Building a 60mph electric motorcycle on a 26" bicycle frame

[3wheels1life]

Hi everyone,

Do you have any suggestions for building a hub motor powered electric motorcycle on a 26" bike frame?
Legally, it wouldn't be an e-bike. I'd like it to go 60mph.
Any advice you have is appreciated.

-3wheels1life

 

[torker]

You will hear this ..... Bad ,bad, really bad idea to go 60 mph. on a bicycle. Mod a motorcycle if you want to go that fast.

 

[MadRhino]

I do it everyday and soon hit 20 000 miles on one of my bikes.
All my bikes but one are doing 60 + Mph, and 2 of them would be happy to ride above 100 Mph.

Build on a Pro DH racing frame, build with the best components and wheels.
You need 100v hot, an 18 fet controller modded to 150A batt, and a cromotor in a 24" wheel. Big wires, big connectors.
Ideally, use a 3" DH tire on the back (eg: Duro razorback or Wildlife Leopard), and a 2.7 on the front (eg: kenda Nevegal).
Enjoy, but be careful at first try for it will be able do do a back flip on a start

 

[friendly1uk]

It will break. It would be great if motorcycles with that performance could be as light as a bicycle, but it would just fall apart.

You would have such weight on board, carrying so much kinetic energy, that a pot hole would trash your wheels. Just a bit of fatigue each time, till one day, Your running at 60mph with the remains of a cycle between your legs. If it is not the wheels it will be something else. There just not designed to do it. IIRC an alloy frame has a limited lifetime anyway, your going to limit it even more carrying more weight at higher average speeds. Cracked frames are not uncommon on commuters cycles used as intended.

You could do it for a bit though. The issue is how long. You know your building a motorcycle, and you know what they should look like. You may not have an engine, but your motor and batteries pose just the same stresses. They would all be more minimalist if they could be safely

 

[MadRhino]

It will break. It would be great if motorcycles with that performance could be as light as a bicycle, but it would just fall apart.

Motorcycles carry the weight of a big gas engine, big steel frame, heavy transmission, heavy wheels and brakes, and gas tank. Yet, most are not as a good ride as a DH racing bike. Of course there is maintenance and inspection do do methodically, but I ride my bikes hard off road for years and never had a dramatic failure on any of them. I ride half the weight of a pro trial motorcycle, I don't have as much torque but close enough to climb any hill, and a much higher top speed.

 

[Samd]

It's interesting to see that a lot of the old forum members have dropped off, and a lot of the more recent members are still handing out very old advice. People still make a big deal in other threads of old and outdated myths such as hub gears failing, yada yada.

I'm listening to you MadRhino and ignoring the copy/paste advice otherwise - the fact that you are actually doing it reliably matters. With quality components.
How many watt hours are you carrying? I'm mindful that batteries need scaling up with speed and that is the potential weight trap.

Cheers.

 

[neptronix]

Start with a motorcycle. There's no way you won't have legal problems going those speeds, even if you manage to put something together that doesn't kill you.

No current bicycle hub motor is capable of doing that speed sustained.

 

[LSBW]

Im surprised even admins are chiming in.
Subject was discussed at length before, there's even a wiki article: http://endless-sphere.com/w/index.php/I'm_a_Noob_and_I_Wanna_Go_50MPH

 

[tomtom123]

imo, it seems very dangerous to even do this . a car going 20mph hits a bicyclist going 15mph and the cyclist has a chance of dying, now going 60mph, that's scary. but who cares what i think, i'm just a noob without an ebike....yet...

 

[MadRhino]

I am carrying 500+ Wh packs, each that are weighting 7.5 Lbs (3 X 8s 5800 mah Zippy compact). Only one pack to ride the mountain trails (rides that are never more than 10 miles since my longest trail is 6 miles up and 3 miles down), sometimes two in town if I need to ride out of my commute, it happened a few times that I had carried as much as four to go riding the suburbs.

