[Nizmeister]

Anyone seen this already?

New on the Cannondale Scalpel 3000

"What’s most notable about the weight loss found on the current Lefty is that the unsprung weight has been trimmed significantly. Unsprung weight is the mass of the fork located beneath the shock cartridge. By combining a carbon and titanium structure in the lower leg of the fork, Cannondale’s engineers altered the unsprung weight for radically better small bump response. "

I saw a chap this morning getting of a train as I was getting on. I immediately did a search when I gto to work!

I thought that he had done a home mod.

 

[sub6]

Uh, Niz, you been under a rock? They've been out for a couple of years now, I see 'em everywhere. I guess not to common in your neck of the woods, eh?

 

[binary visions]

Actually, they're not common in THIS neck of the woods, either, but indeed they have been out for quite a while =)

Pretty weird if you ask me; I wouldn't use one. I don't care if they work worse, the same, or better, it's just too much of an oddity for me... It'd make me think I was unbalanced.

 

[Carbon Fetish]

Originally posted by binary visions
...It'd make me think I was unbalanced.

Well your driveterrain is on the other side so would that balance things out? hehe Sorry, being a smartass. I thought about that when I first read out the new Specialized FSXC Epic frame with the shock on the left side of the bike and then I went "DOH!"

 

[Rodger]

Originally posted by binary visions

Pretty weird if you ask me; I wouldn't use one. I don't care if they work worse, the same, or better, it's just too much of an oddity for me... It'd make me think I was unbalanced.

Weird indeedy, I've been riding a Cannondale with Lefty,
every time I looked down I thought I was missing something.
But the thing simply works as any other fork, working
pretty good I must say. But hey, I am a Marzocchi-freak, so
I just stick to that.

 

[binary visions]

Originally posted by Carbon Fetish


Well your driveterrain is on the other side so would that balance things out? hehe Sorry, being a smartass. I thought about that when I first read out the new Specialized FSXC Epic frame with the shock on the left side of the bike and then I went "DOH!"

Heh, actually the Epic shock doesn't bother me because the frame is balanced.. It's the thought of structural components being one sided that bugs me. I mean, would you beef up the left side chainstay and get ride of the right hand one? It'd eliminate chainslap! Just too strange.. It may work but I think Cannondale went a little too far with their propriatary crap with this.. People complain about inverted forks being torsionally flexy.. How torsionally flexy is a SINGLE SIDED fork going to be?

Oh well. I enjoy a nice looking bike that turns heads, but I don't want it to look like a freak show. Besides, if your bike doesn't inspire confidence, you won't try harder things, and seeing that one side of my fork is missing doesn't do that for me.

 

[Phreaddy]

Originally posted by binary visions


I think Cannondale went a little too far with their propriatary crap with this..

Uhh, every single automobile has its wheels mounted only on one side.

 

[binary visions]

Originally posted by Phreaddy


Uhh, every single automobile has its wheels mounted only on one side.

Yeah, but we're talking about a 4 or 5 or more bolt mounting pattern, on a wheel that is 4+ inches wide, made of cast steel or aluminum; not a CNC'd aluminum hub with a hollow, sub 20mm axle running through it. Even when car wheels were still using spokes there were a whole lot more of them and they were 3 times as thick. Not to mention the hub of the wheel is proportionally a lot bigger than on a mountain bike. It's definitly not even remotely the same thing.

And when was the last time you saw a car wheel mounted on an aluminum, air sprung shock that's a foot and a half long by, what, maybe an inch and a half in diameter, with no other structural support to hold it in place? Or saw one with only one shock in the front (instead of two to spread the impact out)?

 

[Phreaddy]

Virtually every point you bring up can be attributed to the huge weight, speed, and thus load-bearing-force differences between a car and a bike. As for the shocks, well, a car usually has one shock per wheel -- just like the Lefty.

 

[ohio]

Check the rear swingarm on a ducati 916/998. Single sided structures for the same weight are about equal in stiffness torsionally, and stiffer than double sided structures in every other aspect except camber (theoretically... it's pretty hard to compare the two directly since so many components change between the two).

 

[binary visions]

*shrug* Perhaps I'm just a little anal about things like that. I want my parts to be symmetrical. You have to admit, the confidence your bike instills in you, real or imagined, is often just as important as the actual strength of the bike. I rode a bike for the past two years that I've been afraid to push to it's limits because I have no confidence in it. I'm always sure it'll break off the next jump.

