Court and Eddie,
Thanks for the input. Always good to have constructive discussion that is beneficial for all.
I think that is how one learns. One of my favorite Prof used to encourage students to probe more and understand it fully before accepting anything. He would say, " If you ask, you are a fool for 15 mins, but if you don't ask, you're a fool for life." So, there is no teacher / student situation here, but it is a collective group and shared knowledge. With google a click away, one can learn things really fast.
Coming back, formula
momentum=mass*velocity (p=mv) is used for
explaining a lot of linear motion and more on that here.
A heavier item doesn't fall more quickly, that's right. But the static inertia of a bare spring and loaded spring are different because of the mass. If we consider the suspension as a spring,
there is something called Hooke's law. If you look at the compression and elongation curve on that page, it can explain the difference between a hard tail and a FSP. While a hard tail has nothing like rebound, FSP has much better traction. So, important not mix up physics concepts. A spring with a mass attached at the end stretches longer and moves quickly compared to a static spring.
A neat video from Khan academy:
Now, the jumper may not have the traction of a non-electric FSP bike but it's better than any hard tail electric bike for traction on any rugged surfaces. I am a flat footed person and have been a long distance runner. So, my area of contact is much higher than normal feet and hence lesser speed. Now, if I carry 5lb dumbbells on each hand and run (trying to equate it to hub motor scenario), of course I will have more mass, more momentum and better traction.
So, if the reverse cycle of rebound (elongation after compression) is held back by a suspension, doesn't the extra weight acting on the hub create more downward force? (Newton's law conserved here, Hooke's law) and get the wheel to touch the ground quicker? The pedal bob depends on the terrain and speed as well
Some excellent animations from GT Suspension. Fox has some excellent designs as well.
I will distill the question to this point:
- Imagine a jumper without a hub motor
- and now add the weight of hub motor to the same jumper
What's the effect of adding more weight on the wheel? is it going to affect the rebound, if so, how?
Why is the traction reduced? because the suspension always to stay in stretched state not in compressed state.