rabbitt

Lately i've been imagining wild new vehicles, none of which could probably work. But I did learn about torsion springs and immediately i thought "wouldn't it be cool to have a torsion spring on a bike that you can charge by pedaling, then release it for hyper speed?! (hyper speed meaning 30 on a DF and possibly 30-40 on a bent). Has anyone else thought of this? I'm sure there are problems, so all you technically inclined people, now's your chance to burst my bubble. Let me know what you think!

vik 

How about instead of pedalling to charge it you use downhill braking or I guess any braking force to charge the the spring? That could give you a nice little kick when you needed it.

The problem with this idea - like so many other cycling "improvements" is figuring out if the benefits out weigh the cost, weight and added complexity.

jeff-o

I'm sure it would run like clockwork.

BlazingPedals

lol - would that be the second hand or the hour hand?

jeff-o

It all depends on what gear ratio you're using!

Shaman

Since springs are made of steel, the weight would be counter productive. In many ways it makes sense to harness lost energy such as braking energy for controlled release. I would put it in the catagory of constant power cycling where you wind the spring with peddling but the price would be lag time from pedal to motion. You'd definitely need a one way lock device or you'll be holding the spring back with your legs at every red light and stop sign. It would also harness that wasted high torque start energy and use it more effectively. I doubt that you''ll be capturing enough energy to make it up a steep incline. Along with this concept lies its other partner, the gyro, but that's another story

scottogo

use a natural spring

rabbitt

what do you mean by that?

WorldPax

Springs can be made of many things. I believe the rear leaf spring on the new Corvette's is made of carbon fiber.

airxxxwolf

I already do those speeds on my lowracer....without a spring.......

Don

jeff-o

Same on my trike, though I call it "gravity assist."

eubi

I'm guessing you are talking about a torsion bar type spring?

They work OK for auto suspensions, but they have a limited travel.

bkaapcke

Whew! No more weed for rabbitt. bk

GeezerGeek

What is important is the amount of energy stored versus the weight versus the efficiency of converting the energy twice. The cost and safety of the mechanisms can prohibit mass production. Springs store energy by strain. They have a very high weight to energy ratio so they are not practical. If you want to store strain energy in a torsion spring, rubber bands have a far better energy to weight ratio than steel but watch out when they break.

A flywheel that is hooped shaped running extremely fast in a vacuum can store a lot of energy for its weight. If designed right, this has one of the highest energy density to weight ratios of mechanical gizmos.

Bikes have tubes. These are built in pressure vessels that can store compressed air if they are sealed. This is virtually a free storage system that would add little to the weight of the bike. The problem is that compressors and expanders are not very efficient.

I think that people are working on hybrid electric bikes that store energy as chemical energy in batteries. In a few years you will pobably see hybrid bikes using ultracapacitors instead of batteries.

Of course, the highest stored energy to weight is nuclear energy.

Dr.Deltron

That's great! I guess I'll have to dig through my computer for the pics of a Rasta guy who came to town about 6-7 months ago. He was riding a 650 lb mobile home bicycle! It used to be around 800 lbs when he had the bathroom attached. I'm not kidding about this. The vehicle had only 2 wheels but the driveline consisted of something like 7 deraileurs and a flywheel. The rear wheel was a car wheel and the front was from a moped. He could make this thing go like 20 mph over almost any terrain. He wanted to modify my Greenspeed tandem to have this set-up. (no way, Jose!)
But I must admit, his rig did cause me to think more about such an application.
I'll post some pics (probably sometime AFTER Christmas)