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  1. #1
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    New question here. How much faster will I be after dropping 6 lbs and going stiffer?

    After years of training on the road, my brother convinced me to race MTBs this year. So we've been doing a weekly MTB series. We started in Sport but were winning by 2-3 minutes, so we were asked to move up to Expert. In Expert I have a couple top ten finishes, but I'm loosing by a few minutes now to the top guys, who are all on hard tails and Epic type FS. I'm on an S-Works Stumpjumper FSR with dropper seat post (26.5lbs). Races are about 1hr10 minutes with 3,000 feet of hard climbing (about 1,000ft/lap). If I switched to a 2014 S-works Epic WC (20lbs) how much time do you think I would shave off my climbs? I figure some of the increased speed will be the weight difference (maybe 1.5 minutes), but some of it will be the increased stiffness (no idea how much time I will save here). On the Stumpjumper, I can't really stand and pedal even with the Brain closed because there is just too much bobbing. Thoughts?

  2. #2
    Formerly of Kent
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    The rate at which you go uphill boils down to three things, in order of precedence.

    Watts/kg, Crr, and CdA.

    Or, the amount of power you produce relative to body/bike weight, rolling resistance, and wind resistance.

    Ignoring the second and third, if you weigh 70kg, and your bike weighs 12kg, and you lost 3kg, for the same wattage (assuming same Crr and CdA), you'd see an improvement of 3.7%, at 300w.

    I'd also bet that you'd run slightly lower profile, faster tires on the 29er vs. the Stumpy. That will give you some speed, too. Uphill, downhill, on the flats.

    Air resistance/drag probably won't see much, if any improvement. I'd guess you'd be in more or less the same position on a 29er as you would on a 150mm AM bike.

    Have you tried putting a bit more air into the shock? It sounds like either the Brain needs to be serviced, or you aren't running enough pressure in your rear suspension.

  3. #3
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    I would check your shock like LeDuke says.

    "Every extra pound you carry above that weight makes you 15 to 20 seconds slower for each mile of a climb." Hunter Allen
    Find Your Ideal Cycling Body Weight | Bicycling Magazine

    A guy on my team has a coach (ex US Postal team member) who says that 1lb up a grade (6-7 degrees?) equals 3 watts.

  4. #4
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    Thanks guys. I forgot to mention that my Stumpy is a 2012, 29er model. I will try to look into my rear Brain shock, but I think it is working. There is just so much travel in the rear, that even locked out, it moves enough that I can feel it.
    I have a power meter in the cranks of my road bike. On an hour long HC climb I average around 295W (probably 310-320 on a 20 minutes effort). If I really gain the equivalent of 18W by dropping 6lbs, that would certainly make a difference. The part nobody has touched on yet is the difference a stiffer rear triangle makes that doesn't move with each pedal stroke. Hopefully someone who has gone from a Stumpjumper FSR to an Epic can give their personal experience.
    Last edited by rdalcanto; 08-24-2013 at 08:01 AM.

  5. #5
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    Did you try adjusting your rebound dampening?

    What model bike do you have exactly that weighs 26 lbs?

  6. #6
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    2012 S-Works Stumpjumper FSR 29er running tubeless.
    Specialized Bicycle Components

    I haven't messed with rebound damping since I got it.

  7. #7
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    Since I'm 170lbs, and don't jump off big things, I had the shop put the SL wheelset on instead of the standard carbon wheels that were supposed to come with my bike. That shaved a little weight off to get it to 26.5.

  8. #8
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    From what you are describing and what this Specialized video says 2008 Specialized BRAIN Technology - YouTube it makes me think that you have a couple of adjustments off - or at last resort have shock re-tuned to epic specs (see 1:10 in video). I realize this is not your model, but the 'brain' technology I am sure has only gotten better.

    I would go to LBS to see if they can help with settings (unfortunately, I amazed at what some guys at shops don't know or worse, think they know), or where you are located find an "expert' on suspension set-up or contact Specialized- just to make sure you are getting proper experience.

    Or you could have the rear shock sent back to Specialized Service Center for Epic 'specs' - see video below
    Specialized Service Center - YouTube

    A couple of guys (vets) on my team have high end full suspension bikes and they are dialed in with no one thinking of going back to hardtail and are all top finishers in Cat 1 / Expert. Admittedly they are on Trek Superfly 100's. One of our riders got one of these Superfly 100 Pro SL - Trek Bicycle I thought he said it weighed 21-22lbs out of the box

    But, if you really want to lose 6lbs...just don't expect to make up any time on downhills...

    Let me know end result - good luck
    Last edited by scottz123; 08-25-2013 at 06:45 AM.

