Strange Chainring Design - Manufacturing Fault?
buckmulligan
Posts: 1,031
Here's a festive conundrum for you. Thought I'd use the holidays to fit a few new parts to the bike, so I just broke out some Shimano 105 5750 chainrings that I ordered a few weeks back. They have a really weird design that I first thought was a manufacturing fault, but Googling some images, it seems as though it's deliberate as most of the images (other than a few computer renders) look the same.
Take a look at the weird asymmetric profiling around the edges of the holes at 10 o'clock and 12 o'clock in this picture. What's the deal with this, why would they seemingly deliberately manufacture it like that? Obviously it's purely cosmetic, I'm just curious as to what the purpose is.
Take a look at the weird asymmetric profiling around the edges of the holes at 10 o'clock and 12 o'clock in this picture. What's the deal with this, why would they seemingly deliberately manufacture it like that? Obviously it's purely cosmetic, I'm just curious as to what the purpose is.
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Comments
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easier to change gear it helps the chain slip off when the front detailer is swung across .... the cassette cogs have them as well0
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They have had these for years to help shifting.
You've missed the posts from people thinking theyve snapped the tops of their chainring teeth off on brand new kit.0 -
Sorry, my description wasn't very good. I'm not talking about the chainring teeth but these bits here, where it looks as though the milling machine has just given up halfway through! Just seems like an odd design and wondering why they're not a continuous curved profile like the other three.
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Is there something on the other face that it corresponds to?0
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I'd imagine it relates to the crank position (opposite side) and is either to stiffen that area or potentially to prevent some nasty sharp edge on a point that a finger could be trapped. Just guesses.ROAD < Scott Foil HMX Di2, Volagi Liscio Di2, Jamis Renegade Elite Di2, Cube Reaction Race > ROUGH0
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Actually, the silver image here has it offset from the crank
http://www.chainreactioncycles.com/shim ... lsrc=aw.dsROAD < Scott Foil HMX Di2, Volagi Liscio Di2, Jamis Renegade Elite Di2, Cube Reaction Race > ROUGH0 -
Could it have something to do with maintaining a constant cross sectional area on the outer diameter relative to the direction of the crank force? On the silver picture its filled in just below the crank.0
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Mystery solved!
After being satisfied that they were (apparently) meant to look like that, I ripped open the packaging and behind those weird two bits there are some round, hollowed out sections that presumably help picking up the chain when shifting to the big ring. 10 points to First Aspect.
Interesting that at least some of the Shimano stock images don't show it, that's what had me confused for a bit!0
