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  1. #1
    mnt bike laws of physics
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    Help! Is my Lefty SL too short???

    I recently got a Lefty SL and after a 70 miler this weekend I noticed a topout thump so I reset the needle bearings. When measuring the length of the fully extended Lefty, with the damper way down inside the tube, it came out to be 657mm instead of the 695mm plus or minus 5mm. That is about 40mm too short
    When I reassembled it and measured it again it was 645mm instead of the 656mm shown in the setup guide. This is about a half an inch. My bottom bracket is already to freakin' low and I would rather it was long instead of short. What could be the problem?

    Thanks for your comments

  2. #2
    Ridin' dirty!
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    What parts of the fork did you take apart and re-assembled?
    "Common sense isn't always that common!"
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  3. #3
    I like to ride my bike.
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    After resetting the bearings, does it still top out?
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  4. #4
    mnt bike laws of physics
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    Quote Originally Posted by RideFaster
    After resetting the bearings, does it still top out?
    YES IT DOES!! I was pushing down pretty hard when I was resetting them and it did move a little but not much. The thing is almost new! only a few weeks old.

    I reset my lefty maxes all the time. One hardly ever needed to be reset and I had to slam it hard to get it back into place. The other moved very easily and had to be reset much more often.

    Do you think I need to slam it down harder. The manual says to gently do it...???

    Thanks for the inquiry.

  5. #5
    I like to ride my bike.
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    I'm no where near as good with this kind of thing as Mendon or Dan, but for me, I always have to use a ton of force to get any progress. Make sure all the air is out of the fork. It's a fully body workout and takes about 25-35 minutes to get it at 695 or 700. I've also found that 695 is not good enough, and it will only stop topping out at 700mm. I like to put the bike upside down, take off your shoes and hold the handlebars down with my foot and pull up with the wheel / lefty at full force.

    But, I'm sure if a Cannondale tech. saw this, they would strongly disagree with everything I just said. Ask Mendon or Dan before you try this at home...
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  6. #6
    mnt bike laws of physics
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    Well I slammed it this time and I was able to get it to extend to 700mm, but when I assemble it the measurement is still coming up 1/2 inch short. There may be variances in length, but 1/2 inch is more than I would expect.

  7. #7
    mnt bike laws of physics
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    Ride Faster...

    What does yours measure as per the setup guide - from the bottom of the leg to the bottom of the top cap?

  8. #8
    I like to ride my bike.
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    Quote Originally Posted by yogiprophet
    What does yours measure as per the setup guide - from the bottom of the leg to the bottom of the top cap?
    By this, do you mean, assembeled with air in the fork? If so, it is 665mm from the bottom of the fork to the top of the top cap. I have 65ish psi in the fork. No top out.
    Also, I've found it helps to put about 150 psi in before re-assembling it. It moves the damper up, without reducing the travel...although, I would assume you have figured that out already.
    Hope this helps.
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  9. #9
    I like to ride my bike.
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    Oh...the other thing it could be is you need to change your negative spring in accordance to you weight and psi set up. Too heavy a spring, too light a psi may be the culpret...although, again...run this by Dan or Mendon. You don't want to destroy a $1,000 fork...!!!
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  10. #10
    mnt bike laws of physics
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    Bonking ... not feelin' well

    I'm about 200 lbs. with gear and all and I put 130psi with the stiffest neg. spring.
    I checked my geometry and it was a half degree steep. I also checked my Prophet and it is dead on with the specs. If the Lefty SL was a bit longer, the angles would be where they are supposed to be and the bottom bracket would come up a hair which would be nice. I am loving the ride, but I find I am loosing momentum because I can't pedal through stuff I used to be able to. My poor pedals are getting tired of being beaten up.
    Mabey I just need to figure out how to ride through stuff more gracefully. With the Prophet, it was plain fun taking ridiculous lines. The Rush is a more serious race bike and I need to change my attitude when riding it.

  11. #11
    Kanonkuglen.dk
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    Same Problem Here... Help!

    I have extactly the same problem with my Lefty DLR2... when performing a bearing reset the fork reaches the specified 700mm, but when assembling the fork, it shrinks to only 625mm... and the manual says it should be around 656mm... thats about 30 mm off - and quite a lot!
    PLEASE HELP ME... whats the problem here? See the enclosed pictures...




  12. #12
    mnt bike laws of physics
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    Hello Lars

    Did you put air in it before measuring?
    I talked to the tech guy at CD and he said the 656mm length would only occur if the negative spring is fully compressed (i.e. if you could put enough air pressure in the lefty to compress the neg. spring fully - which would not be possible). That being the case, the manual is very misleading in my opinion, and should be changed.

    The question of why my geometry is not what it was intended to be could be that they measured it with no negative spring in the lefty
    I know a lot of people have complained about the bottom bracket being a little too low from what the team mechanic told me. BUT I have a fix. I put a Manitou Swinger in the rear. The Manitou shocks are always a little long and they require less sag(Ionly have 1/4" or 6mm sag) The damping is of much higher quality than the Fox. The rear end is almost exactly like my prophet now and I don't hit my pedals hardly at all(I did just put in on 2 days ago). The best thing of all is I don't loose momentum because the damper lets me sit and pedal over the rough stuff. AND it still accelerates like a rocket.

