Building the best commuter ebike (ever)

[auraslip]

In this thread I will document my latest high powered ebike build. This should take a few months as my time and funding allows.

Goals:
30 mile range at 30 to 40 mph.
50 mph top speed
Water proof/theft proof design
Integrated charger
Professional quality looks!



Frame: 23" specialized hardrock disc - the only components I'll keep stock is the drive train.

This frame has a massive triangle with room for a massive battery pack. Unfortunately, it is also REALLY tall so I'll need to run 20" wheels as well as run a shorter stem to bring the handle bars closer to me.

Another problem is that the frame is curved which should make it a bit harder to make a wooden battery box. Instead of the typical 3 pieces of 1/2" wood planks I may need to use multiple cuts of wood. I'd like to be able to plan this all out in sketchup, but I'm not sure how to accurately import a drawing of the frame.

Another issue is what sort of wood to use? In the past I've used whatever was cheapest. Is there anything better than what the local Lowes carries? Perhaps 1/2" or 3/8? wood? 1/4" is too small to drill in to for mounting.

EDIT: I ditched the hard rock and went with this frame

 

[miuan]

20" wheels and 23" frame? To me that won't look like a bicycle anymore.

 

[rojitor]

Your "integrated charger" goal has all my attention. Subscribed

 

[Jason27]

50 mph you will need at a battery of at least 72 volts, and a motor above 1kw. It wont be classified as a bicycle anymore. You would also have to wire a ton of lipo together.

Are you willing to spend $2k?

 

[veloman]

50mph on an aluminum hardtail? Maybe your roads are smooth as glass.....

Why do you want 20" wheels? Do you really need to oversize the frame that much to get all your battery on it?

 

[MadRhino]

20" wheels and 23" frame? To me that won't look like a bicycle anymore.

+1

Looking forward to see how you can achieve professional look with that. :wink:

 

[auraslip]

My last build for reference -> https://sites.google.com/site/shelbyelectro/Bike-of-the-week/12---kiyohime

It cruises at 45 mph. The only problem I have with it is that the battery pack is quite anemic at 22s2p and there isn't room for more! Also, the 9c motor quickly overheats. And bumps in the road suck on a hardtail. I'm hoping the 20" moped tires and the longer wheel base will help with that.

I'd love a full suspension bike, but until I learn how to weld my own I'm not going to find a FS frame that fits my needs. And yes, I'm aware how little this will look like a bicycle.

 

[veloman]

Moped tire should help. In my experience though, unless you run low psi, even the big wide tires ride harsh over bumps with a hub motor.

 

[bc_dc]

For the battery pack holder you could use strips/thin planks of balsa and steam them so that you can bend them into shape. Then wrap a layer or 2 of fiber glass or carbon fiber around the balsa to add strength and stiffness and still be very light. You could also go with the styrafoam core fiberglass/carbon fiber route; even melting out the foam with gasoline to leave a cf shell.


Has anyone split the batteries into 2 locations when they couldn't all fit in one? I would think that as long as the connections are good it should work just fine.

 

[neptronix]

Yeah, i've done the split..
some batteries in a rack, some in a falconEV triangle bag.. just make sure the wires hookin' it all up are nice and fat so that you don't get series/parallel current imbalance.

 

[dogman dan]

Time to learn to make your own plywood. Thin strips of wood or even paneling can bend easy. So you glue them up, put into a jig the shape you need, then use wood screws to hold it till the glue dries. Viola, curved 1/2 inch plywood.

Another alternative would be to kerf a regular boad many times on the inside radius, bend it, then glass the whole thing.

 

[JohnC]

For the battery pack holder you could use strips/thin planks of balsa and steam them so that you can bend them into shape. Then wrap a layer or 2 of fiber glass or carbon fiber around the balsa to add strength and stiffness and still be very light...

I’ve got balsa planks that I'll donate to the cause.

 

[auraslip]

I love this forum! You guys take DIY to a whole new level.

I'd love to see dogman the master carpenter make a wood box in my style. He'd probably blow me away. Of course you like to check and handle each pack after use so the box would have to have hinges on it so it could be opened easily.

I may take you up on balsa for the side panels. They can be as thin as I can find.

 

[auraslip]

Wow, it does look like a clown bike with 20" BMX wheels. The stand over height is perfect though. The pedal is resting on the floor. I'll have to cut the pedals down to 1/3rd the size and tap them out.

The OD of the wheel is exactly 20" with the tires being 1.5" tall. This means if I run a 2.5" moped tire it should 1" taller making the OD" of the wheel near 22". Hopefully this will keep it from looking wonky.

 

[shock]

what if you run a 26 on the front and a 20 on the rear? Just put a good thick 20" tire on there. Would likely prevent having to cut down the crank arms.

