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Corima MCCs - Anyone have a clue how that rear wheel hangs together?

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Corima MCCs - Anyone have a clue how that rear wheel hangs together?

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Old 02-11-18, 05:50 PM
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Kimmo
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Corima MCCs - Anyone have a clue how that rear wheel hangs together?

Only just saw these yesterday; they look the bomb. The rear appears to defy physics, and an hour's googling left me with no clue...



Just... wow.
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Old 02-11-18, 07:25 PM
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darkhorse75
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All trailing spokes on the rear. Some black magic going on there.
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Old 02-11-18, 07:53 PM
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Yeah, they have to be working in compression as well as tension, but they don't look nearly beefy enough...
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Old 02-11-18, 07:54 PM
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Conventional spokes pivot at one or both ends and thus transmit tension only (in defiance of those who claim the hub "stands" on the spokes).

These (rear) spokes appear to be rigidly attached to the hub, and like beams, can transmit tension, compression, and shear forces. They are aligned to transmit the driving forces in tension, which would be at a maximum in racing. The rear wheel is probably not suitable for general use.
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Old 02-11-18, 08:08 PM
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Reviews have stated that this wheelset is durable; on par with Lightweights apparently.

I even saw one reviewer say they broke two spokes on the same side of the front in a crash, and the wheel didn't go out of true!!!

As for a tension wheel standing on its lower spokes, that's a pretty counter-intuitive concept to wrap your head around, but I believe Jobst. The lower spokes are the only ones to experience a change in tension as the wheel is loaded, therefore...

Excluding wheel-destroying incidents, any load applied to a normal wheel only reduces tension in some spokes. This oddball rear is probably an exception.

The counter-intuitive statements you come across in regard to tension wheels only seem wrong if you're failing to properly consider the how the tension unifies the structure.

Last edited by Kimmo; 02-11-18 at 08:13 PM.
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Old 02-11-18, 09:50 PM
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Just keep pedaling fast?
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Old 02-13-18, 02:58 AM
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Kimmo
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Originally Posted by bill kapaun View Post
just keep pedaling fast?
lol
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Old 02-13-18, 10:40 AM
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davidad
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https://www.bikeradar.com/news/artic...st-look-30422/
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Old 02-13-18, 10:55 AM
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Maybe something like these 21-spoke Campys? (from my local CL)

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Old 02-13-18, 12:31 PM
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Spokes in compression

I highly doubt the spokes are carrying any compression, regardless of how they are attached. They are still very slender and it doesn't take much buckling deflection to shed the load to the tension spokes. This wheel still relies on the tension spokes combined with the compressive arching resistance of the rim.
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Old 02-13-18, 01:00 PM
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Originally Posted by Ironfish653 View Post
Maybe something like these 21-spoke Campys? (from my local CL)

From my point of view I only like less spokes because they would be much easier to clean.
All the same that wheel sure looks nice.
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Old 02-13-18, 04:44 PM
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QUOTE=IrishBrewer;20167514]I highly doubt the spokes are carrying any compression, regardless of how they are attached. They are still very slender and it doesn't take much buckling deflection to shed the load to the tension spokes. This wheel still relies on the tension spokes combined with the compressive arching resistance of the rim.
You don't understand how a spooked wheel works. If you load the wheel at the axle the bottom spokes begin to lose tension and if the load is high enough the wheel will collapse. The top half of the wheel will still be intact.

Wheel stresses (Jobst Brandt)
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Old 02-14-18, 07:49 AM
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Originally Posted by davidad View Post
QUOTE=IrishBrewer;20167514]I highly doubt the spokes are carrying any compression, regardless of how they are attached. They are still very slender and it doesn't take much buckling deflection to shed the load to the tension spokes. This wheel still relies on the tension spokes combined with the compressive arching resistance of the rim.
You don't understand how a spooked wheel works. If you load the wheel at the axle the bottom spokes begin to lose tension and if the load is high enough the wheel will collapse. The top half of the wheel will still be intact.

