Cannondale Lefty vs Conventional Fork

[Anthony]

bet it's quicker to change a tube on a loose wheel than one that is attached to a bike...

[Tumbleweed]

bet it's quicker to change a tube on a loose wheel than one that is attached to a bike...

 

 

 

why?

[ASTANA]

Its simple actually. Mostly Cannondale people like it, others like me think its weird.

[Red Zone]

I have heard from a shock mechanic that the lefty is a real bugger to work on and needs more regular servicing than other conventional forks, so it is more expensive in the long run, that being said, when well maintained and properly set up it is meant to be pretty great. Once again the age old cycling adage applies, light, strong, cheep, pick any two.

[Johan Bornman]

Cut cut cut cut

 

Its a lot stiffer than any other fork in resistance to twist which makes the steering very quick. Cannondale tame this slightly by providing their bikes with a slightly slacker head angle.

 

Hmmmmmmmm....I'm not convinced, Lefty.

 

I see this often but I wonder if any of those marketing people have actually bothered to think how much torque is required to steer a bike? Zero (or 000000.1NM), I think. A bike can be steered just riding no-hands, which definitely transmits no torque down the handlebars.

 

Further, a bike steers pretty well with a loose stem (ask me, I have done it) and when the stem eventually does swivel completely freely, it is because of a bump in the road and not from steering.

 

I agree that a thicker steerer has more resistance to torque, but I argue that the increased stiffness is only really used in the fore-aft vibration of the fork rather than in steering.

 

 

I also cannot envisage a forceful steering event where torque would be required.

 

 

Edit: My decimal is in the wrong place, but read what I mean, not what I write.

 

Johan Bornman2009-05-28 09:20:54

[Tumbleweed]

Cut cut cut cut

 

?

 

Its a lot stiffer than any other fork in resistance to twist which makes the steering very quick. Cannondale tame this slightly by providing their bikes with a slightly slacker head angle.

 

?

 

Hmmmmmmmm....I'm not convinced' date=' Lefty.

 

?

 

I see this often but I wonder if any of those marketing people have actually bothered to think how much torque is required to steer a bike? Zero (or 000000.1NM), I think. A bike can be steered just riding no-hands, which definitely transmits no torque down the handlebars.

 

?

 

Further, a bike steers pretty well with a loose stem (ask me, I have done it) and when the stem eventually does swivel completely freely, it is because of a bump in the road and not from steering.

 

?

 

I agree that a thicker steerer has more resistance to torque, but I argue that the increased stiffness is only really used in the fore-aft vibration of the fork rather than in steering.

 

?

 

?

 

I also cannot envisage a forceful steering event where torque would be required.

 

?

 

?

 

Edit: My decimal is in the wrong place, but read what I mean, not what I write.

 

?

[/quote']

 

 

 

johan, i know you don't like the pr bumpf, but the stuff on the lefty and the headshok is worth a read...

 

 

 

...as is this product review...http://www.mountainbikemilitia.com/stuff/headshok.html

[WillemT]

there's no torque needed when steering a bike on a flat tar road, that might be so, but if to go down a single track there's definitly a lot of torque present. If you ride of a side walk at a very very slow speed at a 45 deg angle, at the point where the front wheel goes off you'll feel that the handle bars want to turn. Same happens on single tracks when going over rocks etc...

 

So there's your event where you need torque and where a stiffer fork will give you more precise steering...

[Johan Bornman]

there's no torque needed when steering a bike on a flat tar road' date=' that might be so, but if to go down a single track there's definitly a lot of torque present. If you ride of a side walk at a very very slow speed at a 45 deg angle, at the point where the front wheel goes off you'll feel that the handle bars want to turn. Same happens on single tracks when going over rocks etc...

 

So there's your event where you need torque and where a stiffer fork will give you more precise steering...

[/quote']

 

 

I can see that there is some torque in that scenario, but  now we've just moved the decimal a few places to the left. Still not enough to warrant a thicker steerer for steering (not fore-aft) purposes.

 

Try this little experiment. Pull your bike up onto its back wheel and hold the rear brake. Ask your strong friend to yank on the front wheel to the left and right and resist that movement through the bars. Tell me if you've ever experienced such forces whilst riding. If you have, you have the scars to show for it.

 

Secondly, you'll notice that the steerer is far stiffer than the wheel and handlebars. No use putting a drainpipe in there if you are transmiting the torque through a spoked wheel and resisting it at the other end with a little handlebar.

 

I think Cannondale post-rationalised their bigger steerer and came up with some valid reasons and one invalid one.

 

 

Postscript: I disagree that there is torque present when steering through a slalom singletrack. If it is bermed, absolutely zero torque and if it is not bermed, then it can be ridden no-hands (if you can displace your body fast enough to make the corner). Steering quickly at most requires torque to overcome the lateral inertia of the front wheel, which is close to my definition of zero.

