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 Post subject: Front wheel 0x, or 2 x
PostPosted: Sat Jun 30, 2012 9:03 am 
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Joined: Fri Sep 09, 2011 7:39 pm
Posts: 47
Location: Poland
what do you think about this .

2x
Image Image Image

0x
Image Image

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PostPosted: Sat Jun 30, 2012 9:38 am 
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Joined: Sat May 12, 2012 7:25 pm
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Location: Glermsford, Suffolk U.K
Well one is 2x and the other 0x. What do you want us to think?

The radial wheel could be heads in which is stiffer allowing thinner spokes.

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Posted: Sat Jun 30, 2012 9:38 am 


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PostPosted: Sat Jun 30, 2012 8:42 pm 
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I'm against radial spoking. Spokes pulling straight out from the hub can break the hub flange. The spoke is pulling against the thinnest part of the hub. With spoke crossings the spoke is pulling against a larger section of the hub. Less chance of breaking the hub flange.


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PostPosted: Sun Jul 01, 2012 7:17 am 
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Joined: Tue Nov 11, 2003 9:47 pm
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Location: Santa Cruz, California, USA
Most hubs these days have flanges that are strong enough for radial lacing. Best to check with the hub maker if you're not sure.

There's also 1x. Earlier this year I built a set of White Ind H1s with the front 1x because the hub shell has a reputation for deforming when laced radially.


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PostPosted: Sun Jul 01, 2012 9:51 am 
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A cross spoked wheel can be built with feel and comfort in it...

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PostPosted: Sun Jul 01, 2012 2:28 pm 
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When talking about stifness we must describe if are describing lateral stiffness or radial stiffness. When talking about comfort radial stiffness is important.

The ammount of radial deformation in a wheel when riding over bumps is minute. What is the stiffness of a 3x 32 spoke wheel 3000-3500 N/mm? This means a load of 3500N (that is ~5 times my body weight) would only cause a deflection of 1mm. I think the bike would jump up alot more with that kind of impact.

Also this paper demonstrates ( http://opus.bath.ac.uk/1418/1/Vogwell_P ... _4_563.pdf" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false; ) that the radial stiffness of a wheel is actually dependent of the stiffnes on the rim and not that of the spokes. this i becuase of the way the naths works. See eq 38 in the paper - spokes are alot stiffer than the rim so wheel stiffnes become rim stiffnes divided by approximatley 1 which equals rim stiffness. Counter intuative I know. So a radial wheel has just as much radial complaince as a 3x wheel if the same rim is used, which in reality is almost none.

Let use consider for a moment the vertical accelration produced when hitting a bump hard enough to cause a 1mm radial deflection in the wheel. I will assume a front end force from a bump of 3500N. If the weight distribution on the bike is 40F:60R then the weight on the front is ~ 395N for me + my bike. That means the resultant load on the front wheel is 3500N-400N =3100N.

Given I do not know the moment of inertia for my bike when it rotating about the back axle (which is the case when I go over a bump) I will simplify using F=ma for vertical acceleration just after hitting the bump. 3100 =40a therefore the accelration of the front wheel as it lifts of the ground is in the order of 77m/s^2. That is about 8g. Therefore with that kind of loading I hope you can see it is going to be uncomfortabe just to get 1mm of deflection radially in the wheel. However given the bike will ride up and over bumps you may not even see 1mm of radial deflection when front load reaches 3500N. So how will you notice the differnce in comfort between different wheels using the same rim and tyre but just changing the spoking pattern?

Tyres width, inflation pressure, fork compliance, handlebar and stem stiffnes + bar tape make a difference to comfort not wheel stifness.

If the hub maker certifies the hub for radial lacing then go for it, if not then its at your own risk.

In fact reading that paper has challanged alot of assumption I had about thicker spokes leading to a radially stiffer wheel.
So spoke count and thickness only makes a difference to lateral stiffness. Count count and thickness has little to do with radial stiffness - that is down to the rim.

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PostPosted: Mon Jul 02, 2012 11:01 pm 
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I get your question now. I like the wheels.

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 Post subject: Wheel flexural analysis
PostPosted: Tue Jul 03, 2012 6:29 pm 
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Joined: Fri Mar 26, 2010 4:24 pm
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bm0p700f wrote:
Also this paper demonstrates ( http://opus.bath.ac.uk/1418/1/Vogwell_P ... _4_563.pdf" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false; ) that the radial stiffness of a wheel is actually dependent of the stiffnes on the rim and not that of the spokes. this i becuase of the way the naths works. See eq 38 in the paper - spokes are alot stiffer than the rim so wheel stiffnes become rim stiffnes divided by approximatley 1 which equals rim stiffness. Counter intuative I know. So a radial wheel has just as much radial complaince as a 3x wheel if the same rim is used, which in reality is almost none.

In fact reading that paper has challanged alot of assumption I had about thicker spokes leading to a radially stiffer wheel.
So spoke count and thickness only makes a difference to lateral stiffness. Count count and thickness has little to do with radial stiffness - that is down to the rim.


I agree that the radial stiffness of any wire spoke wheel is so high that difference between wheels don't matter. However, I wouldn't base that opinion on this paper. I'm afraid to say that this is one of the worst papers I've seen published on this subject, and is full of flawed analyses, faulty assumptions, and one glaringly bad error that invalidates its conclusion. Although the paper lists several references, I don't think the authors read them (or maybe didn't understand them), since many of their analyses and assumptions are contradictory to the referenced publications.

In particular, the largest mistake made in the paper is assuming that the rim and spoke deflections are independent, and that the total wheel deflection is the sum of the rim and spoke deflections (in other words, they treat the rim and spoke stiffnesses as if they are in series). The reality is that the rim and spokes deflect in unison, not independently - when the wheel is loaded at the hub and the hub deflects downward, both the spokes and rim deflect together, which means that the rim and spoke stiffnesses act in parellel (not series). When flexural elements act in parallel, the total stiffness is dominated by the stiffest element. This means that wheel radial stiffness is dominated by the stiffness of the spokes, not the stiffness of the rim.

The relative importance of the rim vs. the spokes on radial stiffness can be seen in the data on a web page that this paper itself references, that of the Grignon wheel test (http://www.sheldonbrown.com/rinard/wheel/grignon.htm). In this test, the radial stiffnesses of a variety of wheels with different spokes and rim cross sections are measured directly. As can be seen from the data, the stiffest wheel in the test is actually the one with the 12mm tall Mavic GL330 rim, which is the lightest and shallowest (least stiff) rim in the test. This wheel has almost twice the radial stiffness of the Campagnolo Shamal, which has a rim that is more than twice the weight and 3 times the height (40 mm deep) as the GL330. The GL330 wheel is even 50% stiffer than the wheel with the deepest rim in the test, the 58mm carbon fiber Zipp 540. The reason GL330 wheel is the stiffest is because it has the most and thickest spokes of all the wheels in the test - 36 2.0mm straight gauge spokes (vs. 12 3.0x 1.2mm spokes in the Shamal and 18 3.3x1.2mm spokes in the Zipp 540). In other words, the stiffnesses of these wheels is dominated by the spokes, not the rim.

Looking through the paper, there are many other other flaws and poor assumptions in their overly simplified flexural analysis of wheel deflection that should be obvious to anyone who reads some of the other publications that are referenced. I would personally be ashamed to put my name to it, and I'm surprised it got published.


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 Post subject: Wheel flexural analysis
Posted: Tue Jul 03, 2012 6:29 pm 


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