Mr IGH

Quick! Call the engineers and Campy and tell them their Zonda wheels don't meet your engineering principals. Then alert DT that their multiple lines of rims that come with drillings from 20H to 32H are not designed properly and will fail. Next, use your engineering degree to show how it's worse for a rim to have an extra hole un-tensioned compared to tensioned hole.

The silliest statement you've made is that rims have very little strength of their own. You can't have build very many wheels to make such a wrong-headed claim.

LOL, earth science isn't really the background you need to make statements as you have .....

In the meantime I'll do the cycling equivalent of running with scissors by continuing to use my most dangerous wheel.

Kontact 

I can break a rim with my hands, something I can't do with a wheel. Rims become strong because they are under compression from the spoke tension.

The Zonda doesn't have extra spoke holes with no spokes in them. LOL. We aren't talking about whether 20 hole rims are a good idea or not, but whether rims designed for 32 spokes are built to withstand a much larger gap you'd have when you skip a spoke rather than drill the rim for an even number of spokes. LOL.

A 24 hole rim puts the spoke holes 81mm apart. A 32 hole rim puts the holes 61mm apart, so when you skip a hole that's a 120mm gap - much larger than the 24 hole rim.


So I don't know what point you're making, other than that you didn't understand the comparison I was making. LOL.

pesty

As others have said... I wouldn't skip holes on the rims. If you really want to do 24, buy new rims and re-use the hubs. That's essentially what I did with some old Ultegra hubs. 32h hubs, found a good deal on some Kinlin rims, but they were only 24h. Laced the rear with 8 spokes NDS (1x), and 16 spokes DS (3x). the front I laced radially skipping every 4th hole on the hub. I'm just over 200lbs, they work perfectly and are currently my most used, and second favorite wheel set. My favorites are factory built HEDs that I save for weekends and special rides. One thing to note if you do decide to do any radial lacing is that some Shimano hubs don't have a thick enough flange to support the load and may crack. It takes some digging, but you can find that information on si.shimano.com in some of the old docs.

Mr IGH

Let me help you understand. First, remember that the same extrusion is used for a 20 hole rim as a 32 hole rim. Same thickness, same weight except for the difference in hole count (this is a fact) . Now think about a spoke hole with a nipple/spoke under tension with stress on the hole. Next think about a spoke hole without any nipple/spoke so that there's no stress on the hole. OK, now here comes the real hard part: Which one is under more stress; the hole with a tensioned nipple/spoke or the empty hole? Read up and understand the principal of "engineering superposition" before you try to answer or your just going to give the same mis-informed reply and continue to be just flat out wrong.

I'm still running with scissors!!!!!

Kontact 

"It's a fact" that SOME rims like the DT460 come in drillings from 20 through 32. It is also a fact that a DT 460 does not come in 16 hole drilling, and it is a fact that if you skipped holes in a 32 hole rim the span between spokes at a skip is the same as the span between a 16 hole rim. If the DT 460 was strong enough for spans large enough for 16 hole lacings, it would come in 16 hole versions.

That isn't engineering, but basic arithmetic. You're treating a minimum of 20 hole rim as a 16 hole rim. Do you understand that?

20 hole rims have the holes 98mm apart, 32 have the holes 61mm apart, and you have gaps that are 122mm apart, which is an extra 24mm more than DT ever drills this rim (122-98).


As for the stresses, rims need to be able to resist spoke tension, road compression and lateral forces. What you did might work in certain directions, but you have induced an outward force in the rim on those sections because there is no tension on the missing spoke spots, and you have made that area susceptible to lateral loads.

I don't know if you are being so caustic because you are defensive about the wheel you spent time building, or if you never thought about the unsupported spans you get skipping spoke holes and forgot that skipped hole makes the span double that of a base drilling. Or maybe you just are an angry person. But if I had a an I-beam that was strong enough to span a gap 98m wide, I wouldn't use it to span 122 meters. That's what you did with your wheel build.

pressed001

Anyway, I have decided to lace them as 32 which will match the hubs and rims. Found that Sapim Lasers were the best bang for the buck and ordered them after calculating lengths and double checking.
I am looking forward to the build and to trying the SL42's. The CXP 30's that I have now we're so great and will be missed. I beat them up and they stay straight as arrows.

pressed001

After all of your comments it was decided to run all 32 spokes. As this was my second from-scratch wheel build, I was happy that the spoke lengths worked out perfectly. Spokes are Sapim lasers and the nipples are Sapim polyax brass. The rims are H+Son SL42's with a 557 ERD. Spoke lengths are 261mm radial front and 270/272mm 3-cross both sides for the rear. The hubs are Dura Ace 7700.

To keep this build as budget as possible, the rear hub was re-used from the old wheelset. Since the front hub was Ultegra and had pitting in one cone, a new-used DA 7700 front hub was purchased for 40 Euros. Before building the wheels, both hubs received new shimano grease and bearings. The DA grease was applied sparingly. The cones look perfect and there is a very slight wearing on the cups but no pitting.

















So far the wheels have seen about 50km. I have to say that they are very smooth rolling thanks to the great hubs. These wheels are heavy, I know it. But I haven't attacked any hills or mountains yet, so I haven't yet felt their weight after a 1000m climb. So far they are great in the flat, really great. They accelerate decently and when up to speed, they keep it. All summed up, I dig them. The only thing I would change is the finish as the polished is a bit too bling for me. A brushed finish would be optimal.

Notes: H+Son says that the SL42 rim is produced in many different drillings. And they do, however the polished only come in 32 or 36 hole. All of the black finishes for the SL42 come with the brake surface coated as well. This means that the surface will wear and not look nice after some time.

JohnnyBeton

Hi.
I am the author of this diagram and the calculations that are fitting with.
I published this diagram on the Bicycle Wheel Building FB Group in june 2018. I guess that's the place where you found it.
Nothing tremendous I admit but that's my work anyway, and I would have found a bit more elegant to quote me.
If some need explainations they now where to find me.

voodoodh

Hi dear mr are possible assemble 24 holes hub in 32 holes rim?

JohnnyBeton

Yes, it's possible.
Post your question on my FB group (Bicycle Wheel Building Group) and I could answer more in details.
See you soon

To the admin : sorry for the unfair competition but I am already involved in my FB group (where I am an admin), in addition to some other forum related to bike mechanics. All this is very time demanding and I'd like not to add a new group to my collection.
I'm sure you will understand.