My humble take on E-bike design and contruction

[wallemannen]

Hello to all E-bike freaks out there!

I´m a swede, a furniture carpenter and a amature designer with E-bike dreams and poor english!
I have sneaked around in this forum for a while and you guys are the greatest! It´s a massive amout of amazing machines to drool over in here!
so after a while of drooling i decided to build my own bike, the real build has not started yet, but the design is more or less done.
of course there will be alot of rethinking and redesigning when the build is taking form but this is my main plan!

the idea is to build it out of 22 mm mild steel tubing ( becouse that is what i have 80 meters of all ready)
wheel size is 24 inch, and a mid mounted hubmotor.

here is what i got so far. (The model is not very high detailed and there are som pretty "sketchy" parts so bare with me)

I would really like if you guys with a little more experience in building E-bikes say what you think and tell me if there is some horrible misstakes in the design!
and when you are at it, please give me tips for a good motor-controller-battery setup.
/Walle

 

[wallemannen]

I did not manage to up load the pictures....

trying again!

 

[Kepler]

Love the design. very nice render too. The only thing that looks wrong to me is the pedal position. I think a cruiser needs the pedal postion to be more forward.

 

[wallemannen]

thanks for the reply!
I see your point with the pedal position, but I don't really go for a cruiser style, I aim for a more racing style seating position. A sort of cafe racer style.

 

[kudos]

Hejsan!

I love the design you got there, I agree the pedals need to be more forward, or you could leave them there but put some foot pegs nearer the front so you can rest your feet on them instead of the pedals.

Looking forward to see this realised. This is the exact kind of thing I was thinking of doing for a future project.

Kudos

 

[wallemannen]

thanks for your input!
The pedal position is acually a thing that I have spent some time to get right! and i have taken some messurements from my old streetbike to get the seat-pedal position where it feels good.
I'm a old motocross rider and really like an agressive ride style, moving my pedals forward away from under my body take away that agressiv feel. The bike is for city streets and maybe a gocart track or two :wink:
so no cruising intended!

 

[Miles]

Bottom bracket position makes sense to me. It actually looks better, too.....

 

[wallemannen]

Bottom bracket position makes sense to me. It actually looks better, too.....

Do you mean hight enough from the ground?

 

[Miles]

Yes, what is the bottom bracket height?

 

[wallemannen]

Yes, what is the bottom bracket height?

The lowest part of the frame is 140mm from ground and
the cc of pedalshaft is 220 from ground
The pedal is 110 mm from ground at its lowest point

 

[Miles]

Yes, what is the bottom bracket height?

The lowest part of the frame is 140mm from ground and
the cc of pedalshaft is 220 from ground
The pedal is 110 mm from ground at its lowest point

Quite short cranks, then. Seems ok.

 

[Miles]

The bike is for city streets and maybe a gocart track or two :wink:

You have lots of room for cargo, too.... 8)

 

[Miles]

Have I got this right?
What is the Q factor? ( http://www.sheldonbrown.com/gloss_q.html#qfactor )

 

[wallemannen]

The bike is for city streets and maybe a gocart track or two :wink:

You have lots of room for cargo, too.... 8)

what do you mean with Q-value?

 

[Miles]

what do you mean with Q-value?

 

[2moto]

I like the design. I suppose as long as you don't pedal through corners and keep the inside pedal up, you'll be OK with ground clearance. The offset on the fork yokes seems a bit large which means the front wheel trail is virtually non-existent. You might think about reducing the yoke offset to increase the trail measurement to somewhere around 40-50 mm minimum. It will make for a more stable ride.

What gauge (thickness) is your steel tubing?

 

[wallemannen]

Ah I saw your link now
the Q-faktor is 235 mm if i've understod the diagram right

 

[Lebowski]

thanks for the reply!
I see your point with the pedal position, but I don't really go for a cruiser style, I aim for a more racing style seating position. A sort of cafe racer style.

If you' re going for an old school board track style I would swap the handlebars for clip ons to go underneath the top crown plate

 

[wallemannen]

I like the design. I suppose as long as you don't pedal through corners and keep the inside pedal up, you'll be OK with ground clearance. The offset on the fork yokes seems a bit large which means the front wheel trail is virtually non-existent. You might think about reducing the yoke offset to increase the trail measurement to somewhere around 40-50 mm minimum. It will make for a more stable ride.

What gauge (thickness) is your steel tubing?

The fork I used for the model i actually from an old moped but i might make new yokes and just use the forklegs.

the thickness of the tubing is 22mm ID and 2 mm wall thickness

 

[Miles]

I like the design. I suppose as long as you don't pedal through corners and keep the inside pedal up, you'll be OK with ground clearance. The offset on the fork yokes seems a bit large which means the front wheel trail is virtually non-existent. You might think about reducing the yoke offset to increase the trail measurement to somewhere around 40-50 mm minimum. It will make for a more stable ride.

You can use this simple calculator to check your trail: http://yojimg.net/bike/web_tools/trailcalc.php

 

[2moto]

the thickness of the tubing is 22mm ID and 2 mm wall thickness

That will make for a relatively heavy frame, then. But certainly very strong. As you say, since you have plenty of it, you might as well use it. For comparison, we usually use 1.5 mm wall tube for competition motorcycles.

 

[Miles]

......... the Q-faktor is 235 mm if i've understod the diagram right

Just measured mine at 200mm. As 2moto said, it seems like you'll be ok if you don't pedal around tight corners

 

[wallemannen]

thanks for the reply!
I see your point with the pedal position, but I don't really go for a cruiser style, I aim for a more racing style seating position. A sort of cafe racer style.

If you' re going for an old school board track style I would swap the handlebars for clip ons to go underneath the top crown plate

I might do something like this for a more retro look

 

[2moto]

Oh, the other thing I meant to mention in terms of chassis dynamics is that I would try to place the battery mass at or above the wheel spindle height. Placing it below as shown in your scetch will not be ideal. I know that packaging is always a compromise between looks and function but this is an important one if rideability is important.

As a contract, if you've ever watched a program called American Chopper, they produce mainly bikes which are not meant to be ridden, and for good reason!

 

[1000w]

Just wanted to let you know that I love the look of your design and I hope to see this one come to fruition.