By that you mean alphafly next. Just to be clear.
Salvitore Stitchmo wrote:
Weight is still the easiest quantitative metric when it comes to running economy/efficiency of a shoe. 100 grams is equivalent to 1%. The adios is 235g and the Vapes are 195g. So in lab conditions the nxt% has a 0.40% advantage already.
The remaining factors/drivers of economy are
1) the resiliency (rebound effect/"energy return") of the foam
2) the curvature of the plate (and how much the foam allows you to "drop" forwards into that curvature when you strike) which creates the forwards promotion of your center of mass and changes the force vector of your foot strike
3) The ability of the midsole in general to compress as quickly as possible and allow maximum force transfer to the surface you are running on
4) reduction in work of your MTP and ankle joints due to the rigidity of the midsole (created by the plate - same logic as used in spikes for the last um, 50 years)
That's your golden 5 factors of running economy with respect to footwear.
I weighed them - my vaporfly size 9 is 187 grams. The alpha fly size 9 is 214 grams - so 27 grams heavier. However, the stack height on the alpha fly is insane, so much more foam and when you wear them you can literally feel them bounce you. It’s a significantly different feel than the vaporfly. If that bounce is the resiliency, there is a lot more of it in the Alphafly, a lot more.
You could run in socks and argue you’d save 200 grams per shoe and start off 2% more efficient... but then all the other factors you mentioned. Is there a study comparing the two shoes? I haven’t done a race in either shoe due to cancellations, but in training runs the bounce of the alphafly is pretty crazy and subjectively hard for me not to believe the Alphafly is giving me more energy return and propelling me along more than the vaporfly. I can’t do a blind test because it’s impossible to not feel the difference of the Alphafly and so no idea of the bounce is giving me a placebo effect with lower heart rate at same pace and less soreness after long pace efforts. I am genuinely interested to read an actual study comparing the two shoes.
Makin it CLAP' wrote:
Translation - OP cannot afford Alphafly's so they must be bad.
I have Next % and Alphafly's. The Alphafly's are more bouncy, durable and have better energy return.
I've done lots of workouts in the Alphaflys and ultimately decided to stick with the Next% for my recent marathon. I doubt you have scientifically measured your "energy return" in each shoe.
The Alphafly is way more stable under video analysis, anything shorter than a marathon the Vaporfly is likely faster
Though Adidas has always been heavier than Nike but pre Vaporfly they were faster.