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thoughts on aluminium rings? (vintage cranksets)

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thoughts on aluminium rings? (vintage cranksets)

Old 05-08-14, 07:09 PM
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burnfingers
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thoughts on aluminium rings? (vintage cranksets)

Hey guys, got my hands on a cool 70s drillium crankset with aluminium alloy chain rings, curious if anyone has experience with something like this. Think it will it hold up under normal use?

My first thought was that it'd twist right out from under me the first time I stand on it, but it strikes me that this crankset has survived 30-40 years with no worse wear than some of my steel chain rings of far more recent make... Were they onto something with this? From what I can tell the rings and castings were made by SR and the spiders were finished + branded by OMAS, MAVIC, Raleigh, etc, in the 70s and early 80s.

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Old 05-08-14, 07:29 PM
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Looks like it is in good shape, and that only the rings are drilled, so it should be fine. And the rings look like they were drilled responsibly at the factory. Some aftermarket drilled arms and spiders scare me a bit when they look like too much material got removed.
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Old 05-08-14, 08:47 PM
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Looks like a Sugino Super Mighty which had factory drilled rings.
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Old 05-09-14, 05:17 AM
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No doubt it will hold up under normal use. The only shortfall is that the arm and spider were made as separate pieces and then pressed together and "swaged" (peened or spun over) to hold them together. This is more a theoretical than actual shortcoming; I've never seen one come apart. On the higher-end cranks, the arm and spider are cast or forged as one piece.
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Old 05-09-14, 05:26 AM
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Originally Posted by CroMo Mike View Post
...the arm and spider were made as separate pieces and then pressed together and "swaged" (peened or spun over) to hold them together. This is more a theoretical than actual shortcoming; I've never seen one come apart. ..
I have seen failed swaged cranks - but according to the PO, a simple aircraft clamp is all it takes to put things right.
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Old 05-09-14, 10:20 AM
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Stronglight made lots of cranksets with drilled aluminum rings back in the 70's and into the early 80's (the 104bis and 105bis models cone to mind) and I never heard of any of them having problems of collapsing under strain.... You shouldn't be concerned about using yours.....
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Old 05-09-14, 12:10 PM
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What is an aircraft clamp?
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Old 05-09-14, 12:36 PM
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A "P" clamp (google it). Unclear how this can be used to repair the crankset, though.
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Old 05-09-14, 02:07 PM
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Maybe a "C" clamp to press the arm back on the spider and re-sqaush things back at the back of the spider to shape??
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Old 05-09-14, 06:38 PM
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Originally Posted by CroMo Mike View Post
A "P" clamp (google it). Unclear how this can be used to repair the crankset, though.
oooh... bush, but effective!
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Old 05-09-14, 07:08 PM
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i built up a cheap fuji with steel rings for a girl i know. i found a $5 aluminum replacement for one, but left the smaller steel ring on there. it weighs a ton. i told her she should keep looking for an aluminum one.

steel rings should be put to another use, like wall art.
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