Marin San Quentin 20 2025 20" Kids Bike

We took our Matt Jones-inspired Marin San Quentin and shrunk it down to fit 20” wheels. It’s the perfect bike for kids who are ready for their first proper, hardcore hardtail mountain bike.

The Marin San Quentin 20”, just like the big kid’s version, shreds the boundaries of the mountain bike genres – doing it all with a huge splash of big air, speed and style.

Designed with the input of freeride legend Matt Jones, the San Quentin takes the DNA of our dirt-jumping Alcatraz and mutates it into a go-further and faster all-round, hardcore hardtail. The San Quentin 20” will feel just like a ‘grown up’ mountain bike to your little ripper, built with a stout Series 2 aluminum frame, 20” wheels, an SR Suntour XCM suspension fork, 8-speed Shimano drivetrain and kid’s specific hydraulic disc brakes.

Specification

Frame	Series 2 6061 Aluminum, 20” Wheels, Disc Specific, 135mm Dropouts
Fork	SR Suntour XCM 24 BOOST, 80mm Travel, Lockout, 110mm Axle Spacing
Rims	Marin, Double Wall Alloy, 25mm Internal
Rear Hub	Forged Aluminum, 32H, Disc Specific
Front Hub	Forged Aluminum, 32H, Disc Specific
Spokes	14g Stainless Steel
Tyres	Vee Tire Crown Gem, 20×2.6”, Wire Bead
Rear Derailleur	Shimano Altus
Shifter	MicroSHIFT TS39, 8-Speed, Thumb-Tap
Crankset	Forged Alloy, Narrow Wide 30T, 140mm
Bottom Bracket	Sealed Cartridge Bearings, Square Taper
Chain	KMC Z8
Cassette	Shimano 8-speed, 11-32T
Front Brake	Tektro HD-J285 Kid’s Specific Hydraulic Disc
Rear Brake	Tektro HD-J285 Kid’s Specific Hydraulic Disc
Handlebar	Marin Riser, 31.8 clamp, 30mm Rise, 590mm Width
Stem	Marin Alloy, 35mm
Grips	Marin MTB
Headset	FSA No. 10P
Seatpost	Marin Alloy, 30.9mm
Saddle	Marin Kids MTB
Pedals	Kids Specific Nylon Pedal

Specifications are subject to change without notice

Size Guide

Frame Size	Minimum Height	Maximum Height
One Size	110cm (3’8”)	130cm (4’4”)

We have developed our size guide from our selling experience and it may differ from the manufacturers guide. Please note, this is only a guide and if you have any concerns over sizing please get in contact

Geometry

Frame Size	One Size
A – Stack	499
B – Reach	310
C – Head Tube Angle	65°
D – Head Tube Length	90
E – Seat Tube Angle	75°
F – Seat Tube Length	308
G – Top Tube Effective	443.4
H – BB Height	260
I – BB Drop	10
J – Chain Stay	340
K – Wheel Base	922
L – Stand Over Height	540
M – Fork Offset	40
Seatpost Diameter	30.9
Handlebar Width	590
Stem Length	35
Crank Length	140

Want to compare the size of your current bike to this one? Read our Reach and Stack guide here.