Custom aluminum frame with 2.8kwh capacity

Ratking

1 kW
Joined
May 20, 2010
Messages
494
Location
Norway
Hello,

The time has come to build a commuter bike for commuting around the city I soon move to.
I got some requirements that I want to incorporate to the frame, but nothing is set in stone.

Specs:
-Aluminium frame
-<100v pack so I can use 4410 fets
-Large battery pack build with Enerdel cells
-The biggest hub motor with freewheel I can get my hands on
-If possible, 17" motowheels in aluminum. I want to try mc tires
-All components either downhill specs or stronger
-Power and throttle controlled by CA v3
-Good acceleration and a top speed >80km'h

The basis for the frame is an old Specialized Big Hit. They is some old parts from my other mid drive build and I wanted to recycle them.
The Enerdel cells are large. I really hoped to design a neat and good looking frame, but that did not happend. No way that it was possible to put more than one cell in one plane without making the frame bulky and large. But I wanted a large capacity bike, so I did the best I could.

Weight guesstimate:
Battery, 22s2p, 470g x 44= 20.68kg
Hub motor, commonly around 12 kg with wheel
Complete frame ex rear wheel/motor= 22kg
Total weight=55kg

I hope that I can get the weight below 55kg, but I don't care. I am a big man and I can handle 55kg. I just hope that the bike can handle my 115kg's.

Frame is built with 4mm 5052 aluminum. Easy to weld and can be bent without cracking. I found out that the aluminum was very dirty, so I had problems with getting good welds. I used a lot of gas and time just to heat up the aluminum and get the contamination out.
For the motor I hoped that QS motor could supply me with their 273mm motor, but since they don't reply to mails anymore I wont send them any money before the explain themselves. I am open to any suggestion for a big hub motor with lots of torque.

Below is a couple of pictures of what I did in one session. I think it is possible to make a frame from scratch in one day if you have enough welding gas, food and patience :lol:
 

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Holy smokes :shock: thats alotta work for 1 day,gonna be a great build.
 
beast775 said:
Holy smokes :shock: thats alotta work for 1 day,gonna be a great build.

Thank you. I hope so myself :wink:

I started to calculate what the parts I needed would cost, this is an expensive hobby for sure. Just a good pair of front forks and rear shock is several hundred dollars for the absolute cheapest option. And I need a motor, controller, wheels, tires etc. I need to get a second job...
 
I want to resurrect this project from the dead ;)

I have been busy with other projects this winter and started to collect parts and plans this spring.
I will just trow out some progress pictures as for now and give a better explanation later.

Final spec:

Motor QS 205 4t
Controller Sabvoton 72150
Battery Enerdel 20s 35Ah
Rims: MT-2.5 17" motorcycle(will try tubeless)
Bunch of downhill stuff that I will not bother listing, just the usual

What is pictured is a lot of hours in cleaning and welding etc. Still my welding skills such at aluminum. The parts has to be clean and use the right filler rod etc. I had problems with the types of aluminum/alloy I wanted to join, but as long as it holds together for a while ;)
Due to luck I now have access to a lathe and mill. So this project should now soon be done. I really look forward to feel the power from a QS 205 in a 17" rim. I hope it is not over hyped.
 

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Got some more work done, the main machining and steelwork is done, so I hope to get the wheels lanced soon and try this bike out. The weather got much better, so I would have liked to have the bike done by now :/

I did see something that I don't like, the exit/gap for the phase wires between the drop out and disc brake is too small. What do people do in order to protect the wires from being chewed over by the turning parts and the drop out? I would like a permanent solution, capable of withstanding a few rolls and crashes

The QS hub motor looks nice, I hope it performs well in a 17" rim.
 

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izeman said:
you are CRAZY! i like it :) what alloy did you use? 6xxx or 7xxx? (and please remove the slash between 2.8kW and h in your topic :mrgreen: )
edit: reread the thread. you mention 5052 alloy. so you're mixing 6'alloy and 5'alloy? can you heat treat the frame? or do you just build it stronger?

I am mixing everything ;) I just hope that the frame don't break at the front crown/ head tube. The head tube is extra long and well welded. But I hope it will handle the stress without any heat treatment. Having a front fork with 200mm stroke will take some of the beating of the head tube. The frame is 6mm 5052, mated to 6000 series alloy on the big hit frame, so compared to the orignial thickness I have trippeled the wall thickness. Lets hope that is enough ;)
 
I've chopped a lot of frames - and this is some really cool work. Well done!
 
Cool build for sure. Looking forward to watching it unfold. Nice job!
 
macribs said:
Kool frame. What made you choose those batteries?

Thank you, I got a really good deal. Else I would have chosen the Volt or any other smaller format. To be honest, the frame is a bit bulky for my taste, but it was the only way of getting 20s2p in there ;)
 
multifrag said:
Is it cost effective to use Enerdel cells over 18650s?

If you are lucky enough to get them cheap and you have the space. they are also delivered as OEM and that speaks volume of the quality for me. Less connections is also a big plus
 
After a long break, due to lack of will to measure custom spokes for the back and front wheel, I am finally back :p
This should have been done for several months ago, but it is now bought, delivered and awesome. I did actually measure the right length and the chineese company delivered nice, stainless spokes and nipples for the job.

What I got is two 17"x2.5" super motard rims that will be used with Michelin Pilot sport tires. I want to be able to drive hard and corner like a super motard and not a bike. I had to use super heavy gauge spokes, because of the nipple holes. Spokes are 9G, hope they dont break anything.

Next step is to get the wheel straight, put on some new tires and try them on the bike, can't wait to try the bike out, I feel this bike will be solid and have a large enough battery pack to be useful
 

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I bought a 20 mm front hub with 36 spoke holes, they don't come cheap from Hope. Did not like to bore out the hub for bigger spokes, feels wrong :/
 

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More work has been done, but mostly planning and tinkering around how to safely incorporate a battery pack with enough compression. When I first made the frame I had four 90 degree aluminum angles welded to the frame that was there to hold the cells in t position, but I did not like the design and cut the parts out. That did not go as planned due to an angle grinder doing more work than I wanted :cry: The disk hit the bone and they had to brush and scrape all the particles out of there. Not the best feeling when you can feel metal chew against your bone

What I have decided is to use half the plastic mounts on the Enerdel modules to make them thinner, I don't think it will do any difference regarding safety. I don't have much room to work with, so it must be like this anyway.

I also welded a new bottom bracket in place. The old one was welded with with the left threads on the right side :/
 

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izeman said:
that's a really deep cut. sending shivers down my spine. :(
but the result will be great. i still love those 20Ah cells. they perform so nicely, and are so easy to handle.

It was not that painful before the doctor used a ordinary toothbrush to scrub out the dirt. But that did not help the pain :D I am glad it worked out, because I worked with the wound open for 12h before i went to the hospital. I did not want to ruin a day at the workshop, but in hindsight I should have gone straight there, because the wound can dry up and make it harder to sew and heal. Live and learn

I hope the result will be good, I do feel the plan I have now will secure the batteries in place for good. I want this bike to be a work horse that I can use without any worry for a long time
 
Ratking said:
because I worked with the wound open for 12h before i went to the hospital.

makes me think of the black knight sketch in the monty python's holy grail. Ah tis but a flesh wound.

I think id have downed tools and washed it out, gone and got some pain killers. anyway hope it heals well.
 
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