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  1. #51
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    Have you changed cables?

    I find that Gore Ride-Ons cause me problems because they're so stiff. Because the front end is so light it doesn't take much to push-pull the Lefty around.
    and no, I am not missing the other half of my fork....

  2. #52
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    I find that my Lefty causes my bike to "corkscrew" whenever I jump it. Luckily, the Lefty's rigidity allows it to handle the awkward landings with aplomb . . .
    '95 M2 StumpJumper FS
    '11 Cannondale RZ 120-two

  3. #53
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    Quote Originally Posted by BoostN7 View Post
    Have you changed cables?

    I find that Gore Ride-Ons cause me problems because they're so stiff. Because the front end is so light it doesn't take much to push-pull the Lefty around.
    Yep , cables have been changed.
    More the fact that all cables now passes to left side of the frame so they all "push" the Lefty to the right.
    I'll experiement with cable lenght , I'll try to shorten them a bit.
    "There is a big difference between kneeling down and bending over" -FZ

  4. #54
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    It's funny. I rode with a CFR team member, and mentioned this thread. He proceeded to ride the first 3 miles of our single track with no hands...with a Lefty. I wish I could have taken video of it, but, I was laughing so hard (and quite amazed to be honest!).

  5. #55
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    Quote Originally Posted by fokof View Post
    Yep , cables have been changed.
    More the fact that all cables now passes to left side of the frame so they all "push" the Lefty to the right.
    I'll experiement with cable lenght , I'll try to shorten them a bit.
    That's exactly why! You should be routing all do the cables through the left side of the frame?

    I'll tell you what, I'll take a photo of my cabling tonight for you. It might not be the right way to do it but it works for me.

    Too long and you will get resistance when steering, too short and you can't steer at all. It's a fine line, and it's different for everyone (Different setups etc). My front mech cable is slightly too long at the moment, and I get a little bit of resistance from it. I'm hoping that when the cable "beds in" it'll be fine!
    and no, I am not missing the other half of my fork....

  6. #56
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    Okay, I've cropped this photo down a bit, it's not prefect but it should give you enough to work with.



    Firstly, please bare in mind that my cables are cross rooted on the down tube. That's how I've always done it, and how CSG usually do it. Also, sorry if my terminology is a bit off. I'm not a bike mechanic, just trying to help based from my own experience.

    The rear mech cable goes across the head tube and through the gap on the left between the frame and the lefty. When idle the cable should not touch the Lefty at all, only when turning right (sharply) should you get any sort of contact, and it should be minimal. You can use the rear brake cable as a guide and kind of sit the rear mech cable on top (depending on the rooting on the down tube.

    The front mech cable again goes across the head tube and over the top of the rear mech cable. I cut mine a little bit too long, which as I said above causes a little bit of resistance, but better to have too much than too little...

    Hope this helps. As I said, this might not be THE way to do it. But it works for me.

    Quote Originally Posted by 58teeth View Post
    It's funny. I rode with a CFR team member, and mentioned this thread. He proceeded to ride the first 3 miles of our single track with no hands...with a Lefty. I wish I could have taken video of it, but, I was laughing so hard (and quite amazed to be honest!).
    That's amazing haha, who was it? I was doing that last weekend, I got hit by a cross wind and almost crashed. That will teach me for being smug.
    and no, I am not missing the other half of my fork....

  7. #57
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    ... and if we just ...

    Quote Originally Posted by bee View Post
    Is it true that it is alot more difficult to ride no hands on a bike with a Cannondale Lefty fork? I've heard this rumor before that the bike pulls to one side, but wanted to see from people who have ridden these bikes. For those that don't know. The Lefty Fork is Cannondale's one-legged fork.

    I know it doesn't pull to the left riding no hands cause I do it all the time. But it definitely pulls left when doing mono's always always. For what it's worth I pull right when watching the Internet.

  8. #58
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    Quote Originally Posted by BoostN7 View Post

    Firstly, please bare in mind that my cables are cross rooted on the down tube. That's how I've always done it, and how CSG usually do it. Also, sorry if my terminology is a bit off. I'm not a bike mechanic, just trying to help based from my own experience.

