Coming along nicely...

[tombenn444]

Hey there everyone been riding ebikes for about a year now been riding and building motorcycles and motorbikes for over a decade this is my first homebrew ebike build. 72v 3000w Amazon motor. Homemade (if that's not obvious) 72v battery just took it on its first ride today. Not far just a block. Besides just showing off I was wondering if anybody out there would be so kind as to criticize my work maybe some tips from people who know more than I do. And yes I am aware it has only one pedal. Thanks all

 

[neptronix]

You asked for criticism, so..

Here's my off the cuff take:

I'd say less duct tape and better battery holding would improve the build.
Think about a smaller rear wheel to get a better reduction and positioning of the motor..
Think about modifying the frame as little as possible in order to get a motor like this mounted.. also, if you're willing to build a 2 stage reduction you could have used a 2lbs maytech RC motor instead and fit it behind the rear wheel.

I've ridden a 60mph electric bike once but i'd be scared to ride this at a fourth the speed, based on how it looks.

 

[tombenn444]

That's fair and I agree with everything you're saying that I understand. I chose this bike because of frame-shaped I think would be able to hold the battery at a good low center of gravity. I had to chop off the seat stays because of chain contacting I wasn't going for anything specific this is just the only thing that would work with what I had I had other frames but none of them seem like it would be as easy as what this is become. And totally right about the duct tape I plan on soon upgrading to zip ties

But anyway

The sprocket had to be welded onto a brake disc mount for it to attached to the rear wheel and as you can see I have a bunji cord with a tensioner from a motorized bicycle keeping it tight and it SEEMS like it's doing all right. I'm not arguing a thing that you're telling me, just telling the story. But thank you very much for the critisism it will be put to good use

 

[gromike]

Vaya con dios.

 

[neptronix]

A mounting position on the lower bar of the bike's triangle will give you better center of gravity, the closer to the middle of both axles, the better.

In general i wouldn't advise weakening the structure of a bike frame because they're built for pedal power to begin with and don't come with an excess of strength to handle ebike duty. That's what would worry me about your bike more than the appearance.

 

[E-HP]

The battery clearance to the suspension fork could be a safety considerations when running. Try lying the bike on its sides to check what will impact the ground in the event of a crash, and adjust accordingly. Crashing sucks, but adding a battery fire on top of that would suck more. E-bikes are like motorcycles, in that it’s not if you go down, but when.

 

[Cryingmadman]

The battery clearance to the suspension fork could be a safety considerations when running. Try lying the bike on its sides to check what will impact the ground in the event of a crash, and adjust accordingly. Crashing sucks, but adding a battery fire on top of that would suck more. E-bikes are like motorcycles, in that it’s not if you go down, but when.

I have a suggestion for a name for your bike when you christen it with that korbel sparkling wine.

“El peligroso”

Regards

Cryingmadman

“Ideas are easy Execution is a Bitch”
Marie Antoinette

 

[raylo32]

=:O

 

[tombenn444]

Yeah I don't really like the clearance between the battery and the front wheel either maybe if I were to dip the back into the battery lower it will let me bring it closer to the rear wheel. Or just swallow my pride and Mount it on top of the frame instead. But as far as everyone's concerned about the structural integrity of the bike that's actually the least of my worries I'm not a welder but I do know how to weld and besides even new bikes got welded somewhere. Probably end up welding up a third set of front forks. For good measure. Unfortunately it seems my guardian angel is blessed me with a bit of electrical failure because I'm not getting any response from it today I think it's the whole sensor in the throttle.

 

[tombenn444]

Hey everyone here's an update on my build, criticism appreciated. Since my last pictures I swapped out the duct tape battery mount with a steel cradle I swapped the chain over to a bicycle chain I modified the rear sprocket with a track guide made from a brake disc and I added brakes to the rear

 

[marka-ee]

I'm familiar with that motor. That's the BLDC motor that they sell in different wattages. I have that also. Did you drill out the small holes to allow more air to go inside? With the gear ratio you have on that motor, I'm imagining you're not near its optimum RPMs. What kind of temperature does the motor get to and how fast does it go?

