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    Derailleurs

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    GX T-Type AXS Replacement Cage
    SRAM
    $140.00 $110.60
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    GX Transmission Eagle AXS Upgrade Kit
    SRAM
    $605.00 $484.00
    Save 16%
    Altus RD-M310 Rear Derailleur
    Altus RD-M310 Rear Derailleur
    Shimano
    $31.00 from $26.04
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    AXS Rear Derailleur Cover Kit Clutch
    AXS Rear Derailleur Cover Kit Clutch
    SRAM
    $15.00 from $13.43
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    Eagle 90 T-Type AXS Replacement Cage
    SRAM
    $95.00 $75.05
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    SRAM X0 Transmission AXS Rear Derailleur Cover Kit - Thunder Mountain Bikes
    SRAM X0 Transmission AXS Rear Derailleur Cover Kit - Thunder Mountain Bikes
    X0 Transmission AXS Rear Derailleur Cover Kit
    SRAM
    $25.00 $19.75
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    SRAM XX Transmission AXS Rear Derailleur Cover Kit - Thunder Mountain Bikes
    SRAM XX Transmission AXS Rear Derailleur Cover Kit - Thunder Mountain Bikes
    XX Transmission AXS Rear Derailleur Cover Kit
    SRAM
    $25.00 $19.75
    Save 21%
    SRAM X0 Transmission AXS Rear Derailleur Full Mount Bolt Kit - Thunder Mountain Bikes
    X0 Transmission AXS Rear Derailleur Full Mount Bolt Kit
    SRAM
    $35.00 $27.65
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    SRAM XX SL Transmission AXS Rear Derailleur Cage Assembly Kit - Thunder Mountain Bikes
    XX SL Transmission AXS Rear Derailleur Cage Assembly Kit
    SRAM
    $230.00 $181.70
    Save 21%
    GX Transmission AXS Rear Derailleur Full Mount Bolt Kit
    SRAM
    $20.00 $15.80
    Save 21%
    T-Type AXS Rear Derailleur Cage Kit
    SRAM
    $30.00 $23.70
    XTR RD-M9250 Pulley Set
    Shimano
    $58.00
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    Deore M6250 Rear Derailleur
    Deore M6250 Rear Derailleur
    Shimano
    $435.00
    Save 21%
    Eagle 90/70 T-Type Rear Derailleur Pulley Kit
    SRAM
    $20.00 $15.80
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    CUES RD-U8000-GS Rear Derailleur
    Shimano
    $85.00
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    CUES RD-U3020-SGS Rear Derailleur
    Shimano
    $40.00
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    SRAM XX Transmission AXS Rear Derailleur Cage Assembly Kit - Thunder Mountain Bikes
    XX Transmission AXS Rear Derailleur Cage Assembly Kit
    SRAM
    $205.00 $161.95
    Save 21%
    SRAM XX Transmission AXS Rear Derailleur Pulley Kit - Thunder Mountain Bikes
    SRAM XX Transmission AXS Rear Derailleur Pulley Kit - Thunder Mountain Bikes
    XX Transmission AXS Rear Derailleur Pulley Kit
    SRAM
    $90.00 $71.10
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    SRAM XX SL / XX / X0 Transmission AXS Rear Derailleur Inner Cage - Thunder Mountain Bikes
    SRAM XX SL / XX / X0 Transmission AXS Rear Derailleur Inner Cage - Thunder Mountain Bikes
    XX SL / XX / X0 Transmission AXS Rear Derailleur Inner Cage
    SRAM
    $40.00 $31.60
    Deore XT RD-M8250 Pulley Set
    Shimano
    $39.00

    Let customers speak for us

    from 2404 reviews
    xt di2 8250

    This upgrade is amazing. Everything you need to go wireless. Easy set up and precise shifting, smooth and quick. Doubt if i'll ever go back to cable/housing.

    Jay F.
    Deore XT DI2 M8250 Upgrade Kit
    Great price and fast shipping

    Thunder Mountain Bikes is my go place for on-line purchases. They always have what I need at great prices and extremely fast shipping. If Thunder Mountain and “Shop X” have the same price, I always choose Thunder Mountain for their fast shipping plus everyone that works there are great people

    Chris B.~.C.C.
    GX Eagle DUB Crankset
    Great wheel

    Smooth hub and great wheel for trail riding!!

    John S.
    Trail S Hydra Front Wheel

    These are the best crank boots, use them on all my Shimano cranks.

    Richard
    Shimano Crank Arm Protector Boots

    Shimano quality as usual, 5 stars.

    Richard
    Deore XT CN-M8100 (M8200) Chain

    Love how this adapter cleaned up the cockpit with my Shimano I-Spec EV brakes.

    Richard
    Triggy Handlebar Adaptor

    Love the grips

    Jerrod
    Megattack Grips

    Love the grips

    Jerrod
    Megattack Grips

    Love the grips

    Jerrod
    Megattack Grips
    Good product, great service

    The stem was exactly what I expected. The service was great and I would gladly do business with Thunder Mountain the next time I need more bike stuff!

    Bob W.
    Elite 35 Stem
    Works Great

    This replacement charging port cap works great! Unfortunately, replacing it on an Ari Nebo peak required me to take it to a bike shop to get it replaced.

    Ricardo D.
    Ride 60 Charge Port Cap
    Boing boing

    Awrsome service as always

    Rob L.
    Steel Coil Spring
    Fit My XO Alloy Cranks

    Fit, seem pretty robust.
    Turbo Levo4 Pro.

    Jerry
    Crank Arm Boots
    Quality Cable

    Only disappointment is that they sold out.
    Heavy duty, right angle works with any USB C device.

    Jerry
    USB C to A Cable
    Perfect!!!!!!

    Takes pressure of the weaker part of your pedal stroke. Great for long rides to save your knees!

    Robert H.
    SRAM T-Type Oval Chainring
    2356
    78