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 Post subject: Alpha 340 wheel build
PostPosted: Thu May 26, 2011 12:50 am 
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I am going to be building a new set of wheels in the near future. I am very budget minded, so I don't want anyone chiming in with a "get some Edge tubs" post or anything. Good, sound, and budget focused advice definitely needed. Ok, here goes.

I am 165-175 lb (75-80kg) depending on what I've eaten on any particular day :P

I am considering Stan's Alpha 340's, Either the BikeHubStore SuperLight or Rotaz hubs in 24/28 spoke count, and Sapim Laser spokes, lacing 2x up front, 2x DS and radial NDS rear.

My goals:
1) Lightweight (duh) - I am currently riding on a Neuvation R28Aero4 wheelset. While very cool looking, they are a bit heavy at 18xxg for the set. I've also read on some durability issues with them, so part of my reasoning for the new build is to have another set to switch out/replace them in the event of any problems.

2) Durability - I ride some roads which I would not consider well maintained, and the R28s spoke count is 16/20. I assume the low spoke count requires more loading per spoke, and therefore places more stress at each of the mounting points on the rim than on a higher spoke count. The R28s may hold up, may not. Regardless, Neuvation is 15 miles away from me and they are under warranty, so I am not super worried about that, but if I build my own set, I figure a higher spoke count of 24/28 will be safer (with regards to durability/life), and I can get away with using a lighter Sapim Lasers.

3) Vertical Compliance - I would venture to guess that a higher count of lighter gauge spokes at a lower tension offer a little more elasticity than a lower count, higher tension setup. I am not really sure to be honest, and always appreciate good advice and informed opinions from experienced wheel builders.

4) Lateral Stiffness - I've been reading on WW about what makes a stiff wheel - Stiff rim, Flange diameter and offset from the hub center, and some bantering about spoke tension/ stiffness. I know the difference between tensile and ultimate strength, and I'd rather not approach the ultimate strength of any spoke, which means not allowing any individual spoke to reach the upper limit of its tensile strength. I reason that the higher spoke count would lower the overall tension on individual spokes, while more evenly distributing the tension on the rim and hub, making the overall stress on the wheel lower yet retaining a good amount of lateral stiffness. Am I way off here? I am not an extreme weight weenie, and am willing to trade a marginal amount of weight via a higher spoke count in exchange for a longer lasting wheel. Besides, the rim/tire/tube are the most important factors with respect to rotational mass, so the advantages of a couple extra spokes outweigh the weight penalty IMO.

So, that being said - Does the combo I listed look to satisfy my goals? With regards to my weight, will I have a problem using the Lasers and the Alpha 340s?


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 Post subject: Alpha 340 wheel build
Posted: Thu May 26, 2011 12:50 am 


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PostPosted: Thu May 26, 2011 2:58 am 
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Joined: Mon Aug 16, 2010 9:47 pm
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Location: San Francisco, CA
I have a set of Alpha 340s built on Alchemy Hubs with CX-ray 20/24 and they hover at 1203grams with stems. I don't know too much about Bike Hub Store but reading opinions about them vary but they tend to lean towards the favorable side in terms of what you get for your money. I've also seen some opinions on Circus Monkey as well to which they are in the same price range. If you want complete lateral stiffness I can vouch for Alchemy Hubs but however I am not sure if you are down with the price of the hubs. I have to say they are probably the best hubs I have ridden on. Others to consider are White Industries, C-4, Chris King, and Tune.

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PostPosted: Thu May 26, 2011 3:07 am 
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Location: Maryland
I looked into an Alpha 340 build, and ran into a couple of interesting factors.

1. The tech reps at Stan's suggest no tension higher than 95kgf. Check out http://messageboard.notubes.com for specifics.

2. When used with tubeless tires, the build tension can drop significantly when the tires are inflated. This makes building a strong wheel like walking a tight rope.

With your particular build, the arrangement you've chosen - 2x DS, radial NDS, will give you the greatest tension mismatch between sides. Thus, the tight rope gets quite a bit smaller as you must tension the spokes enough so that when inflated with a tubeless setup, your NDS doesn't go slack with load. Yet, you can't exceed 95 kgf building tension on the DS as that maxs out the rim in the scenario of standard tire/tube.

Long story short - in my opinion, go 2x both sides, if not 2x NDS and radial DS. Spoke count seems ok. Or try a Kinlin.


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PostPosted: Thu May 26, 2011 3:23 am 
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I have not really considered the tubeless setup. I don't have a problem lacing 2x all around. Would that be an adequate solution?

As for buying sweet Alchemy hubs, I would love to, and may later on down the line, but this is my first foray into wheel-building, and would like to start out on slightly less expensive components. :)


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PostPosted: Thu May 26, 2011 5:41 am 
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IF this is your first customset, I would go with BHS hubs and Kinlin rims. If you ever break em, you dont have to cry for 4 weeks...maybe 4 hours :lol:

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PostPosted: Thu May 26, 2011 6:14 am 
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Lol, I am not worried about breaking anything- i enjoy quite a few hobbies that require attention to detail. Maybe I'll just save up for the Alchemy hubs...


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PostPosted: Thu May 26, 2011 12:56 pm 
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mikebergy wrote:
Lol, I am not worried about breaking anything- i enjoy quite a few hobbies that require attention to detail. Maybe I'll just save up for the Alchemy hubs...



