The wheelbuilding thread

[junfeng]

Hi chaps! It's been awhile since I last posted anything here. Please pardon me for my disappearance.

I'm at the midst of building up my upcoming bike for 2014 and I desperately need help with the spoke length. I'm planning to use Tune Mig 70 & Mag 170 20 hole front & rear, radial front and rear non-DS and 2 cross for the rear DS. The rims it'll be running on is the 20mm carbon tubulars from Planet-X with ERD of 599mm. This should come down to a neat sub-900 grams with DT Revolution Spokes.

Do let me know what your thoughts are. I'm weighing in at 74kg and I don't think it will be much of an issue. Many thanks in advance!

[synthesis]

Drive side would be 295 mm, non drive side 280 mm. Front 282 mm. hope that helps. As always I would recommend spoke washers and nipple washers too. If you chose to use nipple washers the spokes should be 1 mm longer, and a small tip, when you start to tighten up the rear wheel concentrate on the drive side first to bring that up to maximum tension, then the non drive side. IT´s easier that way to get the wheel to max. tension.

[legs 11]

I would never suggest a 20/20h wheel build. Can't see the point of the ratio.......over engineered front wheel and an under engineered rear?
Rear wheels will almost always require more spokes than a front (especially if you intend to use the same rims both front and rear)

[WMW]

That rim needs 28r...

[synthesis]

So when you buy a Zipp or any other wheelset that is 16/20 spoke, it fails?

[legs 11]

No, you shouldn't be comparing a factory zipp wheelset with the wheelbuild proposed here. It's just not the same rim.
20/20h makes no sense to me........and as Ron has said 20h is way to low spoke count for these rims.
20/28 would be good for at 74kg rider weight.
20h won't last.

[jooo]

So when you buy a Zipp or any other wheelset that is 16/20 spoke, it fails?

This is exactly the point WMW and legs 11 are making, the rear needs a higher spoke count because it's handicapped by the drive side flange offset.

Most of the pre-built wheels using that 20mm rim at least have a 24h rear drilling for good reason.

[legs 11]

Exactly, the rear has to deal with the flange offset, plus it has to deal with drive torque coming from the cassette as well. Having an equal spoke count front and rear makes no sense to me, unless it's for a very cheap training set up using an inexpensive rim and hub combo where you might not get much choice with drillings etc.
As we've gone over so many times on this thread, it's not about spoke counts or rim depth or any stand alone characteristics. It's about the combination of parts, building design and technique.
Low spoke counts require a rim that resists lateral forces and can contain high spoke tensions. Most of the very low spoke count wheels
(Alloy Shamal etc. require a rim like a piece of tank armour...lol) but it's the only way to contain such high spoke tensions without constant problems with nipple pull through.
Bracing angle is a big deal as well, and given the ever increasing width of cassettes it has meant that over the years the ratio of spoke front to rear has need to become more extreme. The obvious solution in my eyes is to spec different rims for front and rear (an area where a few builders have moved towards)
In my eyes the whole low spoke count concept has become a bit of a joke. I get people bringing wheels in all the time with broken spokes and wrecked rims, they simply don't have enough strength in their wheels for their rider weight in the majority of situations.
Don't skimp on spoke count.

[bm0p700f]

I would agree and different rims front and rear would be nice if there were matching rims. The only ones that spring to mind are the Kinlin XR270 and XR-300 they at least look the same.

I am not in favour of rasing spoke tension for low spoke count builds as it serves little purpose 1200N DS rear is enough, so long as the NDS rear tensions are even fatigue has not been a problem in my builds. However if hubs with low tension balance are used higher spoke counts or very stiff rims are needed. High spoke tension just mean cracked rims in the long run I see that often on Easton wheels. It is done so flex to the NDS rear will not the spokes on that side to loose tension and the nipples to unwind.

If the components for a build are properly selected then the wheel will be stable without running very high tensions. The wheel I built with this planet X rim was 24H and I used Sapim Race spokes on Tune 170 hubs. That was for a 75kg rider. He supplied the rim and hubs so these are the spokes I picked. A 24 spoke rear on a deeper rim would be O.K on a shallow rim it can work but it depends on the rider.

Hub bracing angles are almost negleted and they should not be.

I wonder how long it will be before we see 24 spoke disc brake road wheels and being marketed as a good idea.

[kavitator]

60mm rim on good geometry hub is 20 spokes enough for rear wheel - i am 82kg and wheel is solid stiff

50mm must have 20 front and 24 rear

low profile aluminium at least 28

[WMW]

So when you buy a Zipp or any other wheelset that is 16/20 spoke, it fails?

Does Zipp make any wheels with a 20mm tall 250g rim? No. Does Enve, Reynolds, or any other big manufacturer you can think of? No. And that is regardless of spoke count. Only their deep heavy rims have 20r.

Large and heavier rims are much stiffer and stronger both vertically and laterally... so you don't need as many spokes.

[bm0p700f]

This why the 16H DA 7700 hubs I have will be paired to 80mm deep carbon rims and only as a limited mileage TT wheelset. Go with the above advise please. That wheel I built for the customer who supplied parts was not with parts I picked for him. If had I would have ordered up a 28H low profile carbon tub rim. They can be ordered.

[zed]

mike t's site is horrible and dated. Free, sure. To build a great durable wheel you need balanced tension. His credo is all you need is a spoke wrench and nothin more. Whatever. Modern materials demand precision. There is no room for guessing. And his crap about flange hole offset is misinformation. The flange diameter input for spoke length calculation, a mathematical calculation uses the PCD, not the total flange diameter.

[zed]

I'm with WmW and Zen... muss on is decent. schraner is dated, opinionated and misinformed and complicates lacing technique. Musson's book is decent and recent with a revision just published. I Agee, Ric's WheelFanatyk web site is a good source of thoughtful information, and he manufactures my favourite tensiometer. There is something of a culture of lore in wheel building that in the 21st century has no place, in my view. Jobst Brandt's book is a must read to if anything explain lacing in an easy repeatable way without counting spoke holes for various crossings.

[bm0p700f]

I have always used Schraner lacing method. I do not have to count spoke holes any more I just know where the spoke go. Far simpler method in my view than the other. The other books I have never read as I worked out all the details for myself by thinking about the physics of a wheel. I am sure other folk can do this for themselves too. If you work out what works from base principles then lore well you won't have any of that. I sometimes get asked to tie and solder as that make a stiffer wheel..... lore.