$389.99 (USD$)


    For real mountain bike performance, the Thumper is bang on! The aluminum frame and quality components will satisfy every kid’s taste for dirt. With 50 mm of travel — more than most! — the Spinner fork offer real damping performance. Plus, a stable geometry ensures the Thumper is easy and safe to ride. Even the crank and saddle are sized specifically for a 20” bike, so you know the fit is as good as the ride.

    • 50 mm Spinner fork has more travel and better damping for real trail performance
    • Double-wall alloy rims and Kenda Smallblock 8 tires are light, tough and durable
    • Youth-sized components deliver on fit and safety
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    Frame Opus 6061 Aluminum
    Fork Spinner Grind 50 mm
    Weight (lb) 23.4
    Sizes 20"
    Color(s) Mirror Green
    Shifters SRAM 3.0 Twist 7
    Front Derailleur N/A
    Rear Derailleur SRAM X3
    Brakes Tektro V-Brake
    Brake Levers Tektro Alloy
    Crank Samox Alloy 127 mm
    Chainrings 36
    Bottom Bracket 5 pc Steel
    Cassette Shimano Tourney 14-34
    Chain KMC Z51
    Headset VP Semi-Integrated Sealed
    Handlebar Opus Junior 25.4
    Stem Promax 60 mm 15°
    Grips/Tape Opus Kraton
    Saddle Opus Junior
    Seatpost Opus Junior 27.2 x 300
    Wheels/Rims Ace Double wall
    Hubs Joytech
    Tires Kenda Smallblock Eight 20 x 1.75
    Pedals Wellgo Resin


    Geometry diagram
    Riders's height  
    ± cm  
    ± 0"  
    Size (cm)  
    S - Seat tube (effective center-center in mm) 305
    TT - top tube (effective center-center in mm) 455
    HT - Head tube (mm) 100
    HA - Head angle (mm) 71
    SA - Seat angle (mm) 74
    CS - Chain stay (mm) 390
    D - BB drop (mm) 8
    ST - Stack (mm) 420
    RE - Reach (mm) 334
    SO - Stand over (mm) 524
    Handlebar width (mm) 540
    Stem length (mm) 60
    Crank length (mm) 127
    Geometry diagram
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