  9. #9
    mnoutain bkie rdier
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    Big question is: "How will you descend on a hard tail?" If you end up way slower on the descents like many hard tail riders are when they switch over, then it could be a total wash.

    Also, you can't ignore the fitness gained while in process of losing said 6 lbs! You will be stronger and fitter AND lighter. That is a triple storm...haha.

    We all have a threshold at which we can lose too much weight and will see negative effects from it, but most of us will never see that happen. Check out the TdF and grand tour racers. I remember hearing one of the pro team coaches saying that the KOM guys are gonna be around 2 pounds per inch tall. So, someone who is 5'10" and looking for solid hill stage finishes should be around 2 X 70" = 140lbs. Yikes!

    I am 5'10 and race Cat 1 in So. Calif. I have raced between 147lbs and 152lbs. I actually feel stronger and fitter at the 152 lb range for some reason.

  10. #10
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    How much faster will I be after dropping 6 lbs and going stiffer?

    How much do you weigh?

    You can estimate the time savings from weight loss whilst climbing if you know the combined rider & bike weight, along with details of the climb using the analytic cycling calculators:

    http://www.analyticcycling.com/Force...ight_Page.html

    If you're finding that the suspension on your S-Works Stumpjumper FSR feels too soft you can firm it up by over pressuring the rear shock. Ignore the rear brain shock's autosag function and keep adding pressure until the bike pedals acceptably. You won't get full suspension travel with a race setup like that but it's only a minor tradeoff which should be outweighed by the improved pedaling.

    Adding additional rebound damping can sometimes make it feel better too, as additional rebound damping will stop the rear suspension bobbing as violently.

  11. #11
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    Thanks for the replies. I vary between 170-172 pounds, 6ft tall, with broad shoulders. At 170lb I have very little body fat. My abs, back, etc. are totally ripped. I don't lift upper body weights, but I still look twice as muscular in the upper body as my little bro who is 5'10, and 150lbs. Just to clarify, the 6lb weight loss will come by getting the new S-Works Epic WC, so I will be a little slower downhill, but hopefully not as bad as if I went to a hard tail. More than half our races as at either Solitude or Snowbird ski resorts, and some of the downhills are narly with tons of rocks. No way I could fly down those on a hard tail and live....

  12. #12
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    Quote Originally Posted by rdalcanto View Post
    Just to clarify, the 6lb weight loss will come by getting the new S-Works Epic WC.
    Yes - you will be faster with the 6lb weight loss and 'epic XC spec rear suspension' and not give up much if any on descents.

    I would still suggest taking time to help you get suspension dialed in with either bike.

    None of the FS guys I know just hop on the bike and go right out of the shop - some time is spent setting up suspension.

  13. #13
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    Quote Originally Posted by rdalcanto View Post
    More than half our races as at either Solitude or Snowbird ski resorts, and some of the downhills are narly with tons of rocks. No way I could fly down those on a hard tail and live....
    I race a lot at the Snowbasin series and I believe these races are similar format. It's more up and down like Olympic XC, rather than the ICUPs which are big climb/big decent.

    I've collected quite a bit of Strava data from Snowbasin midweeks from last couple years switching between two bikes:
    -Cannondale Flash - 21 pounds
    -Giant Anthem 29er - 24.7 pounds (with Lefty fork)

    So roughly 4 pound difference. The data said that I was faster uphill with the Flash just by 5 or so seconds, but the difference isn't that big because the climbs are so short (4 minutes or so).

    But the downhill difference is pretty big. 10s+ advantage with the Anthem during short periods of time. Also the Flash had RaRa tires which I never liked, compared to heavier Conti mountain/X kings on the Anthem which corner like you're on rails (especially the older smaller mountain kings circa 2011).

    But I just couldn't descend the Flash fast through the high speed rocky sections; I got rattled like a Maraca.

    But I would say give the hardtail a try. I have a friend whose the fastest descender at our midweeks (in the B's) and he kills all of us on a Flash 29er. Last race he went from 7th place after first climb, to 1st place after 3 laps, all on DH skills. He says he prefers the lighter bike to mitigate his climbing weakness. Plus our midweek course gives a lot of advantage to a high skilled rider (the way it should be).
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  14. #14
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    How much faster will I be after dropping 6 lbs and going stiffer?

    Another option to consider would be a full suspension bike with a Fox iCD fork and rear shock.

    FOX FLOAT iCD riders

    What that gives you is a fully locked out climbing platform and then a fully open descending mode also. It could potentially work better than the Epic if you want something that will climb like a hardtail but still be hooked up on the descents.

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