I agree that 60 mph is not to be sustained for a long time with a hub motor build. Yet, if you carry less than 1 kwh of battery capacity, you are unlikely to fry a big hub within your available range, unless you deliberately run it way out of its efficiency zone. For longer rides, you need to ease some sections to let it cool, so temp monitoring is a good idea.

I agree also that it is dangerous, but not more dangerous than riding a motorcycle at the same speed. Most of the time, I believe it is safer because it has better handling and shorter braking distance than any dirt motorcycle that I've had. Some windy days though, I feel it is too light weight for the speed that it rides. Then, building to ride 60 Mph on a wallbike is playing Russian roulette. You need to build a bike that is able to do that speed comfortably, with proper balance and geometry, stiff and sound, equipped with adequate brake and suspension components, and consciously maintained in perfect order. This kind of toy is not for the distracted and unconscious rider, but it is real fun in the hands of one who knows what he does.

 

[torker]

Have not heard back from the OP . Maybe we scared him off I hope not. Is it me ? Seems like I have seen a lot of new members popping up. Most lurk a while then jump in. Maybe it is all of the new production machines available.

Any rate he got some good answers. MadRhino hit it right. Use the best quality DH frame available. I guess tires and aluminum frame would be the two things that would scare me some. Although the bikes on his sig. fit the bill if you want to go fast on a bicycle.

 

[dogman dan]

I agree. If you will do it, do it the way Mad Rhino does. I bet his forks cost more than my entire off road bike, motor, and battery.

Components aside, you are screwed going that fast with cheap full suspension frames. They are just too floppy to go the distance. They flex and flex, and actually get softer like the way a ski wears out.

But if you start with a frame built to stand a 30 foot huck to a flat landing, then bolt on top notch shocks etc, It's quite possible to ride that fast without the bike falling apart or getting the tank slappers.

And of course, it's been well demonstrated on the racetrack that even the cheap stuff can hold up for a day or two at least. Most of the stuff that came to the track the same day I was there was in the "disposable after one day" sort of category. That's quite different than riding it for years.

If you look closely at a Zero motorcycle, it's more or less a very strong frame, with the most rugged possible quality bike grade stuff bolted on. Rims might be motorcycle type, but they slashed the weight compared to typical motorcycle stuff.

One of the better efforts at a "bike" frame with pedals to do this with is the Greyborg.

How you dress, and what the cops may think of your "60 mph bike" is your own decision to make.

 

[3wheels1life]

Thanks to everyone who replied and gave advice.

So I guess I can't use a Raleigh steel bike frame for this one, eh?
How much would a 60mph build like this cost?

Thanks so much.

-3wheels1life

 

[neptronix]

Lol
Are you trolling us or what?
Trying to find someone who will give you advice to make something super mega illegal so you can use it as bad publicity against the ebike community?

This thread is your first post - are you for real?

http://lmgtfy.com/?q=electric+motorcycle+forum

 

[3wheels1life]

These people built something on a bike frame that goes super fast. http://www.electricbike.com/10-fastest-electric-bikes/
This design is not for the street. I thought the steel frame was strong enough for a hub motor.

Sorry I offended you.

-3wheels1life

 

[neptronix]

The people who have built these bikes are experts and have many years of experience. You will notice that these bikes are either custom frames, have custom rear swingarms, or are made with very expensive downhill bike frames.

These people started out with slower and simpler bikes, and gradually learned how to build things like this; they did not immediately build 60mph bikes with 0 experience.

Start small, and if you can't flex on the 60mph requirement, just go with a motorcycle. They are designed to go that speed.

 

[wesnewell]

Don't be discouraged. With ~$2000 you can build a 60mph bike. It may fall apart with the first pothole you hit at that speed, but so what. You won't skid to far. With 24s lipo this motor kit should do it.
http://www.alibaba.com/product-gs/1138310936/High_power_3000w_electric_bike_conversion.html

 

[SHARKBITEATTACK]

How about a 2wd bike? More power and not as much heat

 

[cal3thousand]

How about a 2wd bike? More power and not as much heat

Looking at the previous posts, I find that issue here is with safety at that speed, not overheating motors. John in CR does some insane speeds on a single rear hub motor.

