Opinions on this frame modification for big battery electric bike?!

[bakaneko]

So, I think I finally found a bike, in this COVID-19 era, that isn't completely trash or has a 300% mark up. And, it is a fat tire bike that I always wanted to have due to the look and grip on the road. I am going for a 2-4kwH big battery hoping to get 120 miles at 30 mph and 200 miles with peddle assist. That being said, I will need to modify the frame. However, I do not know how to weld and I don't think I can learn and do a good enough job for those welds to resist the forces of high speed ebike.

I was thinking about doing something like this. Cutting the top tube and using T and 90D eelbow plumbing steel elbows and pipes to create a frame to enclose around the battery across the top tube. The battery will rest on the bottom tube. The dimensions for the battery is going to be 14.5x7x4 for 2kwH and then 14.5x7x8 for 4kwH. I think with the 4kwH it might have to be mounted higher to avoid leg/peddle strike or I have to get a wide peddles cranks, which means I cant do a mid drive. So, it might be 2kwH = mid drive/hub and 4kwH = hub drive only.

Thoughts? Is this gonna fall apart when Im ridng LUL. I'll make a mock up with cardboard against my road bike soon.

 

[B Bassett]

So, I think I finally...

So you're going to buy a bike that needs modification before you even ride it? Better buy two just in case.

 

[FurryOnTheInside]

I think the downtube wants to be the one that makes the majority of room.
I see the point about the BB, being able to get up to a 120mm BB shell still doesnt make room to pedal around an 8" battery!
I think your whole front end might have to come forward several inches to move the battery forward, away from the BB & seat tube.
You've got to spread your legs around it so it might as well be moved forward a bit from your crotch!

I would LOVE to have a few inches long box extension on my "Mammoth " fatbike frame as I transform it into the 50SAND build project, with a new, longer, head tube further forward on the front.
Hardest bit would probably be finding the steel head tube made for a custom bicycle frame builder, and the facing and reaming it to fit the 1&1/8" semi-integrated headset standard cups. These days custom-frame-building head tubes and other custom bicycle tubing supplies are pretty rare, I discovered looking for a head tube on the internet lol.
The pro cycling peeps don't use steel frames anymore.

 

[bakaneko]

So you're going to buy a bike that needs modification before you even ride it? Better buy two just in case.

Measured twice, cut once - my friend. Its at minimum a 2kwH battery. At 4kwH, its gonna be 50lbs. I'll buy just one and McGuyver it to hell if I f*** up.

I think the downtube wants to be the one that makes the majority of room.

That is a good point about bottom tube, and I wont have to mess with the gear change and rear brake cables too. The only concern is if the bottom tube bears the most force or the top. I rather not cut and modify the tube that takes the most force. Yeah, 7" will be a lot but if it is a 4" wheel I mean that is only 1.5" on each side. That won't look too weird (2" with box).

The thing is I need to decide to buy one or two (4kWH) batteries at the same time or I might not get two matching ones down the road. There is something about 4kWh and a 100 mile minimum ebike (30 mph, no pedal) though that feels like an achievement. Hey, SpaceX and Elon just achieve a crazy achievement; gives me inspiration to just DO IT!

On same note, I've been harping about it for too long. A bit of a hiccup, with corona and no bikes at Walmart, but I seem to find a decent one. Ill make the mockup on Monday and buy the bike Sunday or Monday. I already mocked up one battery (2kWH) and its no problem with normal pedal cranks. I just need to look at the 4kWH size. Because of the steel elbows, Ts, and pipe that I will paint, I think it looks like the Kawasaki H2R or KTM Duke 390. I am not sure which coloring I will go for though I do like a white painted bike too in which case I will design after a Tesla 3.

 

[B Bassett]

Measured twice, cut once - my friend. Its at minimum a 2kwH battery. At 4kwH, its gonna be 50lbs. I'll buy just one and McGuyver it to hell if I f*** up.

That's one way to do it. What..... ah, are you going to do with it? Short day rides?

 

[bakaneko]

pick up chicks with it... no, I will take it to work commutes (10 miles), fishing at lakes around me (30 miles), ride to northern wisconsin scenic areas (100-200 miles). I will take it to FullyCharged Live (EV show) hopefully in 2021 and have a manufacturing system down at that point.

But, I always wanted to bike across the USA. I do road biking too and am decent but I get tired after 40 miles. I've went 160 miles in one day before on a 500W ebike so with this bike I should be able to do 150 miles and have a lot of extra time to relax at end of day. Of course, this means the bike has to be extremely weather resistant.

 

[FurryOnTheInside]

Its a high tensile steel frame. The possibilities are endless for a good fabricator- welder.

The steel 90° elbows sounds like a wonderful idea! ☝ I have not seen any, that i recall.
You want to get as much as possible of the cutting and bending and butting and lapping and making it all fit, out of the way before you bring it to a local independent self-employed welder who has the skills to put it together permanently, with any small fabs that you couldn't do at home (e.g. for heating it to bend it equipment or labour skills, manual dexterity, health and safety, illness reasons etc. that you don't need to specify here.)