    The rear mech cable goes across the head tube and through the gap on the left between the frame and the lefty. When idle the cable should not touch the Lefty at all, only when turning right (sharply) should you get any sort of contact, and it should be minimal. You can use the rear brake cable as a guide and kind of sit the rear mech cable on top (depending on the rooting on the down tube.

    The front mech cable again goes across the head tube and over the top of the rear mech cable. I cut mine a little bit too long, which as I said above causes a little bit of resistance, but better to have too much than too little...

    Hope this helps. As I said, this might not be THE way to do it. But it works for me.
    My setup is with a Rohloff , so both shifter cables passes alongside the downtube together (photo) so is the rear brake cable and , of course , the front.

    I have to experiement different length.
    Thanx anyways !!
    Attached Thumbnails Attached Thumbnails Riding no hands with a Cannondale Lefty Fork-dscn1380.jpg  

    "There is a big difference between kneeling down and bending over" -FZ

  9. #59
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    Well...

    Quote Originally Posted by amy_marc View Post
    Mine always goes right. Why?
    .
    .. it ain't the fork.

    ... in all seriousness....

    You probably have a wheel that isn't dished properly, or not fully seated in the dropouts, or maybe your frame is not perfectly straight. Yeah, it even happens sometimes with brand new frames.

    I sometimes get speed wobbles if I ride no-handed above 25 mph, but that's pretty much the only odd Lefty related behavior.
    Last edited by pimpbot; 12-05-2012 at 04:22 PM.

  10. #60
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    My lefty tends to cause my front wheel to feel unbalanced. Does anyone know the toe/camber/caster factory specs to resolve this? Also, can anyone explain why my tire loses some air over a months time with a lefty?

  11. #61
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    Quote Originally Posted by poorboy006 View Post
    My lefty tends to cause my front wheel to feel unbalanced. Does anyone know the toe/camber/caster factory specs to resolve this? Also, can anyone explain why my tire loses some air over a months time with a lefty?
    I run -2 camber with a smidge of toe-in for great cornering with tremendous stability. No-hands riding is rock solid in a straight line, and extreme no-hands lean angles are tolerated for hairpin turns with my hands firmly clasped behind my head.

    Did not know caster was adjustable on the Lefty?????

    Use anti-sieze on the axle nut to prevent the loss of air.
    '95 M2 StumpJumper FS
    '11 Cannondale RZ 120-two

  12. #62
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    It seems that my lefty likes to pull left no handed but when I ride home with a gallon of 1% in my right hand, stretched out I can ride straight. Just the other day I had to run to the store for 1/2 and 1/2 and didn't want to drive so i took my rush. TERRIBLE! Kept crossing the dotted line! I replaced my cables but the 1/2 and 1/2 still causes my lefty to pull left...? Should I just stick with whole grain wheat? I'm seriously thinking of switching back to my tried and true RS Judy.

  13. #63
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    I'm new to the Lefty, I've owned mine for only 2 months. I started reading this thread BEFORE I got my Lefty, but I'm positive it steers to the left going no-hands. I feel I have to compensate with body weight on the right.

  14. #64
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    I find it more difficult to balance. I've gone miles no handed but it's not as easy as some other forks.

  15. #65
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    29er Flash no problems with no hands
    Hi-mod Flash also no problems with no hands

    Amy hope you got your problem sorted, check your cable routing & dishing on this latter point here is a helpful video: How to Dish a Bicycle Wheel | TheBikeTube.com - YouTube

  16. #66
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    29er Flash no problems with no hands
    Hi-mod Flash also no problems with no hands

    Amy hope you got your problem sorted, check your cable routing & dishing on this latter point here is a helpful video: How to Dish a Bicycle Wheel | TheBikeTube.com - YouTube

  17. #67
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    Please don't hate for my resurrection of an old thread, but I'm baffled as to why no-one has done any basic maths on the matter. Some simple mathematical analysis could have done away with three pages of bantering, most of which was a competition for sarcasm (or lack thereof). The OP asked a legitimate question that can be analysed using some basic school science and mathematics.

