Rear Wheel Hub Design Question
 

Wouldn't it make sense to have a slightly larger flange on the non-drive side of a rear hub, in order to make the spokes the same length for both sides? Then you could just use spokes of the same length rather than needing two different sets of spokes. Am I missing something, or is it just that it's not a real concern because spoke breakage isn't a very common failure?

I'm looking at the VO touring hub that can be broken down without tools, so you can replace spokes, etc. If companies don't worry about spoke breakage because it isn't a real issue, wouldn't that mean a hub like this isn't really necessary to begin with? Would I be wasting my money for something that isn't really a problem?

Yep! Phil Wood does exactly that on their rear touring hubs. 57.8 mm on non drive side flange, 54.5 on drive side flange. Here are the results for my wheel on a spoke length calculator...

EDIT: Apparently the flange size difference is only on the older Phil Wood hubs. See posts 17 & 18 below.

It would make sense from the home mechanic’s perspective.
But its not as beneficial for the wheel building factory. They’re already set up to cope with plenty of different spoke length. Having two sent to the build station is no big deal.
Spoke breakage DOES happen. But not that often. And even if both sides take the same length spokes, you still need to have that length available.

I don't have personal experience with that hub, but the video I just saw looks like you have to remove the cassette before you can service the hub "without tools." So you'll still need a cassette removal tool to change spokes.

I presume you are referring to the VO hub mentioned by the OP. FWIW, my PW rear hub does not need a tool to take the rear cassette off the hub. Nice and handy, but then I have not had any spokes break on that 48 spoke hub while riding - only once in an "accident" when the RD went into the wheel after the black idler wheel came off (screw unscrewed.

Dish still is required to get the cluster of all those cogs in, and so an IGH, Dishless, still makes a stronger wheel .

that being said I got a lot of tours done with an old Phil 48 spoke rear freewheel hub, had a couple spare spokes in all 3 lengths ,
in my panniers , only ever needed one, , drive side, naturally ..

only needed to bring freewheel remover, borrowed the Big wrench from a local, then we went to the Pub for pints.


...

I agree with dabac, a wheel manufacturer that builds up lots of wheels has no incentive to pressure the hub manufacturers to do that. A wheel builder that only makes a small number of wheels is unlikely to get the attention of a company like Shimano.

I used to buy spokes from a local bike shop, they had a good price on the spokes to build one wheel plus they threw in a few spares. But they moved out of town, other local bike shops want a fortune for enough spokes for a wheel. So now I buy in bulk on line when I build up a wheel. I use Wheelsmith spokes, that means buying a bag of 50 for each length.

I used Sapim nipples for my last two pairs of wheels. On the most recent rear wheel that I built, I used these nipple washers on the drive side. They add about 0.7mm to the length of the spoke that you need.
Round PolyAx (HM) Washers (20 pieces)

By using those nipple washers on the drive side, I could use the same spoke length on both sides. I am not saying that they will always save you from needing two lengths, but in my case they did.

It would be nice if only one length spoke was required for a bike but it's not that big a deal to carry spares in 2 or 3 lengths. More important would be to design rear hub spacing/diameter to minimize dish, to increase wheel longevity for loaded touring use. AFAIK the only cassette hub that offers zero dish is the 145mm DT Swiss 540, used by CoMotion for touring singles, which is a $310 hub on sale. Phil Wood used to make the FSA hub with very little dish (in the 7s freewheel version), a custom version sold by Rivendell, which has been discontinued.

The only advantage of the VO GC hub over a Shimano XT is it's replaceable sealed bearings with no possibility of bearing cup wear, so potentially a longevity advantage - but also consider that the VO hub costs as much as 3-4 XT hubs.

AFAIK the only truly dishless IGH is Rohloff Speedhub (29mm flange spacing/100mm PCD both L&R). IGHs generally do reduce dish over cassette hubs but the only one that has symmetric flange spacing and diameter is Speedhub.

You can build with asymmetrically-drilled rims to reduce dish, Velocity sells a couple models (A23 and Synergy, discontinued).

To start with the effect of flange size varies either the number of spokes and crosses. It's greatest with a radial pattern where all the spokes go to the edge of the flange. It's least, approaching zero, on a full tangent build, ie. 36h x4 where all the spokes come down to the line of the axle. Everything else is in between, but what matters is that actual line the spokes take.

