Originally Posted by
Mark Kelly
Having just been through this and replaced all the 288 mm DT alpine III s with 290mm, I'd say round up.
BTW "interested" as far as I can tell everything in your post is wrong. The longer nipples have the same thread length the same distance from the nipple head, it's just the length of the shank that is different (to allow access for the spoke wrench). You cannot compensate for short spokes this way. All you are doing is taking advantage of the fact that there is 8mm of threaded length in the nipple and using less of it.
No I am exactly right. 14 and 16 mm DT Swiss nipples works as I say. This is clearly seen on the cut away photos in Musson book (page 96 in 5th ed.) and is explained in the text too. It can also be deduced from the fact that DT Swiss' own spoke length calculator changes the required spoke length depending on choosing 12, or 14 or 16 mm brass nipples.
Other nipples from eg. Sapim may work as you describe, but not the DT Swiss nipples I explicitly named.
So when using DT Swiss 14 mm nipples, the ideal spoke length is one mm /below/ the nipple slot.
Originally Posted by
Mark Kelly
On DT Alpine IIIs up to 3mm excess length is easily accommodated with standard 12mm x 2mm nipples (I've measured this).
Depending on what you are even talking about here, this is wrong. What I say is that it is commonly accepted that the ideal spoke length to go after, is a spoke length that means the spoke is flush with the nipple slot (assuming standard 12 mm nipples). When the spoke is flush with the slot, that means that the nipple can still turn for a further 1 mm without running out of thread. To put it in another way, by aiming for making the spoke flush with the nipple slot, one has an error margin of +1 mm, or that the spoke can protrude 1 mm above the nipple slot before it starts to crush thread.
What you seem to claim is, that (Alpine III) spokes can easily protrude almost 3 mm above the nipple slot. If so, then you are wrong, since it is a simple fact that every millimeter above the 1 mm error margin means that thread is crushed.
Originally Posted by
Mark Kelly
What Musson etc have ignored is that DT Alpine IIIs are stiffer than comps and using them on the DS with thinner spokes on the NDS reduces the difference between the elastic strain in the spokes on each side. This results in a wheel which is marginally heavier (a little over 10 g for 32H) but stiffer and better balanced.
Jobst Brandt is an engineer that knows what he talks about. Musson's reasons are more practical; after making wheels for e.g. professional Downhill bikers for years with 2.0/1.8 mm spokes (or thinner) his conclusion is that thicker spokes solves no practical real world problems with bicycle wheels. Modern day quality db spokes from Sapim and DT Swiss are so good that people probably die of old age before they ride their spokes to the metal fatigue limit, if the wheel is correctly build and designed to begin with.
So why optimize for features that have no or very little practical meaning, but comes at cost like price, wind resistance, weight, availability in both lengths and at the LBS, incompatibility with many hubs etc.
I know this sound somewhat prattish, but I have reread both my own and your post, and I fail to see where I was wrong, or where you have found anything wrong with what I said.
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Regards