  13. #13
    Kanonkuglen.dk
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    Thanx for at quick reply:-)! When you say fully compressed... how many PSI should i put in the fork to get the full length when measuring?

  14. #14
    mnt bike laws of physics
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    Just put in the amount of air you need so that it feels right for you.
    Supposedly it will never reach the 656mm as in the setup guides picture as I described in the previous post.

  15. #15
    Kam
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    i have a 2005 speed carbon 110dlr2 sitting with extra parts right now....i kind of have the same problem...the fork sits too low. i bought the fork used and you can tell it hadn't been serviced recently.

    i did a bearing reset, cleaned and relubed some stuff and have a few rides on the fork...i love the feel. but, the fork is too low crown to axle...roughly 464mm. i should be getting 3" of travel (i am using it on a 29er) but i only have 2.75" of tire clearance from the lower steerer clamp.

    this also lowers my bb height abit too much for me. the fork should be sitting about 480mm (again, my fork is about 465mm).

    i think the problem is with the negative spring weight. i can extend my fork about 1" if pull on both ends.

    if you search "negative spring", you will find that the proper weight spring will bring you back to the correct fork length and the fork will perform better as well.

    the springs cost about $15 and the service is about $20 (a neg. spring swap will require special tools). i am 160 so i need a "standard" blue spring. unfortunately, i have no idea what is in the fork.

    check out this thread;
    Negative Spring Change In DLR2

    cheers!
    "forget kings...forget hadleys......they all have crap engagement. just run your bike fixed gear." - FoShizzle

  16. #16
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    Yep, the negative spring will reduce your lefty's length/travel unless you have sufficient air pressure to fully compress it.
    How much pressure depends on your negative spring stiffness.

    I have found that the amount of pressure needed to fully extend a lefty is more than recommended for use with any particular spring. eg. full extension on a red spring is 150psi minimum, but the pressure range recommended for a red spring is 125 to 140 psi.
    Similarly with the green spring (range 85 to 105 psi) 115psi is needed for full extension.

    As a result of this I run a lighter negative spring (green) than recommended for my weight (blue). Thus I get full extension and a more linear overall spring rate (which I prefer).

  17. #17
    Kam
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    Quote Originally Posted by GlenH
    Yep, the negative spring will reduce your lefty's length/travel unless you have sufficient air pressure to fully compress it.
    How much pressure depends on your negative spring stiffness.

    I have found that the amount of pressure needed to fully extend a lefty is more than recommended for use with any particular spring. eg. full extension on a red spring is 150psi minimum, but the pressure range recommended for a red spring is 125 to 140 psi.
    Similarly with the green spring (range 85 to 105 psi) 115psi is needed for full extension.

    As a result of this I run a lighter negative spring (green) than recommended for my weight (blue). Thus I get full extension and a more linear overall spring rate (which I prefer).

    right on, thanks!

    right after i posted my last message, i aired up my 110 dlr2 to 200psi (i only use 120psi for my 160 pound body and the max the fork can take is 225psi).

    with 200psi in the fork it is finally about 480mm crown to axle. so....i gotta go shopping for a neg spring and a shop to do the work. i think blue is recommended but i may go for a lighter green spring.

    thanks....this was a VERY helpful thread.
    "forget kings...forget hadleys......they all have crap engagement. just run your bike fixed gear." - FoShizzle

  18. #18
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    Good news Kam.

    One more thing you should be aware of:

    If your negative spring is too strong for your weight, then chances are your fork will be valved for a heavier rider too and therefore over-damped.

    C'dale spec leftys with damper valving and negative springs suitable for the weight of rider they expect, depending on frame size.
    ie. if you have a large frame, the fork will be set up for a fairly heavy rider (180-200 lbs). If (like me) you need a large frame, but only weigh 150-160lbs, then you should get the damper shim stacks changed to suit your weight as well as changing the negative spring.
    If you don't, the fork will feel good at a standstill and on small bumps, but will struggle with high speed hits (rocky stuff).

  19. #19
    Kam
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    thanks....i will have it re-valved.

    i live in los angeles, so i thnk it will be easy to find a shop to do this stuff....maybe helen's cycles.

    i am close to 6'1" and am 160 pounds. so, i am in the same boat as you. i would ride a c-dale xl frame.

    right now, i am riding a 2006 lefty carbon max spv (limited from 140 to 110). i have only one ride on it. that ride was horrible....i had to work on tuning the fork for my weight. tomorrow is another day and a long ride. hopefully everything feels better.

    i picked up my lefty speed for a song (relatively speaking) so i will keep her. it can find a home on my steel 29er ss.

    cheers!
    "forget kings...forget hadleys......they all have crap engagement. just run your bike fixed gear." - FoShizzle

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