Description

Marin San Quentin 24″ Kids Dirt Jump Hardtail

A kid ready to size up from a 20″ bike deserves more than just bigger wheels bolted onto the same basic build, and the Marin San Quentin 24″ delivers a genuine step forward. Developed with input from freeride legend Matt Jones, it carries the dirt-jumping DNA of Marin’s Alcatraz into a hardcore, all-round hardtail built for a young rider ready to go further and faster. A Manitou J Unit air suspension fork with 100mm of travel gives real adjustability for a lighter rider’s weight, and for 2025/26, this build steps up to a Shimano CUES 9-speed drivetrain with an 11-46T cassette, a genuine upgrade in range and shift quality over a standard entry-level groupset. A one-piece seatpost and saddle combo keeps standover and ride height low, and kid-specific hydraulic disc brakes give real stopping confidence. Tubeless-compatible tyres round out a build that treats a 24″ wheel size kids’ bike as a serious step toward genuine mountain biking.

Marin San Quentin Jr 24 Overview

The San Quentin 24″ carries the same dirt-jumping design philosophy as the 20″ model in the line, scaled up for a taller young rider while stepping up several key components. Where the 20″ version runs an 8-speed Shimano Altus drivetrain, this 24″ build moves to Shimano’s newer CUES platform at 9-speed, giving a wider 11-46T cassette range and generally smoother, more durable shifting.

The Series 2 6061 aluminum frame is disc-specific and compatible with a 30.9mm dropper post, meaning it can be upgraded later even though it ships with an integrated saddle and post combo for lower standover height.

Features and Benefits of Marin San Quentin Jr 24

Manitou J Unit air suspension fork
A 100mm-travel air-sprung fork with adjustable rebound gives real tunability matched to a lighter rider’s weight, a meaningful step up from the fixed-rate coil forks common on kids’ bikes at this size.

Shimano CUES 9-speed drivetrain
Shimano’s newer CUES platform brings a wider 11-46T cassette range and generally smoother shift quality than older entry-level groupsets, giving a young rider genuine range for both climbing and faster sections.

Low standover, one-piece saddle and post
The integrated saddle and seatpost combo lowers both standover height and overall ride height, making mounting, dismounting, and stopping more confident, particularly important on a bike built for dirt jump-style riding.

Hydraulic disc brakes
Shimano MT200 hydraulic disc brakes with 160mm rotors give reliable, consistent stopping power suited to genuine trail and dirt jump use.

Tubeless-compatible tyres and wheels
Both the tyres and Marin’s aluminum double-wall wheels are tubeless-compatible, giving room to upgrade tyre setup later as a rider’s skill and terrain demands grow.

Dropper post ready
The frame’s 30.9mm dropper post compatibility means this bike can be upgraded from the stock integrated saddle/post combo as a rider’s skills progress.

Technical Specifications

Applications and Industries

1)  Dirt jump and pump track riding for a taller young rider

2) General trail riding for kids stepping up from a 20″ bike

3) Riders learning to use hydraulic disc brakes and wider-range shifting together

4) A step-up bike for kids outgrowing the San Quentin 20″

5) Families wanting a genuinely upgradeable kids’ bike with dropper post compatibility

Why Choose This Marin San Quentin 24″

Stepping up wheel size on a kids’ bike should mean a genuine upgrade, not just bigger wheels on the same basic parts. The San Quentin 24″ delivers that with a newer Shimano CUES 9-speed drivetrain, a wider gear range than the 20″ model’s 8-speed setup, and an adjustable air fork that can be tuned to a lighter rider’s actual weight. The low-standover integrated saddle keeps mounting and dismounting confident, and dropper post compatibility means the bike can grow with a rider’s skills rather than being replaced the moment they’re ready for more. For a family looking for a genuinely capable 24″ mountain bike, not a bigger-wheeled toy, this is a well-specced choice.

Quality Standards

Marin developed the San Quentin line with input from professional freerider Matt Jones, applying that real-world riding feedback to the 24″ version’s geometry and component choices.

Packaging Options

Bikes typically ship partially assembled in protective packaging, with final assembly (front wheel, handlebar alignment, brake bleeding) completed by a dealer or a capable home mechanic before first use.

Shipping and Export Information

Shipping timelines and export documentation vary by destination and order volume. Customers ordering internationally or in bulk should confirm current lead times and freight options directly with YM Racing.

Frequently Asked Questions

How much travel does the suspension fork have?
100mm, through a Manitou J Unit air-sprung fork with adjustable rebound, giving real tunability for a lighter rider’s weight.

What’s different between this and the San Quentin 20″?
Beyond the larger 24″ wheels, this build steps up to a Shimano CUES 9-speed drivetrain with an 11-46T cassette, versus the 20″ model’s 8-speed Shimano Altus setup.

Does this bike have hydraulic or mechanical brakes?
Hydraulic. It uses Shimano MT200 hydraulic disc brakes with 160mm rotors.

How many gears does it have?
9 speeds, through a Shimano CUES drivetrain with an 11-46T cassette range.

Can a dropper post be added later?
Yes. The frame is compatible with a 30.9mm dropper post, even though it ships with an integrated saddle and seatpost combo.

What does the one-piece saddle and post do?
It lowers standover and overall ride height, making it easier for a young rider to mount, dismount, and stop confidently.

Are the tyres and wheels tubeless-compatible?
Yes, both the Delium Versatile tyres and Marin’s aluminum wheels are tubeless-compatible.

What size is this bike?
It’s offered in one size (OS), built around 24″ wheels.

What colour does it come in?
Blue.

Is assembly required after delivery?
Yes. Bikes ship partly assembled, and final setup, including brake bleeding and handlebar alignment, should be completed by a shop or a capable home mechanic.

Conclusion

The Marin San Quentin 24″ gives a young rider a genuine step up, not just a bigger version of a smaller bike. An adjustable air fork, a newer Shimano CUES 9-speed drivetrain, and kid-specific hydraulic brakes deliver real capability, while the low-standover saddle and dropper post compatibility mean the bike can keep pace with a rider’s growing skills. For a family looking for a well-built, genuinely upgradeable 24″ mountain bike, this is a strong, thoughtfully specced choice.