tube type & newish variability
I've been getting Dankung tubes for about 4 years now. It seems that in recent times tube stiffness has changed. I don't know if this was directed by Dankung to their vendor for a new choice of targeting, or if this represents a loss of control by their tube vendor. Either way, it leaves me not knowing what to order to get the stiffness I expect and want. Here's some history that reflects the stiffness variation. I use tube density (e.g., in grams per inch of length) to reflect stiffness-- e.g., 2 identical bands in parallel will have twice the stiffness (or force) and twice the density. Note that there is not enough accuracy in measuring tube diameters to reflect reproducibility.
1745 tube densities vs. time:
0.3079 (2012), 0.318 (6/2013), 0.3385 (2/2015), 0.3400 (6/2015), 0.3168 (9/2016)
2040 tube densities vs time:
0.247 (6/2013), 0.2336 (2/2015), 0.2019 (7/2016)
2050 tube densities vs time:
0.3981 (6/2013), 0.4049 (6/2013), 0.375 (5/2016).
The last order of (standard) 2040 I received was 20% lower density than previous ones and the pull was so wimpy it was useless to me. 1745 long ago had a density of about 0.31, then it was consistently raised to about 0.34. My last order was back down to about 0.31, and is so weak it seems like a different tube type, and is almost useless to me.
I need more 1745 with density ~0.34. So how do I order this? At some point, companies need to spec their products to both their customers and their vendors. Density is very easy to measure and I hope Dankung will spec it before I'm driven to look at other vendors (until recently I've been very pleased with Dankung).
Don’t be too quick to infer how much faster tapered tubes might be compared to untapered. You need to compare at the same pull force and draw distance (to fork). Whatever setup you choose, if you had double the pull force or draw distance it’s quite likely to be the fastest!