My comment about Cannondale going too far with their propriatary crap is related to the fact that if you buy a Lefty, you have to have the Cannondale sized headtube, the special Cannondale Lefty hub, with the specific Cannondale Lefty axle. Me, I like options. So, what, Phil Wood makes a Lefty hub, right? You can choose from TWO front hubs? One of those better be the quality, price, and color you want because there's no other choices.

Anyway, I'm not saying the Lefty is a bad fork. I'm saying I don't like it. Boils down to my personal preference. So... :eviltongu

I'd like to see some actual data on the fork though if anyone has it.. Strength, deflection, dimensions, etc.

 

[ohio]

Originally posted by binary visions


My comment about Cannondale going too far with their propriatary crap is related to the fact that if you buy a Lefty, you have to have the Cannondale sized headtube, the special Cannondale Lefty hub, with the specific Cannondale Lefty axle.

I'd like to see some actual data on the fork though if anyone has it.. Strength, deflection, dimensions, etc.

I'll definitely agree with you on the first point.

On the second, I remember seeing a Cannondale comparison of torsional stiffness (no mention of lateral or fore-aft) from like 3 or 4 years ago that had the Moto120 at the top, but the Lefty above pretty much every other fork on the market uncluding dual crowns... Could have been BS though since it was a Cannondale in-house test...

 

[RideMonkey]

I think this is one case where having the pros ride the stuff says it all.

If Cedric can race Slalom and MTN Cross, and can dirt jump on a lefty, then its gonna hold up under normal use.

You can show me all the FEA and computer simulations in the worls, but I'd rather see Cedric going big.

 

[crashing_sux]

Single sided structures actually need to be heavier to achieve the same weight and stiffness as double sided structures. That's why Ducati finally switched to a conventional double sided swingarm on their 916/998 replacement which just came out this year, the 999. It's also why every other racing street or dirt bike that you can buy uses a double sided swingarm. Ducati was never under the impression that a single-sided was as light and stiff as a conventional swingarm, they only used it because it looks so damn good. Face it, ducati's are sexy bikes, that's why most folks buy them.

As for the lefty though it could potentially have one huge advantage over a conventional suspension fork that would result in improved suspension action and lower weight, reduced stiction. Conventional suspension forks add a lot of weight trying to be extremely stiff because the slightest amount of uneven movement in the fork legs results in huge amounts of stiction in the fork seals making the suspension action feel terrible, especially on small bumps.

Whether or not the potential advantage the Lefty has is ever realized is up to the engineers at Canondale, but hopefully everyone here won't be so stupid as to assume the design is flawed just because it doesn't feel as good as your favorite fork, be it fox, zokes, or whatever. That would be just as bad as riding a huffy from your local department store with a piece of crap conventional fork design and saying that conventional designs sucked....that just doesn't tell the whole story.

- Shane

Originally posted by ohio
Check the rear swingarm on a ducati 916/998. Single sided structures for the same weight are about equal in stiffness torsionally, and stiffer than double sided structures in every other aspect except camber (theoretically... it's pretty hard to compare the two directly since so many components change between the two).

 

[ohio]

Originally posted by crashing_sux
Single sided structures actually need to be heavier to achieve the same weight and stiffness as double sided structures. That's why Ducati finally switched to a conventional double sided swingarm on their 916/998 replacement which just came out this year, the 999. It's also why every other racing street or dirt bike that you can buy uses a double sided swingarm. Ducati was never under the impression that a single-sided was as light and stiff as a conventional swingarm, they only used it because it looks so damn good. Face it, ducati's are sexy bikes, that's why most folks buy them.

Actually Ducati went to a double sided swingarm because a double sided swingarm maintains camber better (something I noted above) and lateral flexibility can be designed in without having to worry about the frame tracking straight.

Really comparing the lefty to a double-sided is not a direct comparison since the double sided forks have freely rotating round stanchions, and torsional stiffness is defined by the BENDING stiffness of the outers and stanchions, whereas the lefty uses a square stanchion and it's stiffness is defined purely by the torsional stiffness of that single memeber and the needle bearings it rolls against.

I think it's great fork
, and it's problems with incompatibility will greatly be reduced as other manufacturers (both frame and fork) release 1.5" products... The hub is still an issue, but it's pretty hard to make a bad front hub, and many people sell their 20mm hubs with their 20mm forks, so this is not much different.

 

[Will_Jekyll]

The lefty can fit any standard mtb it is not limited to 1.5 head tubes. It's just costs to much to be a realistic upgrade.

 

[crashing_sux]

I caught that you noted a double-sided swingarm maintains camber better. I thought that was just an example you were using of the problem with single sided swingarms and stiffness. I must have misunderstood you. How exactly is the camber changing without flexion of the swingarm, and how is the double going to "maintain" the camber better without being more resistant to flex? I was equating "maintain" to "stay the same" and thinking that anything that wasn't staying the same shape was flexing. I'd love to hear more about how that works.

