Why do faster rollerblades have five wheels?

[NeoPTLD]

Since each wheel have rolling resistance, how does adding the fifth wheel reduce rolling resistance?

Also, there are some people with the center two wheels removed. Does that increase or decrease the drag? Why so?

 

[konichiwa]

No idea but longer skis are faster too, so...:beer:

 

[Citation]

good question, i have always wondered this as well.

 

[IEatChildren]

Each wheel you add reduces the weight on each of the others.
200 lbs on 4 wheels is 50 lbs on each. 200 lbs on 5 wheels is 40 lbs on each.

 

[IEatChildren]

Each wheel you add reduces the weight on each of the others.
200 lbs on 4 wheels is 50 lbs on each. 200 lbs on 5 wheels is 40 lbs on each.

 

[TheNinja]

b/c your body weight is spread out over 5 points of contact/wheels and not just 4. B/c of this, the wheels have less drag, so instead of the 4 wheels sinking into the ground and having a lot of the wheel touching the ground at the same time, the 5 wheels don't compress quit as much, therefore a little less of the wheel is touching and there is a little less drag on each wheel.........honestly it sounds good to me but I really have no idea

 

[Crazymofo]

Staley8 is on track and it also adds stability when traveling at higher speeds.

 

[Fiveohhh]

Originally posted by: Staley8
b/c your body weight is spread out over 5 points of contact/wheels and not just 4. B/c of this, the wheels have less drag, so instead of the 4 wheels sinking into the ground and having a lot of the wheel touching the ground at the same time, the 5 wheels don't compress quit as much, therefore a little less of the wheel is touching and there is a little less drag on each wheel.........honestly it sounds good to me but I really have no idea

I thought there was a post here a while ago kinda like this except regarding car tires and it was established that doesn't matter the size of the contact or how many tires a car had, the friction was the same... didn't matter how much contact area as long as the material was the same, and the weight..

 

[NeoPTLD]

Originally posted by: Staley8
b/c your body weight is spread out over 5 points of contact/wheels and not just 4. B/c of this, the wheels have less drag, so instead of the 4 wheels sinking into the ground and having a lot of the wheel touching the ground at the same time, the 5 wheels don't compress quit as much, therefore a little less of the wheel is touching and there is a little less drag on each wheel.........honestly it sounds good to me but I really have no idea

Each wheel will carry less load, but there's an additional wheel, therefore total weight is the same and if each wheel had a same frictional loss, there will be greater loss.

To equal or go below the loss of four wheel skates, loss(joules per sec) at each wheel must be 1/(1.25 or more).

Longer blade length means more arc length to effective maximize your thrust and you can achieve this by increasing the gap between each wheel instead of adding more.

 

[Beau]

Originally posted by: Staley8
b/c your body weight is spread out over 5 points of contact/wheels and not just 4. B/c of this, the wheels have less drag, so instead of the 4 wheels sinking into the ground and having a lot of the wheel touching the ground at the same time, the 5 wheels don't compress quit as much, therefore a little less of the wheel is touching and there is a little less drag on each wheel.........honestly it sounds good to me but I really have no idea

i'm by far not a physics major... but all things being equal, wouldn't the drag be exactly the same reguardless of how many points of contact? It would all average out, and if anything be detrimental in that there is actually more surface area in contact/points rubbing to slow down.

AFAIK the only advantage to a larger skate is it's weight distribution adds to the stability.

I'm probably wrong... like I said, I have no clue

 

[NeoPTLD]

Originally posted by: Beau

Originally posted by: Staley8
b/c your body weight is spread out over 5 points of contact/wheels and not just 4. B/c of this, the wheels have less drag, so instead of the 4 wheels sinking into the ground and having a lot of the wheel touching the ground at the same time, the 5 wheels don't compress quit as much, therefore a little less of the wheel is touching and there is a little less drag on each wheel.........honestly it sounds good to me but I really have no idea

i'm by far not a physics major... but all things being equal, wouldn't the drag be exactly the same reguardless of how many points of contact? It would all average out, and if anything be detrimental in that there is actually more surface area in contact/points rubbing to slow down.

AFAIK the only advantage to a larger skate is it's weight distribution adds to the stability.

I'm probably wrong... like I said, I have no clue

Have you tried to spin a rollerblade wheel? It slows down real fast because of viscosity drag from bearing grease. This is pretty much a fixed drag and each wheel you add, you add this drag.

BTW, if your wheel spins really fast and keep on spinning for a long time when you free spin it, your bearing is likely out of tolerance and even though it seems to be very effective, it will probably have a lot of loss under load.

 

[opticalmace]

seems like it would just be for stability, since the friction between the wheels and the surface is negligible; the wheels are rotating at the same speed as the surface is moving by

just like how olympic skaters have REALLY long ice skates.

maybe i'm wrong, but i think it's mainly for stability at higher speeds, with better quality components, reducing weight etc

 

[Fiveohhh]

I'd say a longer skate gives you better stability and not much more, thats my uneducated opinion though. I don't see how it would give you a bigger arc in your stroke your leg only extends so far no matter how many wheels you have on your skate..

 

[TheNinja]

My only analgy is think of putting a 200lb object (say a large box) onto 1 round wheel/ball. Then push it, it would be hard because that one ball has to take all of the weight so it can't roll as well. Now put that same box onto a platform that has 25 wheels/balls under it. It would push very easy now......dang it has been too long since I took physics.

 

[Fiveohhh]

Originally posted by: Staley8
My only analgy is think of putting a 200lb object (say a large box) onto 1 round wheel/ball. Then push it, it would be hard because that one ball has to take all of the weight so it can't roll as well. Now put that same box onto a platform that has 25 wheels/balls under it. It would push very easy now......dang it has been too long since I took physics.

That depends on the surfaces if both surfaces were solid, and you can balance the load I believe that no matter how many balls you had under your load it would take the same amount of force to move it. if you did it in sand, than surface area would matter since your going to sink in, but if they were both solid.....

 

[NeoPTLD]

Roadbikes have narrower tires than mountain bikes and electric cars have narrower tires than a Ferrari.

What that means is narrower tires have have more weight per square inch, yet they're chose in favor of wider tires to minimize drag.

I don't think you can increase the mileage of a Honda Insight by putting a 275mm width tires even though that will decrease the amount of load per square inch.

 

[Fiveohhh]

Originally posted by: NeoPTLD
Roadbikes have narrower tires than mountain bikes and electric cars have narrower tires than a Ferrari.

What that means is narrower tires have have more weight per square inch, yet they're chose in favor of wider tires to minimize drag.

I don't think you can increase the mileage of a Honda Insight by putting a 275mm width tires even though that will decrease the amount of load per square inch.

Nor will you reduce the milage of the car by putting wider tires on it.... It doesn't matter how wide your tires are, you still going to have the same coefficient if the same load is forcing down and the material is the same.. Wider tires in a ferrari are chosen for stability not because you get more traction. narrow tires are chosen in economy cars cause they are economic(cheaper)..

 

[Ciber]

The extra wheel is to increase the length of the frame. By increasing the length, they increase stability at higher speeds. The skates also use bigger, harder wheels. The longer frame also helps you put more power into the ground.

 

[Dacalo]

More stability

 

[Eli]

You ask the strangest questions.

That isn't a bad thing though. People that actually think are somewhat unique in this world, it seems...

 

[Howard]

Know what clap skates are?