That 2nd motor is just adding complexity and more unsprung weight.

Anyone thinking of attempting this better take MadRhino's and Neptronix's advice. ONLY the best components, well maintained with the proper knowledge/experience to back it up. If you don't have the skills or the time, buy an electric motorcycle.

I've been riding and building ebikes for a couple years now and I STILL wouldn't put my bike up to 60mph speeds. My fast build (DH;18FET;24S) is only targeted slightly above 40mph. And I have the sense to understand that the 40mph is only for bursts and that I will cruise around 30mph.

Question for the OP:

What's the highest speed you've ever fallen off of a bike? Think about it and answer it honestly (even if just to yourself).

 

[speedmd]

What's the highest speed you've ever fallen off of a bike

Does that include a motor bike Been there on all types.

I want to build a super fast ultralight 700c ebike. Smooth roads only. Full on, w/ friction brakes, light 25mm road tires /clincher wheels, tt clip on bar set up. Max 40 pounds.

And yes, I am wanting 60 PLUS. Seriously. Will fatten up the tires only if I absolutely have to. Just want to see how it will climb. Will keep it in the garage on windy days for certain.

 

[Dauntless]

I have this little test you can run that will allow you to demonstrate to all your detractors that you will be perfectly safe on your little bike at 60mph. Make a video of this test and post it here, so they know there's no point in arguing with you.

What you do is take an aluminum can, stand it on one end, then stand on it. It should support your weight. Unless there's some little imperfection in the side, if there is just get another or another until you find one that stands up. Be careful not to wiggle your foot or reach down and lightly tap the side or anything that could make it buckle.

There, this video will prove that in a perfect world you'll be perfectly safe on your bike at 60mph. If you leave in all the crunches up to the point where one finally worked, we'll probably find the video quite entertaining, as a matter of fact.

 

[neptronix]

Wonderful point ---^

 

[Chalo]

You'll need about 12hp to hold 60mph, not counting whatever extra amount you might want to accelerate to that speed in a reasonable amount of time. Bicycles are built to withstand a steady 1/2 horsepower or so, with occasional momentary bursts of up to a couple of hp.

So say you have an economy car with a 100hp engine, but you want to take it to Bonneville and try for 300mph, and you need 2000hp. Do you think your car will hold up? Because that's what you're talking about doing with your bicycle.

Just use a motorcycle. That's what they are for. Even MadRhino would have had an easier and much cheaper experience if he'd started with a 125cc motocross bike instead of a pretend-motocrosser DH bike.

 

[speedmd]

I see your paying attention. Just because it is not for everyone, does not change the math.
http://kreuzotter.de/english/espeed.htm


My weight and a 45-50 pound bike requires just over 4kw to push 60 MPH when holding the drops. Clip on bars is faster/less safe certainly.

take an aluminum can

Funny one. What is the safety factor in this example. 0.1-.2 or so with my weight possibly if you have good hard thick aluminum can. With Chalo..... :lol: :lol:

What is the safety factor in a standard road frame. Varies certainly, but take a more recent 3.5 pound steel racing frame (happen to have a few hanging around collecting dust). With 160 pound rider, and 25-30 pounds of added (motor/battery) weight, we are still well over a 1.5 safety factor. Smoother roads will not be a issue that would reasonably be a concern for frame failures. Aluminum frame, possibly 1.25 SF. Forks / steerer tube would be a week link in the classic 1" size. Newer 1.125 / 1.5" fork steerer setup would be better. Also suitable would be a heavier large tubed carbon frame, but the failure mode is a bit concerning. :|

I will pass on the sewup/ friction brake setup. :lol:

 

[speedmd]

So say you have an economy car with a 100hp engine, but you want to take it to Bonneville and try for 300mph, and you need 2000hp. Do you think your car will hold up?

1000 hp! Clearly set the record / won the race! Does not have to last any longer but does so easily.

If I can Sprint 34-35 mph on the pedal bike, 60 would be less than twice that not some three times the speed. 50mph is not a issue on a twisty mountain downhill road so all hell is not going to break out at a few higher.