    For now, let's ignore the rest of the bike, let's assume that the bike manufacturer has done all it can to have the most balanced bike possible with a traditional dual-legged fork. All else held constant, we can calculate the change in gravitational torque caused by swapping out say a 1650g traditional 100mm double fork (e.g. RockShox Reba), for a 100mm carbon lefty at around 1400g (just using round numbers).

    For this analysis, we consider the conventional fork as being made up of two forks, a left and right side, equidistant from the steerer tube, both weighing approx. 825g. The lefty is obviously treated as a single leg on the left side with mass 1400g.

    Lets also make the assumption that the radius r remains the same. Here, r is the distance from the centre of the rotation (which would lie somewhere on the steerer tube, going through centre and along the length of the bike) to the centre of mass of the fork leg. Even if r differed between the two models, I would imagine the difference to be absolutely negligible comapared to the mass shift.

    Let us now define our point of view. We will be looking at the fork 'from the cockpit', so that the lefty would indeed be on our left.

    Now, let it be very clear that a conventional fork would cause ZERO NET rotational torque. The left leg would cause a counter-clockwise gravitational torque, which would be equal and opposite to what is caused by the right leg. What does this mean? A conventional fork causes NO NET rotation either way. But that's obvious.

    What does the lefty do? Okay so we need to do some maths, but for those un-initiated in calculus, you can assume that the notation d(Q) represents "the change in Q", whatever Q is.

    Let T represent torque, g (a constant) acceleration due to gravity, F (also a constant) the force due to gravity, m (this changes) is mass of the leg, r (assumed above to also be approximately constant) is the radius as defined above. Then the net change in torque as viewed from the cockpit would be:

    d(T) = d(rF) = rd(F) = rd(mg) = d(m)(rg)

    So we see that ultimately the change in gravitational torque is proportional to the change in mass. The value of g on Earth is approx. 9.8m.s^2 (we'll be using SI units here) and using a crude measurement from my own bike I find that the value of r is approx. 65mm = 0.065m (again using SI units).

    The change in mass is interesting yet obvious when you think about it. Calculating d(m) is done using two parts: we find that we have a 825g LOSS due to the right leg 'disappearing' (by construction/design of the lefty), whilst we end up with a weight GAIN on the left leg equal to 1400g-825g=575g. Thus, adding these two figures together gives us a value for d(m) being 825g + 575g = 1400g = 1.4kg (SI), which is exactly the weight of the lefty.

    [Note: I could have bypassed all this calculation and just quoted the 1400g figure immediately, but I wanted to highlight how the left and right legs of the conventional fork effectively balanced each other out, just in case skeptics didn't believe my argument.]

    Plugging the numbers into the equation yields:

    d(T) = 1.40.0659.8 = 0.8918 N.m (Newton-meters, SI unit for torque).

    Let's convert this figure into the lovely imperial foot-pound unit for the sake of interpretation. Then d(T) = 0.66 ft.lbs (approx.)

    ***

    SUMMARY: the gravitational torque induced by a lefty can be simulated by placing a 250mL bottle of water (assuming the bottle itself weighs approximately 50g) on your handlebars, one foot to the left of your stem.

    In reality, if you did the above test, would you feel the front end of the bike tip to the left? It depends upon two things: your travelling speed and the mass of your bike. If you're going fast, the vastly stronger gyroscopic stability of the wheels will fight against any gravitational torque induced by the bottle. If you have a heavy bike, then the mass of the bottle is small in comparison to the mass of the bike itself.

    If you're travelling at say 30mph (keeping it imperial for you guys) on a 30 pound DH monster (not that you should fit a lefty to a DH monster, but I'm making a case here), almost definitely not. But the XC guys riding sub 20 pound lightweight machines, doing technical climbs and switchbacks at nearly walking pace, then not only does the bottle weigh potentially more than 3% of the bike's weight, there will be negligible gyroscopic stability to counteract this at those speeds.

    ***

    SUMMARY: changing a fork from a traditional dual-legged design to a lefty (something I'm doing on my Lapierre bike), DOES induce a NON-ZERO torque, which MAY be SLIGHTLY noticeable on lightweight (mine's around 22 pounds) at slow speeds (I do lots of XC climbs and switchbacks at near walking pace). The pulling effect due to the change in mass distribution of such a fork may be small but should not be automatically ruled out or neglected in certain circumstances.

