question upon "half-radial" on rear wheel

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bobbyOCR
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by bobbyOCR

I did a 27h wheel like this. Dura Ace hub to velocity Aerohead. Brilliant wheel. Do it.

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agilismerlin
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by agilismerlin

so why did mavic go radial drive side with the elite's

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amerliN

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bobbyOCR
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by bobbyOCR

isopulse. I don't think it's quite 'radial', more tangential to the axle. At least, I think it is.
Last edited by bobbyOCR on Fri Jan 18, 2008 1:25 am, edited 1 time in total.
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agilismerlin
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by agilismerlin

i have been trying to find some info on the isopulse rear hub - still trying

i just bought this rear wheel


funny, all the wheelsets sold online say radial non drive....found this funny and innacurate :lol:
amerliN

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tommasini
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by tommasini

WHen Mavic put radial on the drive side it allowed those FAT spokes to be as close to the cassette as possilbe. If the crossing spokes had been drive side the dish for those straight pull spokes (with their very large mating surface on the hub) would have been horrible.

GrahamB
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by GrahamB

tommasini wrote:WHen Mavic put radial on the drive side it allowed those FAT spokes to be as close to the cassette as possilbe.


That's partly true, but has nothing to do with fatness. The elite spokes are .9mm thick, just like CX-rays. They're much wider in the other direction, but that's irrelevant for crossing.
Graham

GrahamB
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by GrahamB

bobbyOCR wrote:isopulse. I don't think it's quite 'radial', more tangential to the axle. At least, I think it is.


It's exactly radial on the drive side. The NDS has both inside & outside spokes attached at the centres of lugs, rather than inside & outside a flange. That might be what the "isopulse" is about, but I suspect it's purely manufacturing convenience converted to a marketing slogan. They're not particularly more or less tangential than a regular crossed pattern.

The other advantage of crossing on the NDS (other than the minute change of dish-angle) is that crossed spokes effectively have a lower Young's modulus: when you tension them, they both straighten and extend linearly. That means with less tensile load, they can be pulled further. Conversely, they can be released further without losing tension, since the crossing causes them to bend and take up the slack that would occur if they were radial. That's exactly what you need to stop the low-tensioned NDS spokes going slack... although you lose stiffness as a result.
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bobbyOCR
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by bobbyOCR

radial drive = really stupid

congratulations again mavic for proving you're pretty bad at building good wheels.
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Miller
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by Miller

bobbyOCR wrote:radial drive = really stupid


Mavic's explanation goes something like this, I believe. In a normally-laced wheel, almost all the drive torque comes from the driveside, since the hub shell twists slightly under load and doesn't deliver much torque to the NDS. Mavic think this is 'bad' for some reason I can't recall. By making driveside radial, driveside spokes can flex further, thus allowing the hubshell to transmit more torque to the offside. This is 'good' for some reason I can't recall.

All it goes to show is that there are many ways to lace a wheel.

rruff
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by rruff

bobbyOCR wrote:I did a 27h wheel like this. Dura Ace hub to velocity Aerohead. Brilliant wheel. Do it.


Doh! That is a good pattern in general, but you really need to put the NDS spokes heads-in. The lateral stiffness suffers a lot with heads-out on a triplet.

BTW, I laced a 28h DA hub triplet style with 21 spokes on a Nio30 rim. Seems to work great.

GrahamB
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by GrahamB

Miller wrote:
bobbyOCR wrote:radial drive = really stupid


Mavic's explanation goes something like this, I believe. In a normally-laced wheel, almost all the drive torque comes from the driveside, since the hub shell twists slightly under load


I doubt they say that, because it's utter bollocks. Modern large diameter alloy hubs don't twist.

OCR, care to elaborate on your "radial drive side = stupid" comment? Shimano used it too, until the very latest version, but maybe their engineers also know less about wheel building?
Graham

Phill P
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by Phill P

I'd like to build a 27 spoke triplette like Boby, but dont' like the idea of every 4 hole being left exposed. What I might do instead is a 24 spoke wheel using a 24 spoke rim. As long as the spokes holes are drilled centrally this would work and look cleaner, and have as many drive side spokes as a 32 spoke normal wheel.

I figure with some thing like a Deep V rim it would make a pretty tough wheel. I ride the older zonda wheels without the machining. 30mm rim etc. Been pretty good, but I have broken one DS spoke in less than 10,000km so few more spokes would be good. Wasn't too impressed with how long it took to get the replacement spoke (old stock of course now) and the fact the spoke cost $15, leads me to want a custom built with a few more spokes for the next wheel.

Would like niobiums, but think they might be a little too thin walled for me, and they do cost a fair bit more than deep Vs (I think).

Front wheel might be 20 spoke with fusion rims (keep it in the family).

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Miller
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by Miller

GrahamB wrote:I doubt they say that, because it's utter bollocks. Modern large diameter alloy hubs don't twist.


This is how Mavic describes "Isopulse":
Specific hub and lacing with spokes that are radially mounted on the freewheel side and are crossed by two on the opposite side.
_Increased stiffness due to a better tension balance between each side of the wheel
_Greater efficiency due to better transmission of power

fdegrove
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by fdegrove

Miller wrote:
GrahamB wrote:I doubt they say that, because it's utter bollocks. Modern large diameter alloy hubs don't twist.


This is how Mavic describes "Isopulse":
Specific hub and lacing with spokes that are radially mounted on the freewheel side and are crossed by two on the opposite side.
_Increased stiffness due to a better tension balance between each side of the wheel
_Greater efficiency due to better transmission of power


Hi,

The ISOPULSE idea stems from Mavic's MTB wheels. They ported the idea to some of the road wheels but seem to have given it up for some reason.

While the ISOPULSE system would bring a more equal spoke tension for DS and NDS, so does Campa's G3 spoking pattern, Fulcrum's 2:1 or the triplette lacing pattern if you like.

I very much doubt the ISOPULSE system actuallly improves transmission of power though. Intuitively I'd say it feels quite the opposite to me.

IIRC Spinergy and Speedcomposites still use this system to build their wheels.

Ciao, :wink:
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rruff
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by rruff

Phill P wrote:Would like niobiums, but think they might be a little too thin walled for me, and they do cost a fair bit more than deep Vs (I think).


Niobium rims aren't expensive if you live in the USA. They are center drilled but Velocity rims aren't.

As for those pesky extra rim holes, I just put a little black electrical tape over the holes and it is invisible until you get close.

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