+1 to that.. Save a little extra and get x-ray spokes too
I have an extralite wheelset built around the alphas
They are super nice and to be honest Im a fat barstard, at my weight they could be a little stiffer but my wheelset is lighter than my friends campag hyperons Inc tires..

Save a little get the better hubs and build an amazing wheelset that's the whole point of going custom..
Youll be a happier cookie in the long run.

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PostPosted: Thu May 26, 2011 1:30 pm 
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That setup should give fair bang for the buck.

As for rear wheel most recommended lacing variants seems to be 2x on both sides or 3x/radial.

If you're concerned that your roads are really really bad and you'd give the wheels a hard time you may want to consider 28/32 spokes, but otherwise 24/28 seems to be generally acceptable for your weight (I weight the same).

Looking to do a similar build once ...

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PostPosted: Thu May 26, 2011 2:14 pm 
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Location: Alto, NM
JN2Wheels wrote:
With your particular build, the arrangement you've chosen - 2x DS, radial NDS, will give you the greatest tension mismatch between sides.


Not if they are laced heads-out radial on the NDS... which is typical.


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PostPosted: Thu May 26, 2011 2:20 pm 
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mikebergy wrote:
I have not really considered the tubeless setup. I don't have a problem lacing 2x all around. Would that be an adequate solution?


Not going tubeless makes things easier. And the best lacing pattern strongly depends on the dimensions of the hub you are using. The dimensions of the Rotax aren't listed... Best to find out what they are before deciding.


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PostPosted: Thu May 26, 2011 2:28 pm 
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mikebergy wrote:
3) Vertical Compliance - I would venture to guess that a higher count of lighter gauge spokes at a lower tension offer a little more elasticity than a lower count, higher tension setup. I am not really sure to be honest, and always appreciate good advice and informed opinions from experienced wheel builders.


The vertical compliance of wheels is essentially zero... and tension does not effect it. Fewer spokes and lighter spokes will increase it.

The tension and other details will effect the vibration response, but I've never seen an analysis or test of what the effect really is.


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PostPosted: Thu May 26, 2011 2:36 pm 
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rruff wrote:
Not if they are laced heads-out radial on the NDS... which is typical.


You've built many more wheels than I have, so I'll defer to your expertise... But, all else equal, a wheel laced 2x both sides should definitely have higher tension in the NDS than a radial NDS. Simply the physics say that the 2x NDS spokes are then pulling on the rim with the same lateral force as a radial setup, plus they have additional tangential forces that radials can't carry.

Anyway, my point was that with such a low maximum build tension (compounded by tubeless inflation losses), the OP should do everything possible to equalize spoke tensions from side to side.


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PostPosted: Thu May 26, 2011 4:35 pm 
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The effect of the deviation of a crossed spoke from a straight path from hub to rim is quite small actually... and certainly the crossed spokes are a couple mm farther outboard. It's essentially a wash.

Equalizing tension on both sides isn't the best goal, since lateral stiffness goes up exponentially with bracing angle. The first and best thing is to make the DS offset as great as possible (ie derailleur almost hitting the spokes), and then usually ~2x that angle on the NDS works the best.

I wouldn't worry too much about using tubeless tires if you are building the wheel yourself anyway... simply do the final tensioning and truing of the wheel with the tire installed.


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PostPosted: Thu May 26, 2011 5:22 pm 
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Location: MS, USA
95kgf? I thought the limit was 110kgf?

Anyway, the rims can handle it IME, my DSR is around 120kgf.

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PostPosted: Thu May 26, 2011 7:12 pm 
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woz9683 wrote:
95kgf? I thought the limit was 110kgf?


I took a look at the Stan's message board referenced above and searched for posts on Alpha 340 spoke tension, and found that the people who work for Stan's can't even agree.

In one post, Peter Pelychaty (Product & Warranty Manager) says, "We recommend a maximum tension of 92 kgf," and in another post he says, "The max tension without a tire should be 95kgf".

In one post Bob Nunnink (inside sales associate) says, "CX-Rays will work. Recommended spoke tension on the drive side is between 95-100 kn," and in another he says, "We recommend a spoke tension of 95-100 for our rims The cx-ray build better at higher tensions and are not a good choice to use with our rims." (So, he is consistant with his tension recommendations, but inconsistent on his spoke recommendation)

In yet another post, Rich O'Neill says, "we ahve been building our wheels as of right now on the higher side of tension from 100-110."



I'm not sure any rim manufacture has done a careful study of allowable/recommended spoke tensions. I think they simply have simply gravitate toward a single number which seems to not cause too much trouble most of the time, without taking into account that heavier and stronger rims can tolerate higher tensions, or that the number of spokes can affects maximum tensions.

In my past life I was custom wheel builder, and after working with a variety of different rims, I've found that maximum tensions are dependent on rim weight (which is proportional to cross-sectional area) and the number of spokes. A rough approximation can be found from this formula:

Max. Tension = Kt * W / N

Where:
Kt = Tension Constant (value is typically between 8 and 9, with units of Spokes/Kg)
W = Weight of rim
N = number of spokes

This formula works well for spoke counts of 24 and higher. For lower spoke counts, other factors come into play.

So, if the Alpha 340 rim weighs 360 grams, then for a 32 spoke wheel the formula estimates that the maximum tension would be between 90 and 101 kgf. Which, for this particular case, seems to line up with the Stan's recommendation.


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Posted: Thu May 26, 2011 7:12 pm 


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