 

Johan Bornman2009-05-28 09:43:03

[Johan Bornman]

johan' date=' i know you don't like the pr bumpf, but the stuff on the lefty and the headshok is worth a read...

...as is this product review...http://www.mountainbikemilitia.com/stuff/headshok.html[/quote']

 

 

Haleuia!!!( how the hell do you spell hale...whatever?)

 

For the first time EVER I've read a bicycle review where they've used proper science. None of this "I can feel it in my pants that this things rolls faster than that thing" nonsense.

 

Good stuff. I hope Cannondale takes note.

[WillemT]

Ok I think I misunderstood a little...

The larger diameter steerer is not what makes the fork stiffer according to me. As I think the larger steer was just to make space in the steerer tube for the headshok's internals wich were developed first before the lefty.

The fact that it has a 8 sided internal steerer with 4 sides running on bearings is what makes it a lot stiffer as there is no way you'll get any rotational play between those surfaces.

 

On a convetional fork, your surfaces that slides on each other is round and although there is two of them there is no or very little rotational resistance them individual, it's the fact that there's 2 of them that puts a constraint on the rotational movement but you still get some rotational play. This can easily be seen if you take a old fork with small diameter stanchions and compare it to a newer fork with much larger diameter stanchions. The larger diameter doesn't bend that much and therefore the whole frame of the shock is stiffer and that in turn limits the rotational play or rotational flexibility rather, on the fork.

[WillemT]

that must have been the most useless review i've ever read in my life!!!

[Johan Bornman]

The rotational play on a conventional fork is from bending forces in the individual legs, not torsional forces. Its a little bit confusing I suppose, a bit like the force that compresses a coil spring, it is not bending but torsion.

 

Anyway, I have never ridden a Lefty or tried to yank the front wheel around so I can't say it is stiffer or not. I just think the supposed increase in torsional stiffness in the steerer is waste or as Holy puts it, PR bumph.

 

 

[Johan Bornman]

that must have been the most useless review i've ever read in my life!!!

 

Nonsense!   It sets out to disprove a marketing claim and they did, with flying colours.  In my library with the porcelain throne I have four MTB mags donated to me my Dirtbreath. They're full of reviews and not one uses such great and exact techniques as this review. I think you need to rethink your flawed position on this one.

[WillemT]

well to shoot on a fork is a useless test to me for knowing how good the fork is. I mean it's a mtb sus fork not a bomb shelter. Would cannondale literaly mean that it's bullet proof? I don't think so.

[GoLefty!!]

Ok there's a little misunderstanding going on and I take some responsibility for that. When I say there's less torque I don' tmean on the steerer of the fork, I refer to the twist in the fork from the riders weight, spinning wheel.

 

With a two legged fork you have those legs held together by a spindly brace across the top. These braces take quite a large amount of force (rider weight and dynamic forces on the bike). In some forks, where there has been a manufacturing problem these braces have broken.

 

With the Lefty, the large diameter LEG of the fork resists twist due to it's section. The lower end of the Lefty is held in place by 4 needle bearings on races sets which keeps the lower end very resistant to twist (torque) as well. The set up is noticably more resistant to twist than say a Fox F100RLC.

Its this twist that can be felt through the bars and its this I refer to when I  say "Quicker or more direct steering".

Another stiffness advantage Lefty has is due to the stub axle being a 20mm cantilever. Thats a far stiffer in bending connection than any 9mm QR axle which is often not properly clamped anyway. Some trail forks now approach the stiffness of Lefty but those weigh nearly 2Kg..

 

Now a Headshok, Theres a product that I have great affection for. I had a DL80 and DL70 for quite a while, overlapping my time with lefty. The Headshol for me was always better than Lefty because it looked more weird and it tracked extremely well. The 80mm versions are brillaint for hardtails but sadly there is no 100mm Fatty. If there was It would be on my bike.

 

In terms of maintenance, a mechanic who says that it's more maintenance intensive has either;

 

- never worked on one and is talking out of his/her arse

- is not very competant with mechanical things.I think we agree that this is undesirable in a mechanic.

- has a built in fear of things that are different. Probably also a homophobe and drinks Lion.

 

I have stripped Headshok Fatty and Lefty and assembled them without any parts remaining on the workbench many times. None has fallen apart (testimony to the fact that the riders still have their front teeth).

 

I agree Lefty looks weird and too some thats reason enough to be sceptical. However, weird grows on you, some of my best friends are weird. Weird often rewards with reliability and easy relationships.

 

 

Now cue the guy who has a friend whose cousins sisters boyfriend's father in laws son's girlfriends, bosses nephew had a Lefty and it gave him extraordinary trouble.

Well getover it, everything has a "made on a friday" including boring Toyota's. There are plenty out there which are made on other days and have been functioning like a swiss clock for the last 10yrs.

 

[WillemT]

from a co dale rider, well said!!