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OK, how does this work?
 

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Brian Nystrom
Joined: 26 Jan 2004
Posts: 5096
Location: Nashua, NH

7/6/17 5:05 AM

OK, how does this work?



http://store.corima.com/rear-corima-32-mm-mcc-splus-carbon-wheel-tubular.html

This looks like a Sheldon Brown "April Fools" creation. How does it not collapse?

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daddy-o
Joined: 12 Apr 2004
Posts: 3307
Location: Springfield

7/6/17 6:05 AM

Factory perfect?
Looking at the zoom-in on the website it looks like the spokes can't be adjusted or presumably, replaced.

Just to be contrary, wouldn't 'pushing' spokes be better?

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PLee
Joined: 08 Dec 2003
Posts: 3712
Location: Brooklyn, NY

7/6/17 7:48 AM

Obviously, the necessary strength and structural integrity is provided by the tubular tyre when it is glued on properly, preferably with Clement red adhesive, which is known for its rigidity . . . . . .

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Craig
Joined: 12 Jan 2004
Posts: 591

7/6/17 9:55 AM

"Factory perfect." Yup, I would guess that's it. I don't think it's a lot different that Mavic R-Sys, where the spokes weren't really in tension to begin with. Which is the misleading component of this wheel, our brains automatically think "spokes = tension" where I think when this wheel sits unloaded there is not tension or compression in the spokes. When in use there's just a whole lot of pushing and pulling going on, and a certain amount of rotational energy at the hub just standing still. Imagine not rolling, loaded, and only two pairs of spokes; top and bottom, as the hub is loaded the top pair of spokes goes under tension, the hub tries to rotate backwards but is held up by the bottom pair of spokes in compression.

Regardless of how or why it works, it's a stupid design, in my opinion.

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dddd
Joined: 11 Jan 2004
Posts: 3345
Location: NorCal

7/6/17 11:03 AM

After looking at this for a while, it seems to be based on a method of providing lateral rigidity with vertical compliance, and I am not joking.

The hubshell rotates back and forth very slightly in response to road shock, and as with R-sys wheels the spokes are more structurally stiff in compression than one might readily imagine.

The tubular carbon rim's stiffness would seem to be somewhat critical, but to varying extent that is also true of all other wheel's rims.

The spokes need an airfoil profile to better exploit this design imo.

Corima has been around so to speak, so I would not be totally dismissive of the validity of this design.

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Brian Nystrom
Joined: 26 Jan 2004
Posts: 5096
Location: Nashua, NH

7/6/17 11:21 AM

I'm trying to figure out the reason for the design

It seems that it would allow the hub to move somewhat relative to the rim, with the paired spokes maintaining a sufficient (?) degree of lateral stability. Is this supposed to be a micro-suspension system of sorts? I just can't see how this could be durable under high loads and/or on rough surfaces.

These are the wheels that are supposed to be standard equipment on the upcoming Look 785 Huez RS that's launching in October, the ad for which is where I first saw them. At first I thought it must be some kind of optical illusion and was stunned to learn that it's an actual product.

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Sparky
Joined: 08 Dec 2003
Posts: 19068
Location: PDX

7/6/17 12:11 PM

It gets wobbly when you put less than 300 watts into it. It is a new fangled training wheel...

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Jesus Saves
Joined: 16 Jun 2005
Posts: 1150
Location: South of Heaven

7/6/17 2:45 PM

It uses recycled material, including the business plan, from the Dollar Shave Club.

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Brian Nystrom
Joined: 26 Jan 2004
Posts: 5096
Location: Nashua, NH

7/7/17 5:54 AM

Apparently, they've been around for a while...

...and there are people actually riding them, though I haven't found any derailed reviews. The discussions I've seen have been about comparing them to other esoteric wheels like the Lightweight Mielenstein, which probably indicates the price range of these suckers. Who knows, maybe at that price range the laws of physics don't apply? ;-)

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PLee
Joined: 08 Dec 2003
Posts: 3712
Location: Brooklyn, NY

7/7/17 7:29 AM

We've seen other rims with long, unsupported arcs before that work fine. I have no doubt that, fresh out of the box, these wheels work nicely. My concern would be what happens if one of the spokes break. I wonder whether the wheel would be at all ridable. Interesting that they don't make a clincher version with the 32 mm profile.

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April
Joined: 13 Dec 2003
Posts: 6593
Location: Westchester/NYC

7/7/17 9:08 AM


quote:
My concern would be what happens if one of the spokes break. I wonder whether the wheel would be at all ridable.

I once came upon a rider on the side of road with one of those low spoke count wheels. (not even that drastic one, just a plain vanilla low spoke count wheel).

The wheel was too out of true to ride. And the spokes don't have a way to be trued on the road.

So I left him on the side of the road waiting for his wife to pick him up.

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Brian Nystrom
Joined: 26 Jan 2004
Posts: 5096
Location: Nashua, NH

7/8/17 6:37 AM

It doesn't take much

I broke a spoke on a 24 spoke rear wheel and it was enough to make the tire hit the chainstay. Fortunately, it was a conventional wheel and I was able to tweak the spokes enough to make it rideable. I've since add a Fiberfix emergency spoke to my on-road repair kit.

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