 

[Az.]

I hope your suspension doesn't work.

 

[tombenn444]

Lmao it does I just haven't shaved down the edge of the battery case yet. I took it out for a test ride yesterday and it having a bicycle chain probably didn't help it but it was going good for a while until it ripped out three of my spokes. So I'm going to have to construct another rear wheel I've since upgraded to a fatter chain and sprocket I'm thinking about just constructing an entirely new rear end. Hell I'm thinking about just constructing a frame it'll have space for my battery and my motor and be adjustable and I don't have to try and make something already made work. That happens a lot with my projects it seems to be that I get almost done with it I find a flaw and I completely just tear it apart start over

 

[Az.]

I don't think rebuilding half of it will change much. It looks like a proper deathtrap. Better buy a ready made e-bike.

 

[tombenn444]

I don't think rebuilding half of it will change much. It looks like a proper deathtrap. Better buy a ready made e-bike.

Does this bike really look like it was built by someone who can afford to buy an ebike

 

[Az.]

Buy a second hand bike and convert it using hub motor. I guess you can't afford good health insurance either. You have only one life. Don't throw it away.

 

[slitespd]

All I can say is, if the Wright Bros had started this way we wouldn’t be flying!

As has been said over the years, duct tape can fix anything!! This bikes fixed for good

 

[Chalo]

I can convert an existing bike right now, not 72V 3000W but a more practical and supportable 36V 350W, for less than $200 in parts. Motor and battery (ready to install) are salvaged, so they're better quality than cheap new parts. The resulting bike could be built to 750W class and near 30mph for a couple dozen dollars more and some intensive battery finagling, but I wouldn't ask for more than that for the motor's sake. Also for the bike's sake, if I were starting with a crappy department store donor bike.

My old hub motor wheel deal is no longer available, but Battery Clearing House has some cheap second life wheels back in stock for about $30 more than before.

 

[tombenn444]

Okay third update during my test rides I kept throwing chains so I've upgraded the chain to a I think it's a #30 chain. I cut slots into my motor mount so it would be adjustable I chopped off the rear end completely because I wasn't happy with it because it wasn't symmetrical and rebuilt it. Kept having trouble with the bearings failing on me and my last wheel got three of the spokes ripped out whenever the chain got caught up in them so with my new (to me) wheel I've attached a concrete saw blade to act as a chain guard. Might put something on the other side of the sprocket too might not havent decided yet. Upgraded the axle to a half inch piece of all thread slapped a couple of caged ball bearings in there. Works great spins smooth no wobble I just have to modify where the axle locks into the bike might thicken it a little bit idk. I'm not a welder but I know how to weld.

 

[tombenn444]

Buy a second hand bike and convert it using hub motor. I guess you can't afford good health insurance either. You have only one life. Don't throw it away.

And that is why nobody will remember your name

 

[Az.]

And that is why nobody will remember your name

I might regret it, but would you kindly elaborate? Why nobody will remember my name?

 

[Chalo]

As opposed to the name "that crackpot guy who got killed on his homemade garbage bike"? It's not a great name to be remembered by.

 

[marvin78]

I am not a fabricator per see, the last time I touched a welder and made something useful has been decades ago.

But just between you and me, @tombenn444 , I wouldn't be down to ride this bike. And I'm fairly risk tolerant, but those are not good welds.

I'm not a welder but I know how to weld.

I think you know how to pile up molten metal at roughly the spot you think it should, hoping it will 'glue' the materials you're trying to join. But, judging from the pictures, I would not claim you know how to weld.

Which is fine, I mean you're the one going to ride it. But don't act surprised if people act in doubt of this being 'safe'.

I would be very thoughtful about the amount of heat you're putting into that frame, and how much this heat cycle will affect the material properties right around the edges of your joints ( = brittle ). With how much material being left in some places, as I said I don't think I would ride it even as acoustic bike let alone when you're going to put actual power through it.

 

[tombenn444]

Almost done. Seat, chainring, and handlebar grips.

 

[rafalg]

Mad Max