Big Bike Thread
- Thread starter Breamy
- Start date
- Status
I also cant watch the video at the moment but i agree with Supercow.
Weight has an effect on acceleration (and deceleration, as they are the same thing really) but no difference to maintaining speed.
Once you get a wheel moving, it requires the same force to conserve the momentum regardless of weight (assuming same rolling resistance and aerodynamics).
Newton's 2nd Law says that acceleration is equal to the force put in divided by the mass of as object.
So, for the same force put in, an object with less mass has more acceleration.
watch the vid when you get chance but at one point near the start he uses two 'wheels', exactly the same size cylinders, one aluminium and one much heavier (brass I think).He puts them on a 7 degree slope and releases them, the only force acting on them is gravity, so its equal for both cylinders.
Which reaches the bottom first?
Agreed handling will be different but if we are just talking straight line..
Last edited:
I dont think that's correct.
From what i remember from physics at school a long time ago:
Force = mass * gravity
So the force acting on each object is different, but proportional to it's weight (hence 2 objects of different weights move at the same speed).
He puts them on a 7 degree slope and releases them, the only force acting on them is gravity, so its equal for both cylinders.
Which reaches the bottom first?
Agreed handling will be different but if we are just talking straight line..
I literally know nothing other than real life use, but a light wheel helps maintain speed better because it isnt heavier thus causing it to skip across things better than a heavier wheel... If that makes any sense.. Mountain biking isnt a smooth surface so weight surely comes into it across rough terrain?
In an experiment like the one shown all objects will accelerate at the same speed, as long as they have the same frictional resistance and air resistance (same surface area coming into contact with the air).
As the mass of one object is larger, that object will experience a greater force of gravity, but as it has more mass it also requires a greater force to accelerate it, so the two cancel each other out and the acceleration is the same for all objects.
However it DID require a greater force to accelerate, in this experiment that force is provided by gravity, when riding that force is provided by your muscles, so they must work harder on a wheel with more mass.
The experiment is misleading when applying it to cycling.
Edit: Unless we're talking about riding downhill with no pedalling involved at all!
And as others have said the extra mass will affect other aspects also such as increased braking distance (however slight), less agility in air (more mass to move = greater force required) etc.
As the mass of one object is larger, that object will experience a greater force of gravity, but as it has more mass it also requires a greater force to accelerate it, so the two cancel each other out and the acceleration is the same for all objects.
However it DID require a greater force to accelerate, in this experiment that force is provided by gravity, when riding that force is provided by your muscles, so they must work harder on a wheel with more mass.
The experiment is misleading when applying it to cycling.
Edit: Unless we're talking about riding downhill with no pedalling involved at all!
And as others have said the extra mass will affect other aspects also such as increased braking distance (however slight), less agility in air (more mass to move = greater force required) etc.
Last edited:
The really weird part for me was when he used the hollow cylinder, of equal dimensions, both with the ends open and capped so eliminate air resistance, moved slower than the solid one, showing that the distribution of weight played a bigger part - the hollow one moved slower purely because the weight is at the circumference.
If my thinking is correct this means popular opinion is correct that weight saved at the circumference, ie, tube, tyre, rim, is worth far more than weight saved at the hub/axle
If my thinking is correct this means popular opinion is correct that weight saved at the circumference, ie, tube, tyre, rim, is worth far more than weight saved at the hub/axle
You need to be able to do that in the first place :d
You could use a really heavy front wheel to keep the line and stability whilst having a super light rear wheel to kick out
Yes, because as you get further out from the centre the speed the object is moving increases.
Draw a circle around the axle and one around the tyre from a side on view of the wheel, the second circle is much larger (has a greater circumferance).
Therefore any point on the second circle must travel a greater distance than any point on the smaller circle to make one revolution. However it travels this greater distance in the same amount of time, Speed = Distance / Time so any point on the larger circle has a greater speed than any point on the smaller circle.
Again as the time for one revolution on either circle is the same, a greater acceleration must be provided to any point on the larger circle, than any point on the smaller circle, to reach that greater speed in the same time.
Force = Mass x Acceleration. So an increase in mass on an object with greater acceleration is going to require more force than an increase in mass of an object with less acceleration.
I'm at work trying to explain this while hiding my internet usage from colleagues so sorry if that isn't explained very well!
You could use a really heavy front wheel to keep the line and stability whilst having a super light rear wheel to kick out
does that mean you couldnt have a good wheelie and whip setup?
Soldato
- Joined
- 22 Feb 2010
- Posts
- 5,212
- Location
- Southampton
anyone know what the sizes are like on Troy Lee jerseys? order bigger size than normal or order normal size you normally order normally?
does that mean you couldnt have a good wheelie and whip setup?
You need to be able to do that in the first place :d
HAHA, what on god's green earth does that mean?
Define normal? For reference, my normal TLD normally feels normal.
thats why i got the cassette expander, gr8 wheelies yo.
Soldato
- Joined
- 22 Feb 2010
- Posts
- 5,212
- Location
- Southampton
My large troy lee is large... same as my large royal top
helpful (unlike supercow
) i have a royal top so will size match that! normally.
- Status