIRE PLUS

Front Derailleur

None

Rear Derailleur

Shimano Deore M6100, 12-speed, SHADOW RD+

ISCG Tabs

ISCG05

Chainguide

None

Cranks

Shimano M512 Alloy, 170mm length

Chainrings

Shimano M512, 32 tooth

Bottom Bracket

92mm press-fit

Pedals

None

Chain

Shimano, 12-speed

Cassette

Shimano Deore M6100, 12-speed, 10-51 tooth

Rims

SUNringlé SR329 Trail Comp Alloy, 30mm inner width

Hubs

SUNringlé Trail Comp wheelset, 15mm x 110mm (Boost) front, 12mm x 148mm (Boost) rear with MICRO SPLINE driver

Spokes

SUNringlé Trail Comp wheelset

Tires

Front: Maxxis Minion DHF, 3C MaxxTerra compound, EXO+ casing, TR, 29" x 2.5"
Rear: Maxxis Minion DHR II, 3C MaxxTerra compound, EXO+ casing, TR, 29" x 2.4"

Saddle

YT Custom, 144mm width

Seatpost

YT Postman V2 dropper, 5/10/20mm adjustable travel, Shimano MT500 remote lever
Drop: 125mm (SM), 150mm (MD), 170mm (LG), 200mm (XL/XXL)

Seatpost Diameter

31.6mm

Seatpost Clamp

Single bolt

Rear Dropout / Hub Dimensions

12mm x 148mm (Boost)

Max. Tire Size

Bottle Cage Mounts

One inside front triangle, plus accessory mounts under top tube

Colors

Drip Yellow, Black Magic

Warranty

5 years frame

Weight

36 lb 6 oz (16,500 g)

Miscellaneous

• MKIII version
• V4L (Virtual 4-Link) rear suspension design
• Internal cable routing
• Geometry adjustable via two-position flip chip in rear shock mount
• SRAM UDH (Universal Derailleur Hanger)
• Weight given for size SM set up tubeless, without bottle/cage
• Includes Thirstmaster 6000 water bottle and side-load cage
• Includes removable HEX6 tool in rear axle
• EU/UK price: 2799 EUR/GBP
• Canadian price: 3999 CAD

Price

$2,799.00

More Info

YT Introduces the Updated Jeffsy Core Range (press release)

YT website

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Where To Buy
	Free U.S. shipping on everything. International shipping available. Some exclusions apply.	Browse available Bikes
	Free shipping on orders over $50 (contiguous U.S. only). International shipping available. Some exclusions apply.	Browse available Bikes
	Free shipping on orders over $50 (continental U.S. only). International shipping available. Some exclusions apply.	Browse available Bikes
	Free shipping on orders over $69 (continental U.S. only). International shipping available. Some exclusions apply.	Browse available Bikes
	Free standard UK delivery on orders over £50.	Browse available Bikes