Wheel stresses (Jobst Brandt)
Effectively, that's what I was saying. The lower spokes unload (perhaps not to the point of compression, however so I mis-spoke there - no pun intended) but my point was that the axle hangs from the upper spokes that have the highest tensile load.
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Old 02-14-18, 01:15 PM
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Why do people always try to reinvent the bicycle wheel? A standard 36 or 32 spoke, 2-3-4 cross wheel is a thing of beauty. It's supremely efficient and strong. To me, fewer fatter spokes like in the wheel above are ugly.
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Old 02-14-18, 01:45 PM
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Originally Posted by IrishBrewer View Post
Effectively, that's what I was saying. The lower spokes unload (perhaps not to the point of compression, however so I mis-spoke there - no pun intended) but my point was that the axle hangs from the upper spokes that have the highest tensile load.
The hub stands on the lower spokes and loads them in compression
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Old 02-14-18, 01:54 PM
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Originally Posted by davidad View Post
The hub stands on the lower spokes and loads them in compression
Think of the spokes as pieces of rope. You can't push on a rope is what one of my engineering profs liked to say. Jobst talks about the pretension shifting from the upper to the lower spokes so any "compressive force" in the lower spokes partially negates some of the pretension in those spokes but the net effect is that they are still in tension. In the case where a spoke was severely undertensioned, it could go into compression but it would start buckling at a very small compressive load (relative to its tensile capacity). Hence, you can't push on a rope.
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Old 02-15-18, 09:08 PM
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Jobst also shucked and jived in an attempt to cover his statements that reduced tension is compression (HAW!). He never produced any engineering analysis like a simple free body diagram of a conventional spoke. (That's a clue for the reader.)

So lets see...the hub stands on the spokes; the spokes stand on the nipples; the nipples stand on...uh, the uh rim tape; the rim tape stands on the tube; the tube stands on the tire. So Jobst doesn't even need the rim.
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Old 02-15-18, 11:20 PM
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*This* wheel, I suspect, and the Mavic Tracomp wheels do use compressed spokes...because they are designed to.

Your typical bicycle wire-spoked rim, however, is a tension system. If you'd like to assemble a wire-spoked wheel under no tension and sit on it, go ahead, but make sure you upload the video to YouTube for us.
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Old 02-16-18, 08:00 PM
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The marketing jargon describing how the Mavic Tracomp spokes work in compression is really sketchy.
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Old 02-16-18, 10:21 PM
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Originally Posted by IrishBrewer View Post
The marketing jargon describing how the Mavic Tracomp spokes work in compression is really sketchy.
While I'm not debating that, it's no less true. Without the compression ring installed, the spokes are easily turn-able, almost without a wrench. It's a case of doing something because you can, not because it solves some problem (though, to be fair, it does: using carbon fiber as a spoke material).
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Old 02-17-18, 10:37 AM
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Originally Posted by AnkleWork View Post
The rear wheel is probably not suitable for general use.
Not to mention they look inapt for disk brakes!

The pic wasn't posted on April 1st, was it?
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Old 02-17-18, 01:39 PM
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These must be tensioned like the Spinnergy wheels of old.

Spinergy (Jobst Brandt)
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Old 02-28-18, 02:16 AM
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Originally Posted by IrishBrewer View Post
I highly doubt the spokes are carrying any compression, regardless of how they are attached. They are still very slender and it doesn't take much buckling deflection to shed the load to the tension spokes. This wheel still relies on the tension spokes combined with the compressive arching resistance of the rim.
They either have to work in compression, and/or resist bending well enough for the wheel to hold appreciable tension (given the tapered section of the spokes, I'm tipping the latter plays a part).

Neither possibility looks plausible; that's what blows me away!

Furthermore - if they can pull that sort of funny business with the rear, then if it wasn't for UCI regulations, they could probably do a 10, 8, or maybe even 6 spoke front.

Last edited by Kimmo; 02-28-18 at 02:21 AM.
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