XC racing on Stumpjumper FSR?

[flavourflav]

Hi,

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

Geometry:
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:?
Thanks

Filipe

 

[atamariz]

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!
AT

 

[metgt4]

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

Andrew