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PostPosted: Wed Nov 28, 2012 9:06 am 
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Joined: Tue Apr 22, 2008 4:31 am
Posts: 139
Here are some pics comparing the spider connection points on both chainrings. In both pics, the SRAM 50T ring is on top.

First off, the connection to the crankarm (hidden one)
Image

Now, all the other connection points on the SRAM one are different to the crankarm one, as seen here
Image


Here is the profile of the cutout on the crankarm (BB30 compact). You can see why the cahinring has some different machining.
Image

All makes sense now. For BB30 Compacts, the Praxis rings need to be filed slightly to match the profile as per the SRAM 50T chainring :smartass:

Problem solved. :thumbup:


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Posted: Wed Nov 28, 2012 9:06 am 


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PostPosted: Wed Nov 28, 2012 4:27 pm 
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Joined: Wed Nov 21, 2012 3:05 am
Posts: 199
thanks, that really helps, great pics.


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PostPosted: Mon Dec 10, 2012 2:35 pm 
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Joined: Fri Dec 15, 2006 7:45 pm
Posts: 3325
Location: Natovi Landing
I got my Exogram BB30 Compact 50-34, 172.5mm last week.

523g ... genuinely light even by WW crank standards.

...and less WW was the price ... $350 new from an ebay retailer


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PostPosted: Tue Dec 11, 2012 10:12 pm 
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Joined: Tue Sep 13, 2011 9:45 pm
Posts: 65
Image

So - pre-stripping.

170mm 53/39 BB30 and 549g, with a decent chunk of grease that came on the spindle, doesn't include the pedal washers or PF30 fittings.

Plan is to strip it back to bare carbon, 303 it, add some Praxis Classic rings and then stick it on my Firefly. When I have I'll use a camera rather than an iphone for a photo!

Praxis classic - SRAM red
112g - 139g
32g - 33g
Saving 28g

So pre strip 519g (there was 2 grams of thick blue grease on the spindle as well!)
For comparison my da7900 170mm 50/34 was 653g and I will be dropping a pf30 adaptor from the mix as well.

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Last edited by Stuartclark1977 on Tue Dec 18, 2012 11:40 pm, edited 1 time in total.

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PostPosted: Tue Dec 18, 2012 9:01 pm 
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Joined: Mon Jun 18, 2007 3:12 pm
Posts: 210
Location: NL
Has anyone tried to fit Red Black rings to the Exogram crankset? I don't like the new ring design. Does this fit and shift properly, also with older Red front derailleurs?


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PostPosted: Tue Dec 18, 2012 9:21 pm 
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Joined: Fri Nov 18, 2011 5:19 am
Posts: 836
You'd be doing a MAJOR disservice by using red black rings... the best part of the new crankset is shift performance and these rings perform light years better than the old.

That said, I'm sure they'll fit. Knock yourself out.


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PostPosted: Wed Dec 19, 2012 12:20 am 
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Joined: Tue Jun 08, 2010 4:58 am
Posts: 213
Location: Chicago
Stuartclark1977 wrote:

So - pre-stripping.

170mm 53/39 BB30 and 549g, with a decent chunk of grease that came on the spindle, doesn't include the pedal washers or PF30 fittings.

Plan is to strip it back to bare carbon, 303 it, add some Praxis Classic rings and then stick it on my Firefly. When I have I'll use a camera rather than an iphone for a photo!

Praxis classic - SRAM red
112g - 139g
32g - 33g
Saving 28g

So pre strip 519g (there was 2 grams of thick blue grease on the spindle as well!)
For comparison my da7900 170mm 50/34 was 653g and I will be dropping a pf30 adaptor from the mix as well.


I'm surprised by the weight difference on the Praxis rings. I'm also using the classics and mine were 98g and 31g respectively.


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PostPosted: Thu Dec 20, 2012 7:06 am 
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Joined: Mon Aug 16, 2010 9:47 pm
Posts: 114
Location: San Francisco, CA
Couldn't be more happy. Filing wasn't very hard nor do you have to file much at all.

Image

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PostPosted: Thu Dec 20, 2012 7:44 am 
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Joined: Tue Apr 22, 2008 4:31 am
Posts: 139
Wizzo wrote:
Couldn't be more happy. Filing wasn't very hard nor do you have to file much at all.


I presume yours was BB30 & compact ?


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PostPosted: Thu Dec 20, 2012 10:10 am 
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Joined: Mon Aug 16, 2010 9:47 pm
Posts: 114
Location: San Francisco, CA
Yes it is, BB30 172.5 with Praxis 52/36. I had the luxury to open couple of standard BB30 and GXP cranks with the corresponding BCD Praxis rings to confirm. Should've just read Page 8. :roll:

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PostPosted: Thu Dec 27, 2012 7:07 pm 
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Joined: Thu Sep 13, 2012 7:31 am
Posts: 17
Location: Slovenia
Wizzo wrote:
Yes it is, BB30 172.5 with Praxis 52/36. I had the luxury to open couple of standard BB30 and GXP cranks with the corresponding BCD Praxis rings to confirm. Should've just read Page 8. :roll:

Did you tried them yet?

How is the shifting with these 52/36?


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PostPosted: Thu Dec 27, 2012 11:10 pm 
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Joined: Mon Aug 29, 2011 8:55 pm
Posts: 169
Location: New Jersey
Great info here! Does anyone have a weight for a BB30 Quarq setup? Someone posted a gxp quarq combo which was heavy but I was wondering if the BB30 setup would be lighter.


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PostPosted: Fri Dec 28, 2012 4:26 am 
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Joined: Tue Dec 23, 2003 9:28 pm
Posts: 1769
Location: Unknown parameter
From reading this thread it appears that, including BB's, the 170mm BB30 compact I just ordered for my wife's bike will be within 1g of my old THM Clavicula BSA 175mm using the same rings. This is truly appalling. :shock: Maybe I miscalculated....


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PostPosted: Sat Dec 29, 2012 5:44 pm 
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Joined: Sat Dec 24, 2011 2:28 am
Posts: 40
Location: Roanoke, VA
Could someone do me a favor and weigh just the left-side arm/spindle of a BB30 style crank? A scale picture would be best. I ask because I am running a Quarq on an BB30 S900 and I am wondering how much weight I could save by using a Red crank on the left side. Also, does anyone know if this combo would work? Would the left/right arms be 180 degrees?


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PostPosted: Sat Dec 29, 2012 6:29 pm 
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Joined: Tue Sep 13, 2011 9:45 pm
Posts: 65
Image
Without lock-ring
Image
With lock-ring
Image
Spline pattern

This has lost the SRAM graphics but not been aggressively sanded.

I'm also not sure how the end shot of the spline weighs an extra 2 grams than the side on shot but should help you determine if the cranks would line up okay. (Maybe you should average them to a 179g without the lockring.)

They are 170mm 2012 SRAM Red BB30, hope that helps.

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Posted: Sat Dec 29, 2012 6:29 pm 


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