Zero G Boxer Squad

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mises
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by mises

Interesting pictures. I thought sharp edges in machined metal were supposed to be stress risers.

stumpytrunks
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by stumpytrunks

I'd like to congratulate Ted for doing it right. No use bringing something onto the market that isn't ready. Better to be complaining about them being late than complaining about the injuries you might have sustained if they failed. Looks like the black and white photos were due to the cranks not being anodized yet.

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C a s r a n
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by C a s r a n

Lord Vader wrote:C'mon Ted, make the cranks 100g heavier and release them. I don't want them because they'r light but because they look so beautiful



Hmmm... the brand is Zero Gravity, not "Feel the Gravity", Lord Vader. 8)


Those few pictures look great again. Can't wait for my crankset to arrive. Meanwhile Zero Gravity got some nice coverage for their crankset in magazines, but still do not have it on the market... rather a pity, but that will all be forgotten if we'll have it on the bike, isn't it?
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spookyload
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by spookyload

Don't bash guys for having fun at Zero Gravity's expense. The company owes them nothing, and they owe the company nothing. I realize some of you will be getting a free set and are trying to keep your attitude positive because of it, but don't deprive a person a little fun because of your agenda. It is almost comical the way some of you defend the crank design. He has a product that is years behind schedule. He "wants to get it right?" Correct me if I am wrong, but he is doing simple CNC work to aluminum to make a bike go forward, not trying to discover a way to make cold fusion or some other highly complex molecular process happen. It isn't rocket science. I don't even want to think how much revenue he has lost with the delay of the release. Not to mention the bad press he is getting as a result of revealing them at Interbike 1992(he he he) and then not producing them for years later.

alienator
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by alienator

mises wrote:Interesting pictures. I thought sharp edges in machined metal were supposed to be stress risers.


They can be, but if the level of that stress is so low it's inconsequential, then I suppose fashion can prevail.

Really, it's not useful to talk about a stress riser without talking about in context with design parameters, material, test results, and etc.

FWIW, I think the new ZG design looks hideous.

alienator
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by alienator

spookyload wrote:Don't bash guys for having fun at Zero Gravity's expense. The company owes them nothing, and they owe the company nothing. I realize some of you will be getting a free set and are trying to keep your attitude positive because of it, but don't deprive a person a little fun because of your agenda. It is almost comical the way some of you defend the crank design. He has a product that is years behind schedule. He "wants to get it right?" Correct me if I am wrong, but he is doing simple CNC work to aluminum to make a bike go forward, not trying to discover a way to make cold fusion or some other highly complex molecular process happen. It isn't rocket science. I don't even want to think how much revenue he has lost with the delay of the release. Not to mention the bad press he is getting as a result of revealing them at Interbike 1992(he he he) and then not producing them for years later.


I think you've over simplified things by a lot. Yeah, there is a product that will be CNC's. However, in the time between when that product was designed and today, the designer left, the factory was moved, and who knows what else has happened. None of us sit in on their company meetings.

The idea that just because a crank only makes a bike go forward means that you should be able to produce one just by flipping a switch.....well, that's bollocks. By the same thinking, Shimano and Campy should have had their electric versions ready years ago; SRAM should have only taken a couple of weeks to design the relatively few, simple parts that make up brifters, derailleurs and the rest of the lot; and no bike manufacturer should have to spend any time at all doing testing.

I'm also sure that ZG never considered, at all, any of the other crank failures there have been with lightweight cranks: Pulsions, Time cranks, Propellors and similar cranks.......nah. Not worthy of nary a concern.

Heck, it's likely that ZG and the related company only work on the brakes and the cranks, so they've got all the time in the world. :roll:

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ebsilon
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by ebsilon

The new ZG-crank looks fine indeed – but from at mechanical designer’s point of view I do not think they have come up with the right design that is ZG worthy.

It sems like ZG is stucked in the early '90. Look at the inside of the arm. Com'on - it is like they are desperate to loose weight so they have drilled a lot of holes. They can never achieve a crank that can beat FSA, Campag or DA by the use of small holes

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Is that the way to go?

Look at campagnolo or FSA.

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Or Cannondale SI og Dura Ace for that matter. That is the way to go.

And no, I don't have a problem with ZG - I think that their brakes are the best - period.

Kuiper
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by Kuiper

The design of the Zero Gravity is much stronger,
since the others like Dura Ace / FSA are hollow they will bend or failure earlier and is less stronger then the ZG design.
And I wonder in how far customers can use the warranty,
my left arm had already been replaced without problem at Shimano Germany,
and now I got a issue right crank at the places where you mount the bolts of your chainring which is bended during normall use.
(it only got 500km, 269 euro's) and has been sended to Shimano Benelux and they're going to do nothing with it.

