XC racing on Stumpjumper FSR?

Discussion in 'Mountain Bikes' started by flavourflav, Mar 1, 2010.

  1. flavourflav

    flavourflav New Member

    Dec 7, 2009
    Likes Received:

    I have a 2009 Specialized Stumpjumper Comp, and am considering tweaking it a little to be more XC racing rather then a marathon bike .
    Specs as follows:
    FRAME Stumpjumper FSR M5 Manipulated Alloy frame 120mm travel
    REAR SHOCK Fox Triad, custom on-the-fly 3-position switch 1) lock out 2) Open 3) ProPedal pedal assisting damping, rebound adj., 7.25x1.75"
    FORK Fox Float 120 RL, 120mm travel, compression and rebound adj. w/ LO
    STEM Specialized adjustable rise, 31.8mm clamp, 3D forged w/ CNC finish
    HANDLEBARS Specialized XC low rise 31.8mm bar, 6066 butted alloy, 6 degree up, 8 degree backsweep, 640mm wide
    FRONT BRAKE Custom Avid Elixir R SL, S/M: 185mm, L/XL: 203mm rotor
    REAR BRAKE Custom Avid Elixir R SL, S/M: 160mm, L/XL: 185mm rotor
    BRAKE LEVERS Custom Avid Elixir R SL Hydraulic, tool-less adj. reach
    FRONT DERAILLEUR Shimano M660 SLX, DMD, top swing, dual pull
    REAR DERAILLEUR SRAM X-9, 9-speed, mid cage
    SHIFT LEVERS SRAM X-7, aluminum trigger, 9-speed
    CASSETTE Shimano HG61, 9-speed, 11-34t
    CHAIN SRAM PC-971, 9-speed w/Power Link
    CRANKSET Shimano XT
    Wheelset: Mavic Crossmax ST
    Front Tire : Specialized S-works The Captain 26x2.2 (tubeless)
    Rear Tire: Kenda Karma 26x1.95 UST

    Size M
    Seat Tube Length - Center to Top 445mm
    Top Tube Length (Horizontal) 587mm
    Top Tube Length (Actual) 565mm
    Chainstay Length 420mm
    Bottom Bracket Height - Low Setting 335mm
    Seat Tube Angle (Actual) - Low Setting 71°
    Seat Tube Angle (Effective) - Low Setting 74.5°
    Head Tube Angle - Low Setting 68.5°
    Wheel Base 1115mm
    Standover Height 728mm
    Head Tube Height 120mm
    Handlebar Width 640mm
    Stem Length 90mm
    Crank Length 175mm
    Seatpost Length 350mm

    I am thinking of tweaking it into more of a race bike with the following modifications:
    - Lowering front fork from 120 to 100 mm with spacer (checked with fox, and can be done inserting a spacer).
    -Replacing stem and handlebars with KCNC bone flat 600mm handlebars, and 90 mm kcnc team issue 90 mm 5º stem (inverted).

    -Replacing stock tires with Schwalbe Rocket Ron Evo 2.25 (front, mounted tubeless)
    And Racing Ralph 2.1 (rear, mounted tubeless) (for wight reduction, and better grip).

    -KCNC ti pro lite seat post (for weight reduction)

    Current Weight = 12kg (26,5 lbs)
    Projected weight after changes = 11.1kg (24.5 lbs)
    Along with this, i will add a little air pressure to the rear shock, to make suspension travel front/rear more balanced.

    Do you believe this will be a good/efective setup, or is it better to just trade the bike for an Epic/Giant Anthem/Top Fuel/ETC:?


  2. atamariz

    atamariz New Member

    Jul 22, 2003
    Likes Received:
    In my own opinion, it would be much better to change your bike for a more specific xc racing model. Maybe a much lighter carbon fiber frame. For most xc races a top model hard tail or a short travel (80-100mm)double suspension bike are the best options.
    If you are not concentrating 100% in XC racing, and want to keep riding some trails and a bit of all mountain, leave your Stumpy the way it is know. Based on Specialized information, the Stumpjumper will give you a 50/50 efficiency on climbing/descending. For a lighter bike with better climbing and pedal response I recommend a Stumpjumper HT (high end, possibly a carbon fiber frame) or an Epic. Both of this will give an estimated 70/30 efficiency on climbing/descending.
    Try racing on your Stumpjumper FSR the way it is know, and you will find out yourself what is the kind of bike you really need.
    Just my opinion.
    Cheers from Mexico City!
  3. metgt4

    metgt4 New Member

    Jun 5, 2010
    Likes Received:
    My team mate rode TransRockies on a stumpy last year and had no problems finishing with a respectable time. I'd agree with the last post and say keep your stumpy he way it is and put he money you would have spent on upgrades toward a more xc race specific bike. Plus, the more you climb with the specialized, the easier it will be when you get a race bike! Think of it as resistance training ;)