Weight Weenie Specialized S-Works Spider

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Qman
Posts: 118
Joined: Wed Oct 23, 2013 9:55 pm

by Qman

I thought people might be interested to see how I designed and built a weight weenie spider for a Specialized S-Works crank. So, I’ve shown some photos and brief descriptions below.

I purchased a used S-Works crankset from this forum. It had the graphics removed and both the carbon arms and the aluminum spider had been painted black. I decided that I preferred to see the carbon weave so I stripped the black paint off the arms and refinished them with a gloss clear coat. I loved the new look, but now the spider looked a little rough so I decided to strip the paint off of it too. Underneath the paint, the spider was a bit scratched. But more importantly, I found the stock spider too heavy (60g) and rather ugly. I’m not a fan of the specialized twisted shapes, and I don’t like the combination of carbon arms and silver spider. So, I decided to design and build a new spider to reduce the weight and improve the looks.

First, I measured the original spider. Then I created a 3D solid model of the spider to establish a baseline for the new design:
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Then, I created a new design based on the original geometry, but changing the style to better match my Extralite chainrings:
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And I created a second design for comparison:
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I refined the two new designs and found that both of their masses were approximately 40g. Next, I compared stress and deflection between the three designs. I used a torsion load due to the chain tension, and a side load due to shifting gears. The design with the open holes had significantly higher stress and deflection. That design would be much easier to machine, and I like the looks of it, but I decided to go with the stiffer design.

Next, I programmed the CNC mill to create the design:
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And machined the part:
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The part after machining:
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I polished everything except inside the pockets:
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Then black anodized:
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Final mass is 38g, compared to 60g for the original (sorry about the fuzzy photo):
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Here it is mounted on the crank and the bike:
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Total mass with bearings, shields, wavy washer, and chainrings is 535g.
I'm very happy with it. I think it looks much better and it's dropped a little weight. I've only just got it on the bike, but so far everything works perfectly.

dereksmalls
Posts: 2305
Joined: Tue Aug 02, 2011 9:20 pm
Location: New Zealand

by dereksmalls

That is awesome! Brilliant work and only 1 gram heavier than the compact spider that Lightning make for their cranksets of the same design

by Weenie


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Flyfishing3
Posts: 46
Joined: Wed Oct 23, 2013 6:58 pm
Location: Western Pa

by Flyfishing3

Props

520 Dan
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by 520 Dan

Did you do the 3D modeling in solid works?

shimmeD
Posts: 544
Joined: Thu Jun 28, 2012 10:52 pm
Location: eNZed

by shimmeD

BEAUTIFUL!
Less is more.

swiftvelo
Posts: 52
Joined: Tue Jun 05, 2012 1:57 am

by swiftvelo

Any chance you could make and aero model ? Something that works with praxis rings?

SLCBrandon
Posts: 709
Joined: Fri Oct 05, 2012 3:52 am

by SLCBrandon

You should sell these.....

Qman
Posts: 118
Joined: Wed Oct 23, 2013 9:55 pm

by Qman

The modeling was done in Creo and the FEA was done in SolidWorks.

An aero model would probably be easier to machine overall, but the shape would be a little tricky under the arm - I think it would need a little extra clearance there.

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Rick
Posts: 2034
Joined: Sat Aug 29, 2009 4:30 pm

by Rick

Awesome job!

jmpsmash
Posts: 11
Joined: Wed Nov 21, 2012 11:01 am

by jmpsmash

Incredible work.

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j0oftheworld
Posts: 47
Joined: Thu Aug 21, 2014 6:24 pm
Location: Phoenix, AZ

by j0oftheworld

Those are beautiful!
JasonM. Tempe, AZ
'14 SW Roubaix / '16 Allez Sprint

njee20
Posts: 545
Joined: Thu Jan 12, 2006 5:58 pm
Location: Surrey, UK

by njee20

Good effort, that looks great!

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F45
Posts: 1077
Joined: Wed Jun 08, 2011 6:08 am

by F45

Every man's dream is to be able to do just this sort of thing in his garage. Very nice.

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ITTY
Posts: 221
Joined: Wed Apr 09, 2014 8:08 pm
Location: Bremerton, WA

by ITTY

Lovely work. As F45 said, this is exactly the sort of thing I wish I had more time and money for. Do you own the CNC mill, or do you have access to one at work/school?
Moloko Plus 6.24 kg

"We haven't located us yet"

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PSM
Posts: 1706
Joined: Tue Aug 28, 2012 2:45 pm
Location: Stockholm, The Arctic...

by PSM

Pro!

by Weenie


Visit starbike.com Online Retailer for HighEnd cycling components
Great Prices ✓    Broad Selection ✓    Worldwide Delivery ✓

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