By the facts you are throwing out it sounds like you have access to some pretty good Ducati technical documents, do they happen to be posted on the web? I'd love to read through them, love the fast bikes. I've just been going by what my local Ducati shop tells me and quotes like these...


"The Italian firm has also ditched its trademark single-sided swingarm for a more conventional double-sided unit in order to save weight and for greater stiffness." at http://www.cbrworld.net/news/news_detail.asp?IDNews=119

and "Ducati has also ditched its trademark single-sided swingarm for a more conventional double-sided unit in order to save weight and add stiffness. " at http://www.micapeak.com/


and "A single-sided swingarm, associated for so long with the 916, has been ditched in favour of a more traditional dual-sided design.

The firm persisted with the single-sided approach long after most teams accepted that a dual-sider was better. Normal swingarms are lighter and less prone to twisting than the chunkier single-siders, and give better feedback to the rider. But for Ducati the double-sided swingarm was plain ugly. " at http://www.motorcyclenews.com/news/detail?sectionID=50678&documentID=139549&pageNum=2

Don't get me wrong, I love the idea of the lefty, I just don't agree with you on the lightness vs. stiffness issue with regards to single sided or dual sided swingarms and your using Ducati as an example when the majority of the racing world has known for some time that this is not the best route to take, and that right or wrong Ducati makes beautiful motorcycles first, fast bikes second. Even now they are currently playing with 4 different fairing designs, they allready know which one is the most aerodynamic but their is a constant battle between the engineers wanting it to be fast and the sales guys wanting it to be pretty.

I'm not sure what your definition of camber is either. As I know the term it refers to the angle of the tire in regard to the surface it is riding on, or the difference between the distance between the top of the tires and the bottom of the tires on vehicles like cars that have two tires side by side.

In respect to a motorcycle the only variance of camber in relation to the swingarm is through flex, which was my issue with it in the first place, for the same weight, they flex too much.

- Shane

Originally posted by ohio


Actually Ducati went to a double sided swingarm because a double sided swingarm maintains camber better (something I noted above) and lateral flexibility can be designed in without having to worry about the frame tracking straight.

Really comparing the lefty to a double-sided is not a direct comparison since the double sided forks have freely rotating round stanchions, and torsional stiffness is defined by the BENDING stiffness of the outers and stanchions, whereas the lefty uses a square stanchion and it's stiffness is defined purely by the torsional stiffness of that single memeber and the needle bearings it rolls against.

I think it's great fork
, and it's problems with incompatibility will greatly be reduced as other manufacturers (both frame and fork) release 1.5" products... The hub is still an issue, but it's pretty hard to make a bad front hub, and many people sell their 20mm hubs with their 20mm forks, so this is not much different.

 

[ohio]

No special access to ducati documents, just spent a lot of time reading books on motorcycle chassis design while working on my bike designs. You're right about camber. Camber as it applies to forks is actually analogous to yaw or steer when speaking of a swingarm. I just continued to call it camber for the sake of continuity. Yaw is the angle difference between the centerline of the rear wheel and the centerline of the chassis when viewed from above. Lateral flex is the distance the the rear axle is offset from the centerline of the chassis. Under zero stress both of these figures are zero. I hope that makes sense.

Assuming a single-sided and double sided swingarm of equal weight and the same forces, the single-sided swingarm is stiffer vertically (compression of the damper), much stiffer laterally, equal to slightly stiffer in actual camber (angle of rear hub vs. horizontal when veiwed from the back of the bike), but will show a significantly greater change in yaw vs. a double sided.

So a double sided swingarm offsets lateraly but keeps the wheel inline with the centerline. Since motocycles need to flex laterally to absorb vertical bumps while cornering, but don't want to change yaw as that changes the direction the motorcycle is tracking, a double sided swingarm is ideal, especially for road racing when lean angles approach the ridiculous.

In the days when it was thought that the stiffer the chassis the better, a single sided swingarm was a great idea. Now that "tuned" flex is beng better realized as a tool for good handling in corners, a double sided swingarm is preferable.

edit: another major reason ducati used the single-sided swingarm was for fast wheel changes, which doesn't really apply to this so much...

 

[crashing_sux]

Mentally replacing the word camber with yaw.....Now I'm following you.

God I love this stuff

 

[JMAC]

Ok you monkeys i ride a Lefty and it can handle alot it's very stiff and in my opinion the best fork ever made i've ridding loads of forks but this is the best.