# How to make KERS (Kintetic Energy Recovery System) for 2-wheeler?

I want to make kers for my two wheeler.How should i start and what are the things that i should consider??

Is it an electric two wheeler?

Doug Huffman
Gold Member
Ahh, KERS (capitalized abbreviation) for Kintetic Energy Recovery System.

Consider its required capacity and power (time rate). 100 kg from 50 kph to zero at 1/3 g for a bicycle HPV.

Is it an electric two wheeler?
how does that matter?

how does that matter?

RonL
Gold Member
Not true. The link shows that you can do this with a regular bike and a bit of ingenuity.

http://www.gizmag.com/flywheel-bicycle-regenerative-braking/19532/
That's a great proof of concept, but for a 15 pound flywheel at any significant rpm, the support is just not good (Imho) I say this only to raise awareness for anyone that might just jump up and throw something together :)

timthereaper
I totally agree. It's shows good thinking and it's all mechanical, but I don't quite see the allure of carrying around 15 extra pounds on a bike just to save you maybe 10 percent of the energy you expend. This link is a sexier version of the electric bike conversion kit: https://www.superpedestrian.com/. I think this might be closer to something people might invest in (but I'm not a cyclist).

RonL
Gold Member
I have always liked the Hub Motor for electric, but the idea of flywheel energy storage for take off assist, is high on my list of ideas.
Biggest challenge is, most states have weight and speed limits, which cuts deeply into energy storage density.

Does the OP want a purely mechanical system? If the two wheeler is electric, a simple regen system might be easier.

We still don't know if Op is starting with a gas motorcycle, pedal bike or electric bike. It matters.

berkeman
Mentor
@tdev -- I see you are on the forum today. How about dropping into this thread and letting us know what you are wanting to do... :-)

timthereaper and RonL
I have always liked the Hub Motor for electric, but the idea of flywheel energy storage for take off assist, is high on my list of ideas.
Biggest challenge is, most states have weight and speed limits, which cuts deeply into energy storage density.

Speed limits on how fast the flywheel can turn? I was about to suggest a carbon-fiber flywheel. It's light enough to be worthwhile but you can get that thing to spin up really fast. If there's limits to flywheel speed, then that's out.

RonL
Gold Member
Speed limits on how fast the flywheel can turn? I was about to suggest a carbon-fiber flywheel. It's light enough to be worthwhile but you can get that thing to spin up really fast. If there's limits to flywheel speed, then that's out.
No!, the speed and weight generally apply to electric power and a limit of around 700 watts at the motor.
A properly enclosed flywheel should not draw much restriction other than, if speeds of the flywheel cause control problems related to resistance to lean or turning.

berkeman
Mentor
flywheel cause control problems related to resistance to lean or turning.

Oh Jeeze! I didn't think of that. A spinning flywheel on a bicycle (road or MTB) could be a very bad thing. Maybe if it could gimbal it wouldn't be a problem. But that would make getting energy into and out of the flywheel much more difficult...

RonL
Gold Member
Oh Jeeze! I didn't think of that. A spinning flywheel on a bicycle (road or MTB) could be a very bad thing. Maybe if it could gimbal it wouldn't be a problem. But that would make getting energy into and out of the flywheel much more difficult...
It might be that a second flywheel spinning in the opposite direction would solve most of the problems, however that begins to increase the engineering design efforts of dual input and power take-off applications.

berkeman
Mentor
a second flywheel spinning in the opposite direction

Ah, good idea! :-)

It might be that a second flywheel spinning in the opposite direction would solve most of the problems, however that begins to increase the engineering design efforts of dual input and power take-off applications.

Yeah the engineering would have to be more significant, but you'd have to do some sort of "balanced system" like that to make it work.

RonL
Gold Member
Yeah the engineering would have to be more significant, but you'd have to do some sort of "balanced system" like that to make it work.
Mount one on each side of the frame and there will be little to indicate there are two flywheels, they are rated around 2500 RPM (while making cuts in concrete) the energy storage for a bicycle should be pretty generous. Just a quick thought :)
New they price from $800.00 to as much as$1500.00, on some occasions a concrete contractor will give them away and not bother having them reconditioned.

berkeman
Mentor
I'm not adding no 30 pounds to my bike! :w

RonL
Bystander
Homework Helper
Gold Member
just to save you maybe 10 percent of the energy you expend
"Ten per cent?" This is for some sort of "Hare & Hounds" cross-country, steeplechase obstacle course? Two seconds on the throttle, two seconds on the brakes until you're seasick?

We don't know. It is a secret.

RonL
"Ten per cent?" This is for some sort of "Hare & Hounds" cross-country, steeplechase obstacle course? Two seconds on the throttle, two seconds on the brakes until you're seasick?

Don't quite get what you mean. I haven't done any real number crunching, so 10% was a number I picked out of thin air. I can't imagine a system like this saving more than that amount of energy. Maybe I'm wrong though...it's been known to happen :-)

Bystander
Homework Helper
Gold Member
Don't quite get what you mean.
so 10% was a number I picked out of thin air.
Back of the envelope bookkeeping on recovery systems just for ordinary driving, I couldn't begin to get 5% for "soccer moms" doing "stop and go" all over town, let alone pay for hauling the additional mass necessary for the recovery around.

Back of the envelope bookkeeping on recovery systems just for ordinary driving, I couldn't begin to get 5% for "soccer moms" doing "stop and go" all over town, let alone pay for hauling the additional mass necessary for the recovery around.

Totally agree.