 

[auraslip]

what if you run a 26 on the front and a 20 on the rear? Just put a good thick 20" tire on there. Would likely prevent having to cut down the crank arms.

It would really mess up the handling.

Right now I may have found a good source of 17" motorcycle rims for real cheap.

 

[auraslip]

also I got my extra long BB from sick bike parts today. I can easily fit 4s pack sideways which means even in a smaller frame I can easily stack LOTS of batteries all the way down to the cranks. Maybe I should find a smaller frame?

wonder how it will effect the chain angle though?

 

[liveforphysics]

50 mph you will need at a battery of at least 72 volts, and a motor above 1kw. It wont be classified as a bicycle anymore. You would also have to wire a ton of lipo together.

Are you willing to spend $2k?

Dont have sex. You could get messy, may need a shower, could cost dinner, risk of babies.


Don't drive racecars. You will have to spend a lot of time hauling stuff to the track, putting gear on, its going to cost at least $500 for a track day entry, your car might break or get wrecked.


Dont get a dirtbike. Most of the places you want to go have roads that get there. You will most often ride around and end up back at your dirtbike hauling vehicle where you started.



Life is about the experience. Nothing, truly nothing else on earth matters.
Embrace the experiences you desire. Ripping on a fast ebike is a killer experience.

 

[auraslip]

Look at stevil_knevil's lovely bike rocking 17" wheels and 3" moped tires. OD is ~23" - perfect.

Oh and he has these wheels for sale @ $50 each -> http://endless-sphere.com/forums/viewtopic.php?f=31&t=35066#p510830

I've never laced up a hub motor. I wonder how hard it'd be to lace up a magic pie or larger scooter motor?

I've also found one of these in an XL on ebay:

It's cheap - steel - and has much better drop outs for mounting racks + torque arm. Also it has a kickstand plate.

 

[dogman dan]

Easy, once you have the right spokes. Practice lacing with old junk wheels if you never did it before.

 

[JohnC]

With respect to the Stevil pic, I also like how he created a useable space between the frame and seat post to mount his controller. Nice.

 

[auraslip]

ack - i'm getting lost in analysis paralysis.

The more I read up on potential hub motors to use the more I become convinced that scooter hub motors are the way to go since they're cheap and readily available. I'm talking like a 3kw rated hub motor for $400 shipped compared to a cromotor for twice the price. Or a 6kw hub for $600 shipped. DAMN.

Only problem is they are typically 190mm rear spacing (compared to standard 135mm rear spacing for mtn bikes or 150mm rear spacing for some DH bikes)

So I'd pretty much have to make or HEAVILY modify a frame to fit the motor which is out of my scope of skills, tools, and budget. Farfle's gensis swing arm looks promising, but the frame triangle itself is quite small for anything but a racing battery pack.

Looks like I may have to plan for a smaller magic pie - see how that fairs and then upgrade to a x5 or cromotor at a later date.

 

[auraslip]

Well I guess I'm getting the gunnar frame. http://www.ebay.com/itm/Gunnar-Rock-Tour-21-Touring-frame-/220959721307?pt=Mountain_Bikes&hash=item337239c75b

Hope it works out well.

 

[auraslip]

Folks on the ES FB group told me not to get the gunnar frame. I think no one likes it because it don't look cool or fast. I agree. But this is for a dorky looking, but practical mid-level moped / ebike.

My other options were aluminum DH frames or aluminum FS frames. Both of which were expensive, complicated, and lacked room in the triangle for chargers, batteries, electronics, etc, etc.

Handling wise a FS frame would be great for rough roads. I agree. It sucks that I can't find a decent FS frame that fits my needs at the current time. But this is a tradeoff I have to accept.

Safety wise I'm thinking that a good quality cro-mo frame will hold up better than a low end FS aluminum frame. Some of those swing arms look a bit janky for higher speeds. I've heard of people having problems with excessive sway and horizontal stiffness. Most bikes are made for light riders, carrying no loads, at slow speeds. I'm not a small guy, and I'll be carrying 60lbs of gear + wtvr is in my bags at the time.

Sorry I'm rambling. I just needed to justify to myself this build before I really get into it. I was tempted to scrap it, and find a high performance FS frame..... but practical > performance for me.

So I should have the frame soon, and I'll start making the box. It should be simple now that I know enough trig to figure out the angles.

One thing I want to do for this bike is rig the keyswitch to start ALL the systems: cell-logs, temp sensors, controller. And then have them all in a plastic case mounted to the bars. This should be a nice build, so bear with me over the next few months as it falls into place.

 

[Arlo1]

The integrated charger thing has me thinking about. How we would use the brushless controller to rectify AC to charge our batteries.... HMMMM