That said, the main goal isn't about spoke length, but bracing angle which determines the tension right and left. In that vein, you'd want to make the right flange bigger, to increase that bracing on that side. Making the left would be counterproductive, make things worse, or at best, having little effect.

No, you can remove the freehub with cassette attached without tools. The point of the hub is largely that you can replace spokes in a pinch without having to use a cassette tool.

Still, if someone wanted to make a hubset that use all identical spoke lengths, it’d be easy enough to compensate the geometry for the larger diameter NDS flange.
Moving the flange a few mm inwards would retain the spoke path and lateral bracing angle with few to none consequences.

Sorry, but not true with tangent spoke patterns. The spokes lead down close to the line of the axle, so the spoke length is unaffected by flange size.

It same length spokes are desired for some reason, it might be possible by reducing the number of crosses on the right, or on both flanges, then tweaking the flange size.

In any case, the goal of a lower tension different right and left should trump all others. That's done by increasing the right side bracing angle, a goal achieved with a larger right flange combined with reduced cross, ie. The larger flange also mitigates the torsional effects of reduced cross since the spokes pine of action is moved out.

[QUOTE=seeker333;19945465. You can build with asymmetrically-drilled rims to reduce dish [/QUOTE]

Though, if rim is narrow all you have is at most is half its width in shifting the holes,
drilling an asymmetric rim extrusion...


(Like drilling a 45mm wide rim, Fairbanks AK, Snow Cats, off center, or the even wider 4" fat bike rims )




:innocent:

One thing I find a bit frustrating is front hubs, not rear. I built up a new dynohub wheel last spring, planned to use it on a bike with rim brakes but I thought that some day I might want to be able to use that wheel with a disc so I considered using a disc type hub. I understand why SP used a larger diameter flange on the disc side, but why could they not use the same flange diameter also on the other side? It is an undished wheel, but I still would have had to buy two bags of spokes for that wheel because they used different flange diameters.
http://www.sp-dynamo.com/8-series-pic/PD-8-QR-01.pdf

Since it was for a rim brake wheel, I bought the non-disc version of the hub to avoid the extra cost for spokes.

I'm not sure where you are getting your dimensions. For the ones listed on their website, they are both 59mm. All the ones I've worked with...3 sets...have the same dimensions on both flanges.

Cycco, I'm using the hub dimensions chart at the PW website. Spoke hole diameters (called hub flange diameter at calculator above) of 57.8 and 54.5 on an 8 speed freewheel hub. All things being equal there should be a 3.3 mm difference in flange diameter.

You are working off some very old information. All of their cassette hubs have the same flange diameter and have for more than 10 years. My 2005 FSC hubs have the same flange diameter.

I don't know what to say Stuart. My hub is at least 25 years old but if you click on "Phil Wood hub dimensions" at the home page of the current website it will show the same dimensions that I posted for an 8 speed freewheel touring hub. The same numbers are listed for the cassette versions.

Phil Wood & Co.
http://www.philwood.com/philpdfs/whe...ding_break.pdf

Spoke length came out perfect entering those figure into the calculator. I don't have a caliper to measure the flanges on the built up wheel but eyeballing with a tape measure the left flange appears to be a few millimeters larger.

edit: I see the problem now. Phil Wood is posting old numbers at the pdf file. When you click on the various hubs on the home page your numbers come up. They should delete the pdf link from their homepage! That said, my old hub has the two flange sizes. You are correct, they have been changed!

A lot of cassette bodies just pop off now with a firm pull.

If you get a few extra bodies, it makes swapping cassettes really easy.

My PowerTaps are like that and they are based on DT hubs which also just pull off.

I noticed that too and haven't had time to post. I'm not sure they should delete the PDF but they should update it. There are still some old freewheel Phils floating around out there.

As for the flange sizes, that's what bothered me about the PDF originally. All of the Phils I have are the same size on both flanges.

Spoke breakage is very unlikely when the wheel is built for the intended use but just because a component has different features and costs more doesn't mean it's a waste of money. I have that hub. It goes around with a nice buzz.

IDK SP, but Schmidt ,

has a little dish on the front disc 6 bolt *, to make clearance for the disc, but did not use 2 different lengths, per side.

*they call these the 'classic' now .. a black, 32 hole, the left flange is closer to the hub shell center band..






.....

I use Shimano Deore hubs for my bikes and find, with 559 (26") rims, the lengths on both sides are nearly the same for both front and rear hubs. Lengths vary from about 263mm to 266mm, so I just use, and carry, 265mm spokes.