    ***

    That being said, I wonder if the (equivalent of a) bottle of water on the handlebar's left side would only help to counteract the (equivalent(s) of) bottle(s) of water on the right side of the bike, namely the drivetrain components on the driveside of the bike? I personally suspect that all the stuff on the drive side (cassette, derailler(s), chain, chainrings) etc. may outweigh the stuff on the non-driveside (namely the brake discs and calipers)? If so, then I would assume that the weight re-distribution caused by the lefty (namely, moving 1400g to the left of the bike) would actually IMPROVE the balance of the bike, causing it to be LESS prone to 'pulling' to one side or the other. BUT, how balanced or unbalanced a bike is ultimately depends upon how balanced the bike manufacturer has got the rest of the bike, and that comes down to the individual frame geometries and material density distributions, i.e. another can of worms... so let's leave that technical analysis for another day!

    ***

    Sorry for the long post, but I hope it was (A) interesting (B) accurate/correct and most importantly (C) useful for readers and perhaps the OP!

    Happy grooving
    CURRENT BIKE

    Lapierre XR 529 e:i (2014) White/Black

  18. #68
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    Just hang bike from rear tire... Easier to visualize the offset mass effect that way.

    The precession is the hard one to demo... U addressed it nicely

  19. #69
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    Quote Originally Posted by rcko View Post
    Just hang bike from rear tire... Easier to visualize the offset mass effect that way.

    So riddle me this, given the torque resulting from the offset mass, what is it's gyroscopic effect? And how would it vary with wheel speed?
    G'day @rcko, firstly, hanging the bike from the rear tire would make it much harder (I imagine) to visualise the rotational torque due to the "offset mass", because (I think) this would be due to the much longer axis of symmetry (i.e. along the bike's length vs. along the bike's steering axis which is much shorter), but I could be wrong...

    Sorry, though I should have done enough physics to answer that question, I honestly don't know, perhaps someone else better versed can provide some insight?

    Nice things to consider though!
    CURRENT BIKE

    Lapierre XR 529 e:i (2014) White/Black

  20. #70
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    I think u did a pretty cool analytical approach. Bravo! Just figure, for some folks, hanging the bike from its rear wheel will help visualize the effect as well.

    The gyroscopics is what always gets my attention and how verse we become at unconscious motor muscle reflex to counter it.

    I just need 2 get out there and try riding my lefty no hands

  21. #71
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    Quote Originally Posted by rcko View Post
    Just figure, for some folks, hanging the bike from its rear wheel will help visualize the effect as well...
    ^^ this ^^

    Gives me an idea. Folks can hang their bikes from two points: the stem and the saddle. That should lead to the bike being able to be held balanced horizontally, simulating riding (albeit at zero speed ). Thus, if the bike tilts to the left, then it would undoubtedly visually indicate whether there is a virtual bottle of water sitting on their left handlebar!
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  22. #72
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    True! Worth testing.

    Thank for the explanation above.

  23. #73
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    Quote Originally Posted by rcko View Post
    True! Worth testing.

    Thank for the explanation above.
    You're welcome, and thanks for the kind compliments 😊

    Sent from my 0PJA10 using Tapatalk
    CURRENT BIKE

    Lapierre XR 529 e:i (2014) White/Black

  24. #74
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    Definitely an interesting read.

    Not sure why you bring up calculus, I understand you are calculating difference, but this is still seesaw-math.

    Also, if we want to do serious calculations here (assume we do as you seem to be very serious with that G 9.8 instead of just going with 10...) why do we not look at the entire system, including the rider?

    A 75 kg rider would have to move his body exactly 0.89/(75*9.8)=1.2 mm to the right to counteract the torque from the Lefty, assuming the human body is balanced with the organs nicely arranged.

  25. #75
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    Quote Originally Posted by pvajko View Post
    Not sure why you bring up calculus...
    Touch, agreed, apologies. Indeed you need not deal with infinitesimals, but rather just ordinary 'changes'. I was just lazy and couldn't be bothered copy-pasting the Delta (Δ) symbol every time, so I just decided to use 'd' instead
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