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  1. #1
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    Prophet flex help needed.

    Hello,
    Sorry to start a new thread on this subject but take into consideration my mountain biking newbie status. I just got back into riding last summer and rode an old '92 steel hardtail with no suspension at all. I have a prophet 3 on order that should be here by mid january. I did not experienced the flex problem first hand yet but I would like to make the necessary changes while the bike is already in the shop. I did search the forums for a solution to the well known flexy prophet rear end issue but still need some more precise informations.
    1) I have a 2008 prophet 3: can I use a 12mm thru axle hub on that frame (does it fit the holes in the frame or are they 9mm QR holes only?)
    2) Will replacing the rear hub with a 12mm thru axle hub really make the rear end stiffer? I was told by my LBS mechanic that the flex issue was mainly due to the frame design and that changing the rear hub would almost be useless. The rear wheel would be more firmly attached to the swingarm but that swingarm, even with a firmly attached rear wheel, would flex anyways. However, some of you had very good results with this solution... I would not want to spend 200$ to find out it is not really worth it. Is the stiffness increase worth the money?
    3) I can't afford Chris King hubs. Are Hope Pro II available in a thru axle version? Other good thru axle hubs? While I'm at it, matching rim suggestions?
    4) Is the flex really an issue for me? Will I notice it as a newbie? I'm 6' 195 pounds with gear. Occasional 2-3 feet jumps-drops maximum. No freeriding.
    Thank you very much.

  2. #2
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    Reputation: Dan Gerous's Avatar
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    1) Quick release, changing to a bolt on skewer can improve stiffness a bit though.
    2) Yes but you can't.
    3) Again, no thru axle.
    4) Maybe not. I never thought of the Prophet as a flexy bike. Sure there are stiffer bikes but the flex is not causing me any problem or even that much noticed. I'm no freerider though but have a torquey engine and it doesn't feel flexy when pedaling. Still, before shelling out more money on a bike that a few people think is flexy (most Prophet riders never complained about flex), I'd try it first, you may not even feel it (especially coming from a 92 steel hardtail, those were usually not stiff at all) or not think it's a bad thing. Make sure the rear wheel is well built and tensionned (many shop will check and re-tension the wheels on new bikes anyway) and I'm sure you'll enjoy the bike a lot!

    DAN.GEROUS.NET : MOUNTAIN BIKING : CYCLOCROSS : ROAD :

  3. #3
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    There's really not a whole lot you can do about the flex. Like Dan said, the standard Prophet doesn't support a thru-axle, so that's a no-go (well, you actually could get the swingarm from the Prophet MX for 12mm thru-axle support). A custom hand built wheelset with some quality rims like the DT5.1d will help a bit (not a lot), but won't cure the swingarm flexing. That's just the design of the bike, so nothing you can do about it. That being said, you can do 2-3 feet drops no problem, and it will probably feel stiffer than your steel hardtail. However, I found that the more my riding progressed, the more I could feel the flex, making me decide it was time to move on to a bigger, stiffer bike. But again, like Dan says, the only way to really find out is to test ride one and make up your own mind.

  4. #4
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    In my opinion the flex is due to the frame design; as such, all similarly constructed (long chainstay, single pivot) Cannondales should reflect this: Prophet, Perp, and Judge. I experience it on my Prophet and Judge; but hasn't really bothered me. The pros of these bikes outweigh the cons.

  5. #5
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    The only time flex is an issue is in cornering. (that's the only time there is lateral forces on the wheel, kinda like grabbing the wheel from the side and pushing and pulling on it.) A bike with a flexy rear end will not track true because the harder you corner the more the rear will flex causing the rear tire tracking to change. It would be wandering so you won't have pin point accuracy hitting your lines in the turns. If you don't race it shouldn't be an issue.

    Ever seen the strut braces on Mcpherson suspension on sport cars. Same principal. Average car owner won't be railing the car so they won't notice. A sport car owner pushing the car to max on corner will notice the difference which is why you see the strut braces.

    There are other times you might feel the flex like hitting drops crooked. These are momentary flex (less than a second) so it shouldn't affect performance.
    Last edited by racerzero; 12-21-2007 at 12:29 PM.

  6. #6
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    Glad to see the flex is not that dramatic. I'll wait before changing anything. Thanks. You guys are always very helpful.

  7. #7
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    Maybe it doesn't affect performance, but it does affect your confidence. When you feel the bike squirming in a (fast) corner, slipping off roots, or even riding on your average cobbled street, when you have the feeling that the frame is right on its limit when landing a jump slightly off camber, that's just not very confidence inspiring. Sure, you can live with it, but I'd rather not.

  8. #8
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    Quote Originally Posted by Boozzz
    Maybe it doesn't affect performance, but it does affect your confidence. When you feel the bike squirming in a (fast) corner, when you have the feeling that the frame is right on its limit when landing a jump slightly off camber, that's just not very confidence inspiring. Sure, you can live with it, but I'd rather not.
    That's why I also own a Gemini and Judge. On the hand it's actually good training pushing the Prophet to the limit because the bike gets out of control at a lower speed so you can learn to react and correct. (kinda like learning how to drift a car in a wet parking lot) Bad things happens when my Judge starts to squirm at planeing speeds

  9. #9
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    Again, that's the con of the Judge, but the pro - hammering through rock gardens and flying at speed - can make up for it.

  10. #10
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    Quote Originally Posted by Kevin G
    Again, that's the con of the Judge, but the pro - hammering through rock gardens and flying at speed - can make up for it.
    Not a con. Just meant when you lose control of the Judge you'll be at WARP speed. Losing control is at that speed is not a good thing because bad thing happens.

  11. #11
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    Thankfully I haven't lost control yet! Sometimes I wonder if my Judge has an engine; it just has a constant tendancy to FLY.

  12. #12
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    You are getting a pretty lightweight frame (5.25lb no shock).

    You will notice flex visually while cruising on pavement. Apply brakes, pedal harder -> more flex. Just look down at your seat tube/swingarm. So you are waisting some energy right there.

    If you are after a super light frame this is it if not research SC Heckler (about 0.75lb more in frame). I am not saying that it is stiffer, I didn't have the pleasure to ride it, so I do not know.

  13. #13
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    Quote Originally Posted by Kevin G
    Thankfully I haven't lost control yet!
    You're not going fast enough then mate

  14. #14
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    Lol!!! Lucky are those who have trails to really push it....

  15. #15
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    This is my off season favorite to plow the Judge through (Rough Go at Annadel in Santa Rosa, CA):



  16. #16
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    Quote Originally Posted by Kevin G
    This is my off season favorite to plow the Judge through (Rough Go at Annadel in Santa Rosa, CA):
    Nice trail!

    DAN.GEROUS.NET : MOUNTAIN BIKING : CYCLOCROSS : ROAD :

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