ZeroG wrote:A lot of you are opting for the Heavyweight Boxer; there will be a laser mark that will say Heavyweight but I was thinking of replacing that with "Bigfellow" in honor of Bill, just on the tester's cranks for whom it will mean something.

Hope that this will be also on it like Ted is saying.

Alfie
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by Alfie

Kuiper wrote:The design of the Zero Gravity is much stronger


Why is your frame hollow? :lol:

The reason why ZG cranks have holes in it instead of being hollow is because they are CNC machined. Campa and Shimano cranks are forged.
It has nothing to do with being stronger but with the productionmethod.

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Timo
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by Timo

Kuiper wrote:The design of the Zero Gravity is much stronger,
since the others like Dura Ace / FSA are hollow they will bend or failure earlier and is less stronger then the ZG design.

Since when are you such an expert? Are you an engineer? Have you even seen the 0G cranks, let alone used them? On what do you base your conclusions? :?
And if I ever meet an aardvark, I'm going to step on its damn protruding nasal implement until it couldn't suck up an insect if its life depended on it.

Kuiper
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by Kuiper

Timo wrote:Since when are you such an expert? Are you an engineer? Have you even seen the 0G cranks, let alone used them? On what do you base your conclusions? :?


Speaking with Chinese Engineers :wink:
and seeing several failures at the dura ace crank like zagorski and mine.
The Zero Gravity design seems so much stronger in my eyes, since it's not hollow as one picture just drills.
The walls of the Dura ace cranks are very thin, have seen it by myself.

Edit: just to make it more clear, I just think the ZG should be stronger then the Hollow cranks.
Cause it got stuff on inside to protect the outher wall, (if it ever crash or something I think it hold it longer in-tact)
Last edited by Kuiper on Tue Apr 03, 2007 2:27 pm, edited 2 times in total.

NS
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by NS

Thats 2 failures you have seen in how many units?

A machining/forging is only as strong as it is designed to be, unless you have access to the material properties and models of both sets of cranks how can you make this judgement.

The failures you have described are more than likely down to impurities in the alloy of the crank or some other stress riser. If zero gravity shifted as many units as Shimano Dura Ace then they might find they had to contest with people who have seen 2 such examples in X hundred thousand units criticising their product on a web forum.

As they are going to move a lot less units theres a lot less chance of seeing breakages

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ebsilon
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by ebsilon

Kuiper wrote:The design of the Zero Gravity is much stronger,
since the others like Dura Ace / FSA are hollow they will bend or failure earlier and is less stronger then the ZG design.


Please Kuiper, save your statemant - you might disprove it when you are going to study sometime. If you are going to study engineering some day, then you will see that you was wrong. It is a shame that you don't live next dors to me, because then I could have shown you a FEA (finite element analysis) of a part constructed the same way like ZG and a hollow part like DA, Record ect.

Ciao ebsilon

mrfish
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by mrfish

The easiest illustration of why the Campag/ FSA / Shimano cranks will always be superior to a CNCed part is something you can try yourself sometime using a piece of cardboard such as a toilet roll.

1. See how strong the toilet roll is in torsion with your hands
2. Make one cut along the toilet roll so that its section is a c rather than an o
3. Now test how strong it is in torsion. You will be surprised at the difference.

Why is this relevant to cranks? Basically the Campag / Dura Ace solution builds a closed shape whereas the relieved CNC shape is an open shape. For torsional loads such as those experienced by a crank, the closed shape is always more efficient.

Next question is what you do to take the bending load - this modifies the circle to give an ovoid or squareoval similar to that used by the forementioned manufacturers. This is why the hollow rather than sideways CNC'd option will always be more efficient.

If you wanted to build efficient CNC-machined cranks, you would either glue them together like the Cannondale Hollowgrams or drill down the length of the crank like the latest Rotor cranks or Caramba double barrels (remember them?) and plug the end. In my view relieving / milling holes is just for show.

by Weenie


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GonaSovereign
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by GonaSovereign

Kuiper wrote:I just think the ZG should be stronger then the Hollow cranks.
Cause it got stuff on inside to protect the outher wall, (if it ever crash or something I think it hold it longer in-tact)


An engineer or industrial design person will tell you the material in the middle of a crank adds very little strength to a tubular structure. Bike frames are made out of tubes for a reason. A solid tube would be somewhat stronger but significantly heavier. As far as cranks go, Bullseye, Sweet Wings and a couple others were ahead of the game in terms of design (if not always perfect execution). The reason more companies don’t build cranks like Dura Ace is because it is difficult and expensive to forge a channel shape, weld a plate to close it, finish it, etc.

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