New frame from scratch

[magna_503]

I"m using sketchup with two frames in my head.
The first frame was planned for as a suspension cruiser hence the long wheel base. My quilbix wheelies at a slight touch of throttle, so I wanted a longer wheel base then the quilbix. This mean that I might more room for batteries. I had 8 6s16ah pack on the top half of the the frame, and 4 6s16ah on the bottom section. When I do decide to commute with it, it'll be a 37miles round trip. So I'm cramming 8 6s16ah in the top section and 4 6s16ah in the botttom. With my luck, cramming 8 6s16ah in the top allows me to place the bottom bracket anywhere below the lower batteries compartment.


The second frame looked a bit cleaner. However, side by sides lipo packs measured 6" long. I might need a wider bottom bracket 170mm fat bike or 208mm bottom brackets for the pedals to clear. Center of gravity looks is also a bit better too for cruising hard.


So far both have not had any mid motor accounted for yet. I still haven't decided if I want mid motor or hub motor. But it wouldn't be too hard to modified the frame or the Farfle swing arm for a mid motor. I might just make another swingarm also.

Let me know if you see any thing that's obviously.

don't worry about the 78deg angle. It's the maximum angle if the bottom tube is parallel to the ground. Most likely it'll tilt toward the ground and reducing the angle ~68 to 72 or so.

 

[Drunkskunk]

Interesting. First, that 78deg. You need to design the frame for the angle it will have when it's being ridden. 78deg is a stunt bike for 10mph or so. Depending on the speed you want, you'll need an angle in the mid 60s to low 70s. First part of your design, the steering angle should not change when you are sitting on the bike. when you go over a bump, the bike needs to remain level and the steering angle should stay the same, regardless of the amount of compression. If it doesn't, the bike will be unstable.

Low center of gravity is great for highly nimble, low speed bikes, like a trials bike. Stability comes from putting the weight up high, and makes a more stable rider, like a touring bike. If you want fast cruising, but nimble handling, you compromise by putting the weight in the middle, like a race bike.

 

[Storapa]

Hi,

As Drunkskunk has mentioned, 78 deg is a bit high. 68 deg is much more agreeable. I managed to package a very large pack (20Ahr @ 72 V) and still run with a standard bottom bracket. My frame is just under 100mm wide.

For my build, packaging took up the most of my time early on in the project.

Good luck with the build.

 

[dogman dan]

You might consider that lengthening the bike means room behind your seat for battery. Unless you have ape arms,, why make it longer in front of the seat?

I have definitely thought of building another of these, but with rear suspension. The batteries are carried plenty low enough to handle great.

 

[magna_503]

Thank you guys for all the recommendation,
I now have 71deg head tube, and still have enough space for at least 9 lipos packs, room for controller and charger in the top compartment, and possibly a mid gear motor in the lower section without batteries. I have no room for EMS at the moment though. I might move the Controller to the top bar and have the charger and BMS in the compartment. Hopefully, everything will work out as plan.

I think I'll have a pretty nice Ebike.

ps. let's see if I can build it as well as I build speakers.