Building a Bicycle with Mechanical Regenerative Braking

In summary, the conversation revolves around the feasibility of using a spiral spring as a regenerative braking system for a bicycle. There is a discussion about the potential weight and complexity of such a system and the possibility of using a generator-battery-motor set instead. The concept of using a constant force spring is also mentioned, with suggestions to calculate the energy storage and potential use for climbing hills. It is eventually suggested that using an electric motor/generator and battery may be a more practical option.
  • #1
ambush_xx
4
0
I am planning to build a bicycle with mechanical regenerative braking. I am thinking of setting a spiral spring to wind during braking and use its tension to assist in climbing hills

Would such a spring give me enough power for this? Are there any other alternatives?
Is this feasible??
Any info or tip would be appreciated.
 
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  • #2
It's definitely possible, but I suspect that the additional weight of the necessary 'clockwork' mechanism would outweigh any benefits you might gain.
 
  • #3
i don't really see more than a few Kgs of additional weight from the 'clockworks', but can the spiral gear serve my porpose.
 
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  • #4
Welcome to PF, Ambush.
Even if you keep the weight down, the sticky part that I can foresee is in the mechanical complexity. If your riding conditions were exactly the same all of the time, it wouldn't be a problem. What troubles me is how you would set up the power-management system so that it both absorbs and releases the energy at rates that are suitable for different situations.
For instance, my town lies at the junction of three 8° grade highways that are over a km long each. You'd need a spring a metre in diameter to do any good here. Even someplace like San Fransisco has so many different lengths and grades to its streets that getting a 'generic' system to suit all of them seems quite daunting.
There's also the matter of how it would interact with your gear train.
As Brewnog said, it's very doable. Practicality, though...?
It might be worth sacrificing some weight issues and installing a small generator-battery-motor set. It would be easier to regulate.
 
  • #5
I really don't need it to be practical, its just a project for school. Just a working model for demonstration purpose would do fine..
 
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  • #6
Oh... that's different, then.
If practicality isn't an issue, then you can definitely make one that will work to some extent. You'd need some sort of reversing mechanism, since a spring releases its energy in the opposite direction to which it was absorbed from, plus a 'neutral' to keep it out of the way in level riding.
Good luck with it. Keep us informed of your progress.
 
  • #7
Hi ambush,
The type of spring you're referring to is called a "constant force spring" also called "constant torque spring" and "negator spring". All you need to do to show the effectiveness of such a project (in principal) is to calculate the amount of energy stored in a given spring, and relate that to the amount of energy you might be able to store during a typical braking application. If you size a spring that might do this, then compare the size and weight of that spring to what you believe is practical.

It might also be nice to see if the amount of energy stored for a spring could be used to augment the power needed to climb hills or something like that. I'd imagine being able to store up some energy while peddling along flat ground by applying the brake for example, then using that energy to help climb a hill.

Here's a website that sells these springs. They might have all the information you're looking for.
http://www.vulcanspring.com/mechanical/conf.html
 
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  • #8
Will try that out...Thanks..
 
  • #9
Q_Goest said:
It might also be nice to see if the amount of energy stored for a spring could be used to augment the power needed to climb hills or something like that. I'd imagine being able to store up some energy while peddling along flat ground by applying the brake for example, then using that energy to help climb a hill.

You can do that calc without worrying about the energy storage mechanism itself.

Ignoring air resistance etc, the KE that you can store when the bike stops = (1/2)mv^2. The energy needed to climb a hill of height h = mgh.

Play with those numbers and decide if your idea is going to work.

A more practical option might be to store the energy decelerating from speed V down to 0, and use it to help you accelerate on the level back up to speed V. That could be useful for cycling in cities. An electric motor/generator and a battery might be more practical than a spring. But Google for inventor Clive Sinclair in the UK to see how not to make money out of this idea. The Sinclair C-5 wasn't exactly a commercial success, and his second try at power-assisted bikes was even worse.
 
  • #10
It's too late for me to edit my previous post, so I'm just entering this as a correction for a typo. The highways leading to my town are 8 percent grades, not 8 degrees.
 

Related to Building a Bicycle with Mechanical Regenerative Braking

1. How does mechanical regenerative braking work on a bicycle?

Mechanical regenerative braking on a bicycle works by using a special braking system that converts the kinetic energy of the bicycle into electrical energy. This energy is then stored in a battery or capacitor, which can be used to power the bicycle's motor or other electronic components.

2. What are the benefits of using mechanical regenerative braking on a bicycle?

The main benefit of using mechanical regenerative braking on a bicycle is that it allows for more efficient energy usage. By converting the kinetic energy of the bicycle into electrical energy, it can be reused instead of being wasted as heat. This can lead to longer battery life and a more sustainable mode of transportation.

3. Are there any downsides to using mechanical regenerative braking on a bicycle?

One potential downside of using mechanical regenerative braking on a bicycle is the added weight and complexity of the braking system. This can make the bicycle heavier and more expensive. Additionally, the regenerative braking may not be as effective in wet or slippery conditions, so traditional brakes may still be needed.

4. Can mechanical regenerative braking be added to any bicycle?

In theory, mechanical regenerative braking can be added to any bicycle, but it may require some modifications and specialized components. It is important to consult with a professional or do thorough research before attempting to add this system to your bicycle.

5. How does mechanical regenerative braking compare to other forms of regenerative braking?

Mechanical regenerative braking is one of the most common forms of regenerative braking, along with electrodynamic and hydraulic regenerative braking. Each type has its own advantages and disadvantages, but mechanical regenerative braking is often preferred for its simplicity and reliability.

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