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″<\/strong> 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.<\/p>\n 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.<\/p>\n 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.<\/p>\n Manitou J Unit air suspension fork<\/strong> Shimano CUES 9-speed drivetrain<\/strong> Low standover, one-piece saddle and post<\/strong> Hydraulic disc brakes<\/strong> Tubeless-compatible tyres and wheels<\/strong> Dropper post ready<\/strong> 1)\u00a0 Dirt jump and pump track riding for a taller young rider<\/p>\n 2) General trail riding for kids stepping up from a 20″ bike<\/p>\n 3) Riders learning to use hydraulic disc brakes and wider-range shifting together<\/p>\n 4) A step-up bike for kids outgrowing the San Quentin 20″<\/p>\n 5) Families wanting a genuinely upgradeable kids’ bike with dropper post compatibility<\/p>\n 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.<\/p>\n 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.<\/p>\n 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.<\/p>\n 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.<\/a><\/p>\n How much travel does the suspension fork have?<\/strong> What’s different between this and the San Quentin 20″?<\/strong> Does this bike have hydraulic or mechanical brakes?<\/strong> How many gears does it have?<\/strong> Can a dropper post be added later?<\/strong> What does the one-piece saddle and post do?<\/strong> Are the tyres and wheels tubeless-compatible?<\/strong>Marin San Quentin Jr 24 Overview<\/h3>\n
Features and Benefits of Marin San Quentin Jr 24<\/h3>\n
\nA 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.<\/p>\n
\nShimano’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.<\/p>\n
\nThe 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.<\/p>\n
\nShimano MT200<\/a> hydraulic disc brakes with 160mm rotors give reliable, consistent stopping power suited to genuine trail and dirt jump use.<\/p>\n
\nBoth 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.<\/p>\n
\nThe 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.<\/p>\nTechnical Specifications<\/h3>\n
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\n \nComponent<\/th>\n Specification<\/th>\n<\/tr>\n<\/thead>\n \n Frame<\/td>\n Series 2 6061 Aluminum, 24″ wheels, disc specific, 30.9mm post\/dropper compatible<\/td>\n<\/tr>\n \n Fork<\/td>\n Manitou J Unit Sport, 24″, 100mm travel, air sprung, adjustable rebound, tapered steerer, 15x110mm axle<\/td>\n<\/tr>\n \n Headset<\/td>\n FSA No. 57E<\/td>\n<\/tr>\n \n Stem<\/td>\n Marin Alloy, 40mm<\/td>\n<\/tr>\n \n Handlebar<\/td>\n Marin Riser, 31.8mm clamp, 30mm rise, 580mm width<\/td>\n<\/tr>\n \n Grips<\/td>\n Marin MTB, small diameter<\/td>\n<\/tr>\n \n Brakes<\/td>\n Shimano MT200, hydraulic disc, 160mm rotor, front and rear<\/td>\n<\/tr>\n \n Tyres<\/td>\n Delium Versatile, 24″x2.4″, light construction, wire bead, tubeless compatible<\/td>\n<\/tr>\n \n Wheels<\/td>\n Marin Aluminum Double Wall, disc specific<\/td>\n<\/tr>\n \n Front\/Rear Hub<\/td>\n Forged aluminum, 32h, disc specific<\/td>\n<\/tr>\n \n Spokes<\/td>\n 14g black stainless steel<\/td>\n<\/tr>\n \n Rear Derailleur<\/td>\n Shimano CUES RD-U4000, 9-speed<\/td>\n<\/tr>\n \n Shift Levers<\/td>\n Shimano CUES SL-U4000, 9-speed<\/td>\n<\/tr>\n \n Chain<\/td>\n KMC X-Glide<\/td>\n<\/tr>\n \n Cassette<\/td>\n Shimano CUES CS-LG3000, 9-speed, 11-46T<\/td>\n<\/tr>\n \n Crankset<\/td>\n Forged alloy, narrow-wide 30T, 140mm<\/td>\n<\/tr>\n \n Bottom Bracket<\/td>\n Sealed cartridge bearings, square taper<\/td>\n<\/tr>\n \n Saddle<\/td>\n Marin one-piece saddle\/post combo, 27.2mm alloy post, integrated<\/td>\n<\/tr>\n \n Colours<\/td>\n Blue<\/strong><\/td>\n<\/tr>\n \n Sizes<\/td>\n OS (one size)<\/strong><\/td>\n<\/tr>\n \n Model Year<\/td>\n 2026<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n Applications and Industries<\/h3>\n
Why Choose This Marin San Quentin 24″<\/h3>\n
Quality Standards<\/h4>\n
Packaging Options<\/h4>\n
Shipping and Export Information<\/h4>\n
Frequently Asked Questions<\/h3>\n
\n100mm, through a Manitou J Unit air-sprung fork with adjustable rebound, giving real tunability for a lighter rider’s weight.<\/p>\n
\nBeyond 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.<\/p>\n
\nHydraulic. It uses Shimano MT200 hydraulic disc brakes with 160mm rotors.<\/p>\n
\n9 speeds, through a Shimano CUES drivetrain with an 11-46T cassette range.<\/p>\n
\nYes. The frame is compatible with a 30.9mm dropper post, even though it ships with an integrated saddle and seatpost combo.<\/p>\n
\nIt lowers standover and overall ride height, making it easier for a young rider to mount, dismount, and stop confidently.<\/p>\n
\nYes, both the Delium Versatile tyres and Marin’s aluminum wheels are tubeless-compatible.<\/p>\n