Sounds so familiar to me, in fact sounds exactly like my tuned pipe dreams since beginning the hobby, and now my 50SAND build project. ☺
I am going to have to ask (I hate asking!) for some minor fab' on my frame and pipe, which I am not confident about letting someone else do lol, but you have to trust your own local fabber welder (get to know him a little?) and let him go to work on your beloved bicycle baby.

 

[Wrench]

So, I think I finally found a bike, in this COVID-19 era, that isn't completely trash or has a 300% mark up. And, it is a fat tire bike that I always wanted to have due to the look and grip on the road. I am going for a 2-4kwH big battery hoping to get 120 miles at 30 mph and 200 miles with peddle assist. That being said, I will need to modify the frame. However, I do not know how to weld and I don't think I can learn and do a good enough job for those welds to resist the forces of high speed ebike.

I was thinking about doing something like this. Cutting the top tube and using T and 90D eelbow plumbing steel elbows and pipes to create a frame to enclose around the battery across the top tube. The battery will rest on the bottom tube. The dimensions for the battery is going to be 14.5x7x4 for 2kwH and then 14.5x7x8 for 4kwH. I think with the 4kwH it might have to be mounted higher to avoid leg/peddle strike or I have to get a wide peddles cranks, which means I cant do a mid drive. So, it might be 2kwH = mid drive/hub and 4kwH = hub drive only.

Thoughts? Is this gonna fall apart when Im ridng LUL. I'll make a mock up with cardboard against my road bike soon.

If your gonna cut and weld that frame ya better know how to Tig weld I suggest you have an experienced tig welder weld that frame
Not a welding job for a rookie.

 

[B Bassett]

pick up chicks with it... no, I will take it to work commutes (10 miles), fishing at lakes around me (30 miles), ride to northern wisconsin scenic areas (100-200 miles). I will take it to FullyCharged Live (EV show) hopefully in 2021 and have a manufacturing system down at that point.

But, I always wanted to bike across the USA. I do road biking too and am decent but I get tired after 40 miles. I've went 160 miles in one day before on a 500W ebike so with this bike I should be able to do 150 miles and have a lot of extra time to relax at end of day. Of course, this means the bike has to be extremely weather resistant.

And licensed. You're talking a Class-3 ebike or possibly even in the emoped category for various States. Regardless you can't ride it on most biking infrastructure or State or National parks. Why the overly large/heavy battery? Also, are you planning on carrying any gear or just throw it into a backpack? Gonna need a charger at the minimum, and I always suggest some fenders, headlight, tail-light, bar-bag at the least, GPS, control interface for the motor, controller unless you use a BaFang mid-drive, tools (home and on the bike), pump(s) ah.. but those are tools. Couple sets of brake pads, few chains, pray that you get the seat right on the 1st guess let alone the bars you are going to need. The ability to carry min. of 2L of water and a great water filter for 150-mile rides. If you are worried about the bike being water-resistant then that means you will have to be as resistant. Of course, you are going to have a good smart-phone and plan... cameras are nice too, helps me remember the actual individual rides. Do you have a guess of what speed you plan on riding at? Duration?

 

[FurryOnTheInside]

Watt meter carrying, licence checking, predatory pigs, that seem to terrorise the imagination of the mentally traumatised, are not in reality the most common hazard on a cycle path, or the 30mph roads that electric cyclists like to use as their routes.

The pig tend to just look for flashy hatchback cars that are popular with materialistic people, who are the main culprits of acquisitive crimes, such as trading in "controlled" substances.
Even the worst of bored and opportunist pig tend to ignore innocent cycle tourists cycling silently by with their overloaded bicycles. Especially because they can see we are smiling and sitting up enjoying the countryside.
They do not carry out electrical checks.
They do not carry electrical equipment to test with.
They are not qualified electricians.
They have no interest whatsoever in the pedal equipped bicycle you are riding if you appear to be acting normally and sensibly for a cyclist.
Like most predators the pig has a tendency to chase only when he sees the prey panicked or especially vulnerable.

Oh yeah you do need a battery charger for an electric bike. I am sure glad that was pointed out before it was too late!
Not sure about the water filtering system but I don't live in Outer Mongolia anymore.
The battery capacity we are discussing building a bike under is probably enough to get its rider to a point of sale like a gas station so he can buy some bottled spring water.

Its fine. Worst comes to worst, you put a holographic sticker on it. The exact actual same sticker, not a substitute or counterfeit sticker, it is the same sticker as sold by the company that makes the motors of all different wattages.
Be sticker legal and ride normally. We dont go at 30mph down the pedestrianised high street and up the front steps of the Porkhouse, crashing into their arrivals desk.
You'll be okay if you just keep your cool. They cant tell you're human if you just act like another zombie sheep.
I cant promise. I have a feeling that you might not keep your cool, feel compelled to confess your sins, with every unnecessary sentence (no need for speaking while cycling anyway).

Try not to say: " I'm a wattages vandal! I over-volt! I hyper-amp! Im a disgusting over-clocker! A legislative limit busting fiend from the depths of hell! I use too much electricity and I need to be punished into total submissionnnn!!!"