Zero G Boxer Squad

Discuss light weight issues concerning road bikes & parts.
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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.

by Weenie


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.

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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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drjones96
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by drjones96

We don't know nuthin' until these cranks get out there!

mises
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by mises

mrfish wrote: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.
M5 also glued theirs together in the prototypes, though the production ones will be laser welded.

I think there are tradeoffs whatever way you go and as with all design you have to choose which factors are most important to you in coming up with the final product. Sweetwings pretty clearly chose weight above all else, the rest aren't so easy to tell which criteria were given the most importance.

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Timo
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by Timo

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

Kuiper wrote:The Zero Gravity design seems so much stronger in my eyes

That's quite a difference. But I do like your comment about Chinese engineers. I understand that you're fluent in Chinese and a frequent visitor of their facilities? 8)

As for your comment on hollow structures vs. solid ones. Is your Canyon frame made out of solid tubes? No? Well, do you still trust your frame or will you swap it for a Chinese frame with solid tubing?
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.

Auk
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by Auk

Kuiper is a riddle. Only he knows the answer.

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C a s r a n
WW of the Year 2005
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by C a s r a n

mike wrote:i think Ted will stay true to his word. all of us probably have at least 1-2 sets of zero g brakes. i myself have purchased cat claws, zero gravity 04, zero gravity 06 brakes from him, and got zero g 05. We have all supported him in this way and encouraged him. Even though it is taking longer than anticipated, he is one man who is doing great things and is a great innovator. Let's just give him all the time he needs.



Mike, you are so right... With this post in mind I purchased a set of Zero Gravity '07 Ti brakes this week. They're great! :thumbup:

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airsoft510
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by airsoft510

are there any upgrades to the 07 0g brakes?

flying
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by flying

airsoft510 wrote:are there any upgrades to the 07 0g brakes?


I would be interested as well.
I went from 06 ZG's back to Mavics
I would love to save the 141 grams again. For me & where I ride
the ZG's just did not feather or slow me as well as a dual pivot.
But I would give them another try if something has changed.

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yourdaguy
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by yourdaguy

Flying-you might try adjusting the ZG's so that they are a little wider (more travel before they engage). The design of the power cam is such that it needs a little travel to kick in. When I first got my ZG's I didn't think they were very powerful until I used this trick and the pads seated. Now, I consider them very strong just like DA7800.
For certain parts stiffer is more important than lighter.

flying
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by flying

yourdaguy wrote:Flying-you might try adjusting the ZG's so that they are a little wider (more travel before they engage). The design of the power cam is such that it needs a little travel to kick in. When I first got my ZG's I didn't think they were very powerful until I used this trick and the pads seated. Now, I consider them very strong just like DA7800.


Thanks I no longer have them as I sold them.
But I did try that too. The thing is I have some very fast technical descents here & feathering is important too. So having them too wide open poses a bit of a problem in that regard. Also the wider open they were the less actual working travel seemed to be left. Meaning they get close to bottoming out on the bar & still not slowing rapidly enough for my style of riding. I am pretty methodical & having ridden the same places for so many years I have braking points in memory. Using those same points of ref I always overshot while on the ZG's
Finally I just gave in & went back to Mavics.
Thanks though perhaps I will try again sometime soon.

by Weenie


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