RDY wrote: ↑Wed Nov 09, 2022 12:54 pm
StiffWeenies wrote: ↑Tue Nov 08, 2022 6:23 pm
StiffWeenies wrote: ↑Fri Jul 29, 2022 12:53 pm
I have a feeling that the 290g version is just how the 24mm Ti spindle option will be marketed. There's a 22g difference between the
SRM Origin 24mm Ti (94g) and
30mm Alloy (116g) spindles so a 30g difference for the Elilee doesn't seem too far off once you factor in the 28mm-to-DUB/30mm conversion shim.
Besides, there just isn't enough economies of scale to justify developing two different layups for the carbon arms.
A little update on this
The 24mm Ti axle is now out and it's actually heavier than the 28mm alloy on top of being flexier. Ti axle crankset's sans-PM weight is 340g versus 320g for the alloy.
For those who prefer to run PM pedals over PM spiders, Elilee has come out with 5-arm and 4-arm alloy spiders. The 4-arm alloy spiders also have the option of being able to attach clear decorative covers (~11g) that mimic R9200 and R9100 chainring design language.
Elilee is confirmed to be working on a carbon axle crankset which should come in at a sans-PM weight of approx. 285-290g. There will also be carbon spiders for even more WW goodness (4-arm carbon at ~30g v. 4-arm alloy at ~46g).
It remains to be seen how they can balance weight with stiffness as the main competitor to this carbon axle crankset, the THM Clavicula SE, was revealed to be quite flexy according to Elilee's internal testing:
There are XC cranks coming too:
What's the stiffness measured in? Amount of deflection? Is it replicating a pedaling load or static load? The Ti axle being that much more nominally flexy looks slightly worrisome. Also that it came in that much flexier and also significantly overweight relative to their initial projections (and the Al version) tends to suggest it might not be without problems. It sounds like they could have made a lighter - and certainly stiffer & cheaper - steel one. Surely if the Ti one came in this flexy and overweight it makes sense to junk it.
Interested to see how the MTB one works out.
Are these likely to show up on Ali?
It's measured under a static load on a bare spindle of the pedal. The flexier 24 is not unexpected.
The bending stiffness is roughly proportional to E * (OD^4-ID^4), where E is the young's modulus, if two are similar. Given two pipes with the OD1 = 28, ID1 = 24 (assumed), E1 = 71.7 GPa (7075 T6), and OD2 = 24, E2 = 113.6 GPa (Grade 5 Ti), a same stiffness will call for ID2 =19.8. The density of Ti is 60% higher than Al, and the Ti spindle of XXE 28 is roughly 70 g, so we need a 100 g Al 24 spindle to give a same stiffness based on this simplified model. Their test results of 24 spindle crankset is 77% stiff as the 30 spindle one, so 100 * 77% = 77 g. Sounds like 7 g compensation is enough? However, note that this simplified model doesn't consider the 28>24 reducer, which can induce more flex, you need again to add more weight (material) to the spindle to compensate it, and also add the weight of the reducer itself.
Also, steel spindle won't be both stiffer and lighter, if you want an as stiff steel spindle, it needs to be heavier. In this way, it will be as stiff, heavier, but stronger.