Gravity Bikes combined with H.R. 727?

[safe]

The Electric Gravity Bike?

Gravity Bikes go fast downhill, but they require a car to take the bikes from the bottom of the hill to the top.

H.R. 727 is the national electric bike law (Public Law 107-319, 116 Stat. 2776) that allow a bike with a 750 Watt motor, pedals and a flatland top motor assisted speed of 20 mph to be classified as a bicycle.

Combine the Gravity Bike concept, a big hill, H.R. 727 and you have a complete package.

1. The 750 watt motor can pull you up to the top of the hill.

2. The Gravity Bike styling means you can go as fast as you want downhill since you will be freewheeling and not bound by the 20 mph limit.

3. More weight actually makes a downhill bike go faster.

So in the end it would be a little like skiing in that you more or less use the motor to get you to the top of the hill and then the actual fun is the downhill part.

Comments anyone?

 

[Matt Gruber]

nice try
enjoy 60 days in jail :lol:

 

[v_tach]

HR727 isn't a law, it is a reference to a particular House Resolution during a specific Congress to amend the Code of Federal Regulations. At the very least try and figure out the actual code articles when you are referring to a Federal Law because there are new House Resolutions every year and the numbers are recycled...

House Resolution 727

Commending the 2006-2007 Trinity Christian School girls basketball team; and for other purposes.
WHEREAS, through perseverance and iron determination, the Trinity Christian School girls basketball team has completed another spectacular season, establishing a school record for their amazing 26 game winning streak and posting an overall season record of 28-3; and
WHEREAS, the team soared through the state playoffs and, as a fitting finale to their remarkable 2007 campaign, captured the state title at the Class AA State Championship with a spectacular 50-42 win over Brookwood; and
WHEREAS, the 2006-2007 Trinity Christian School girls basketball team was composed of the following letter-winning athletes: Kami Bass, Jenna Bedingfield, Jessica Cannon, Dorrie Garner, Kristen Greiner, Laine Hobbs, Anna Claire Knight, Bliss McMichael, Katie Mair, Maggie Moses, Abby Ozment, Priya Patel, Kassi Shepherd, and Rachel Wyatt; and
WHEREAS, the phenomenal performance of the team is a clear indication of the outstanding athletic ability, the dedication and hard work, and the unity of purpose and spirit of each member of the team; their superb offensive and defensive talents; and the astute direction of Head Coach Rick Johnson and Assistant Coach Lacey Shepherd; and
WHEREAS, as this magnificent team earned its well-deserved reputation for excellence by performing with courage and precision over months of training and competition, it is abundantly proper to call them champions.
NOW, THEREFORE, BE IT RESOLVED BY THE HOUSE OF REPRESENTATIVES that the members of this body congratulate the Trinity Christian School girls basketball team on winning the GISA Class AA State Championship and extend their sincerest best wishes for future success.
BE IT FURTHER RESOLVED that the Clerk of the House of Representatives is authorized and directed to transmit an appropriate copy of this resolution to Head Coach Rick Johnson.

As long as the bicycle conforms to any other State and Local Codes AND the rider abides to the speed limit downhill as well, your cake.

 

[newbie electric rider]

3) more weight makes a bike go faster? Didn't Galileo dispel that notion with a little experiment at the tower of Pisa?

 

[Lowell]

More weight will go faster downhill, unless the hill is 90 deg.

 

[xyster]

More weight will go faster downhill, unless the hill is 90 deg.

What happens at 90 degrees? How does the bike's mass know the angle it's falling at?

 

[Lowell]

Actually I take that back. In a free fall there could still be differences depending on weight and aero position :lol:

On a normal paved road hill, increasing mass will give a larger thrust vector, all other things being equal. Try coasting down a hill, and then the same hill with a heavy back pack.

 

[newbie electric rider]

a larger thrust vector???

according to Newtons second law of physics
f=m*a
therefore a 100kg ebike times 9.8m/s per second will have a force of 98 n
now a 200 kg ebike times 9.8m/s per second will have a force of 196 n now if we take f divide it by m, we will still get an acceleration of 9.8 m/s per second in both cases.
according to newtons first law of physics
newtons law of inertia could come into effect if both bikes were heading toward each other .
200 kg ebike hitting the 100 kg ebike, head on after a 20 second fall on a equal incline. They would have the same speed, same acceleration, however at the point of impact those 196 newtons would overcome the 98 newtons.

 

[Lock]

HR727 isn't a law, it is a reference to a particular House Resolution during a specific Congress to amend the Code of Federal Regulations. At the very least try and figure out the actual code articles when you are referring to a Federal Law because there are new House Resolutions every year and the numbers are recycled...

Try US Public Law 107-319, 116 Stat. 2776 enacted December
4, 2002.
tks
Lock

 

[safe]

My understanding is that if weight can be added without increasing wind resistance then you would go faster. A heavier weight with the same wind resistance will go faster downhill than a light weight. If adding weight increases wind resistance then this wouldn't be true...

 

[newbie electric rider]

force equals mass times acceleration.
heavier objects do not fall faster than lighter objects,

The only way to make an object fall at a higher rate, is to reduce the forces acting on it

A feather will fall at the same rate as a brick in a vacumn. The Apollo 11 astronauts demonstrated this.
Here on earth the brick falls faster because of friction from the air
The feather reaches its terminal velocity before the brick.

My new tires for my bike, are softer, stickier, rolling resistance= more friction

If I add a wind screen on my bike, slip stream, aerodynamics= less friction
.

 

[fechter]

force equals mass times acceleration.
heavier objects do not fall faster than lighter objects,

This is true only in a vacuum.
In air, a heavier object will have a higher terminal velocity. If I drop a brick and a feather at the same time, the brick will win. Assuming no significant change in rolling resistance (tires and bearings), a heavier bike should win in a gravity race. The idea of terminal velocity applies to gravity racers.

 

[safe]

The idea of terminal velocity applies to gravity racers.

I read somewhere that people in the "Gravity Bike" world woke up and realized that the heaviest guys always seemed to go faster. After doing some math they arrived at some kind of formula for how weight effects terminal velocity on a bike. (and in the future they are going to provide ballast to the light riders to equal things out)

So on the uphills you want to be light.

On a downhill you want to be heavy.

For wind resistance reasons you always want to have a small volume that is aerodynamic.

Case in point... when my master link fell off yesterday I had to coast down my favorite downhill to get home. My coasting speed was 38 mph which is not that much slower than my best running speed of 49 - 52 mph.

 

[newbie electric rider]

Case in Point.......
Now try it, with no batteries and a lighter rider

 

[safe]

Case in Point.......
Now try it, with no batteries and a lighter rider

Well, this isn't scientific, but there was a bicyclist riding down the hill at the same time and he did not pedal or use the brakes to the best of my knowledge. (the guy was well ahead of me) I passed him at the bottom at about 5-10 mph faster than he was going. Now my bike is more aerodynamic and heavier and probably better serviced and with properly inflated tires so I had all the advantages and it's possible that the guy used his brakes, but I did pass him really fast so the preliminary results seem to confirm the theory....

 

[newbie electric rider]

hehehehe, those are not preliminary results :lol:
It would be a neat idea, to compare the difference between a light bike, and a heavier bike. You would have to get upto terminal velocity to actually see a difference though.
Then compare a faired bike, between a non faired bike, just using gravity for both experiments.
My room mate was mentioning he saw a experiment on myth busters comparing a viper against a toy car using gravity. In that experiment they accelerated equally. The toy car would have less wind resistance though
This is a little off topic, but last year I lost 10 lbs, I was amazed at how much easier, and faster I could go on my road bike. It felt like I was turbocharged.