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Re: Gravitas Cranks

Posted: Mon Jan 14, 2013 4:37 am
by RudyMontana
I too preferred the original design. I do hope that those that end up with these are happy. After following the fiasco on the past two threads I was left shaking my head.

I would love a review after a few miles.

Cheers and enjoy!

Re: Gravitas Cranks

Posted: Mon Jan 14, 2013 8:42 am
by elviento
Iactually like the old alu crank. As long as it could be made with a proper hollow technology, it'd be a cool item to have on my bike, even if the weight is on par with the big names.

Gravitas Cranks

Posted: Mon Jan 14, 2013 4:45 pm
by Wingnut
The spider looks odd compared to the arm...don't mind it overall though...

Re: Gravitas Cranks

Posted: Tue Jan 15, 2013 2:20 am
by mythical
Let's see if it passes EN14781. :wink:

Re: Gravitas Cranks

Posted: Thu Jan 17, 2013 9:07 am
by cllrhodgen
:smartass: :lol:

Agreed!

Re: Gravitas Cranks

Posted: Thu Jan 17, 2013 12:37 pm
by stephen@fibre-lyte
Does it need to? I'm sure that it has passed all the tests that it needs to before being released to market, or at least I hope that it has. :wink:

Re: Gravitas Cranks

Posted: Thu Jan 17, 2013 2:36 pm
by HammerTime2
Tests? This is the United States. We don't need no stinking tests.

Re: Gravitas Cranks

Posted: Fri Jan 18, 2013 5:33 pm
by cllrhodgen
You've got to love Europe as a democracy - European Numbers are their way of reminding everyone that 'we are in charge here'!!! Even the mighty Bristish Standards have been sidelined for the Eurocodes! :roll:

Re: Gravitas Cranks

Posted: Fri Jan 18, 2013 8:27 pm
by jano
cllrhodgen wrote:You've got to love Europe as a democracy - European Numbers are their way of reminding everyone that 'we are in charge here'!!! Even the mighty Bristish Standards have been sidelined for the Eurocodes! :roll:


And what exactly is the problem? Or what is your problem? How does it relate to this thread?

Re: Gravitas Cranks

Posted: Sat Jan 19, 2013 3:11 pm
by djconnel
mythical wrote:Let's see if it passes EN14781. :wink:


Good blog post on EN14781 here. Jan Heine talks about his Rene Herse crank re-design passing the test.

It looks like something from Jacques Anquetil, excepting the # of teeth:

Image

The crank is competitively light, even by today's standards, with a Ti-spindle bottom bracket. Note only 3 chainring bolts.

On testing, though: if a crank can pass a test for a 90 kg rider, it's probably over-built for a 57 kg rider.

Re: Gravitas Cranks

Posted: Sat Jan 19, 2013 11:33 pm
by jano
djconnel wrote:On testing, though: if a crank can pass a test for a 90 kg rider, it's probably over-built for a 57 kg rider.


Not probably, certainly.

Re: Gravitas Cranks

Posted: Sun Jan 20, 2013 1:27 pm
by cllrhodgen
jano wrote:
cllrhodgen wrote:You've got to love Europe as a democracy - European Numbers are their way of reminding everyone that 'we are in charge here'!!! Even the mighty Bristish Standards have been sidelined for the Eurocodes! :roll:


And what exactly is the problem? Or what is your problem? How does it relate to this thread?


:unbelievable: :sorry: if you took offence at that - remember part of the EU is that it has a freedom of speech. If you don't like it, move on!

Personally... and i'm guessing you don't agree with me, not that it matters, it relates to the topic in question on the basis that if the cranks themselves do not pass the EN14781 tests they won't matter how striking and aesthetically appealing or the opposite of such they appear to many now will it?! :lol:

Re: Gravitas Cranks

Posted: Sun Jan 20, 2013 2:41 pm
by djconnel
According to the Jan Heine blog post I referenced, many high-end cranks don't pass the "racing" level of the test. There's different tiers.

As an aside, it looks as if it would be relatively easy to integrate a power meter with those crank arms, since the crank arms consist (apparently) of 3 simple hollow tubes. The main issue might be the hysteresis effects referenced by Stages for carbon deformation. But I strongly suspect that could be worked around.

How to build your own.

Re: Gravitas Cranks

Posted: Sun Jan 20, 2013 6:26 pm
by jano
cllrhodgen wrote:
jano wrote:
cllrhodgen wrote:You've got to love Europe as a democracy - European Numbers are their way of reminding everyone that 'we are in charge here'!!! Even the mighty Bristish Standards have been sidelined for the Eurocodes! :roll:


And what exactly is the problem? Or what is your problem? How does it relate to this thread?


:unbelievable: :sorry: if you took offence at that - remember part of the EU is that it has a freedom of speech. If you don't like it, move on!

Personally... and i'm guessing you don't agree with me, not that it matters, it relates to the topic in question on the basis that if the cranks themselves do not pass the EN14781 tests they won't matter how striking and aesthetically appealing or the opposite of such they appear to many now will it?! :lol:


Safety first, it's absolutely normal.
All products released to the market have to pas stringent tests to show they are safe for use, why would bikes be exempted?

PS: Freedom of speech is fine as long as the criticism is supported by some foundation other personal feelings.

Re: Gravitas Cranks

Posted: Sun Jan 20, 2013 8:33 pm
by Waldo
djconnel wrote:According to the Jan Heine blog post I referenced, many high-end cranks don't pass the "racing" level of the test. There's different tiers.


Without testing all "classic" and "boutique" cranksets personally such a statement is really just supposition, since there's no database of passing cranks. Many OEMs request certificates of conformity from us stating that our components conform to the appropriate norm; some of these require only an affirmative statement while others require data sets and other info. Others either request no info or perform their own testing.

While there are different norms for different use cases, it's not up to the manufacturer to select a norm that is not reflective of the intended use of their product. Each norm contains rather specific language dictating the type of bike to which it pertains.

I haven't dealt with anyone that intentionally uses a less stringent norm not reflective of the intended use of their product (manufacturers are more open and cooperative than one might expect at ASTM, EN, ISO, or UCI meetings). To be fair, the people you encounter at these meetings are generally actually manufacturing their parts and perform other tests beyond the minimum in the EN.

Others I'm sure are not so diligent. There are many wheels that do not actually pass various aspects of the EN norm, just as when we were in the crankset business I had a crank from a rather prominent competitor last 463 cycles on the EN test.

Some countries in the EU are much more stringent than others about adherence to the appropriate norm. In France, for example, they will buy a bike at a shop and then subject all components to the appropriate norm. There are large fines and stop sale orders that accompany a failing result (so I hear, fortunately we have no direct experience with this).

Lastly, we should regard a passing statement for the pertinent EN standard as an assurance of quality of safety. These standards are currently under review as they were initially written when aluminum components were much more prevalent than carbon; as such, many of the failure criteria or tests as a whole are not ideal for current product.