Safe's Electric Bike Project #003

[xyster]

You're building 003 when you haven't even ridden 002 yet to work out bugs, and see how it might be improved or altered

What can I say... I ran out of good weather.

Invest in winter wear. Like riding, testing does not require racing. You could race during the summer and test the rest of the year.

 

[safe]

This is the latest sketch of where I'm thinking project #003 will go. I'm starting with a rear swingarm that is shorter in height relative to the seatpost. (this way I can spare my 24" frame from being cut apart for the time being) I'm going to remove the seatpost completely and put in a piece of the 2" x 2" main tube. Hopefully this will make for a really low amount of frame flex when pedaling.

The seat shock is hidden by the right leg... the whole seat fairing is suspended... (front forks will have the threadless headset and rigid triple clamp forks)

 

[safe]

Keep It Simple Stupid

This is a simpler design. No seat suspension, just an adjustable standard bicycle seat tube. The seat fairing will need some mounting up near the headset, but I'll figure that out later.

This bike frame should be closer to about 8 lbs which is not bad...

 

[safe]

Latest Thinking

The battery would be a flat 5 across and 12 in length 3.5Ah SubC 10C cells that would be set up to produce 36 volts at 30 amps at only about 5C. The weight would be only 8 lbs. Since the design is a flat plate I could stack them behind the fairing if I wanted to increase the range. For now I just want to test the motor and range is of less importance. The price for the cells would only be $161.40 so even if they don't last that long I'm not going to be out a lot of money. The amazing thing is that for 8 lbs I would get 41% of the energy of my current massive 38Ah SLA cells.

The theoretical peak current would be 70 amps, I'd just use 30 amps.

The metal arrives tomorrow, so the welding will be started soon...

 

[safe]

The metal has arrived. Yeah!

 

[safe]

Headset Welded

First picture of the frame...

 

[safe]

Basic Frame Welded and Primed

This is the basic frame with primer. I know that later there will be the need for all kinds of little mounts for the motor and battery and seat, but I want to assemble this as a simple bike frame first and ride it around a little to make sure everything feels right.

It feels very lightweight... about the weight of a typical steel mountain bike frame (6-7 lbs maybe) and so I'm really going to be starting with a "normal" bike on this one. Nothing like the 20 lb frames designed to handle 60 lbs of batteries and 100 mph or anything like that on my first two projects. The second project hasn't even been finished, so it looks like this spring (if I manage to get all the work done) I'll have two separate bikes to be testing.

The frame is the same dimensions as the #002 project, so all the fairings will fit on both bikes. (I keep repeating that don't I?)

 

[safe]

I Now Present "Mini-Me"

While I might once have been satisfied with something as trivial as a "death laser" or "magma drilling screw" I've now turned my attention over to electric bicycles and am ready to introduce "Mini-Me" the smaller version of my other evil projects...

 

[safe]

Comments

As for actual feedback I've been able to do the bottom bracket flex test on the frame and it seems really stiff. To do the bottom bracket flex test you place the crank in the bottom position and from the side of the bike you press down on the pedal with your foot trying to get the bottom bracket to swing outward away from your foot. On a cheap bike you can get something like half an inch to an inch of flex doing this. This bike is rigid... so it's turning out well so far. Those forks have way too much steering offset and would make the bike very sluggish to steer. I'm planning to make some triple clamp forks like the choppers use. I thought about buying the chopper forks, but they have too much offset as well. The "Road Racer" concept is to have a long wheelbase and a pretty steep head angle coupled with little offset. That makes the tire react quickly and produce quick rotation to a lean, but it also means that the bike tracks through the turn slowly. So it's an inverted design geometry compared to the typical short wheelbase, shallow head angle, and large offset fork.

Eventually I'll get the bike setup to ride around a little and see how it feels... (might do that tomorrow and just suffer through with these forks)

 

[safe]

First Ride Feedback

The bike feels very good. It turns out the cranks are only 165 mm and actually it feels pretty nice having the shorter ones. The 175 mm give better torque, but you have to make such an effort to move your body to use them that the short cranks feel like a vacation from the usual effort. :lol:

As for stiffness/rigidity, it seems really firm... obviously things like frame twisting at high speeds won't be testable until I get up to some serious speed and at present I don't even have any brakes or gears on the bike. It's geared about how a BMX bike is geared, very low. Also, I'm using the thinner tires, so I don't think I'll be generating quite the high stresses that the fat 3" tires produce. These tires are a slim 2.35", but the tire compound seems pretty soft so they do a decent job.

The fork geometry is terrible because of it's excessive steering offset. (something like 1.75" - 2") I think the ideal offset will be more like 1.25". The result is a bike that doesn't feel comfortable in a lean and the steering fights you as you get into deeper. A shorter steering offset makes you want to get deeper into the turn and it's also more stable when at a severe lean angle. So the new forks that I'll be making will address that issue. The headset parts were ordered today and they won't get here for a few days. The local bike store wanted $30 for a standard threadless headset! Online I bought a headset for only $10.

The pedal clearance is really great. I'll be able to locate the motor and battery pack in front of the pedals and inside the front fairing. It's the ideal location for batteries (not hanging off the back! ) and with the long wheelbase there should be no problems with the legs running into the pack. You definitely don't feel cramped up with this frame, you feel like you can spread out and the long wheelbase allows you to put everything you have into it without fear of wobble. At slow speed it's sort of awkward to ride, so it's a trade off.

And would you look at that... a kickstand!

 

[Beagle123]

Truly excellent work, safe.

 

[dirty_d]

hows it feel to pedal with your legs behind you instead of in front?

 

[safe]

hows it feel to pedal with your legs behind you instead of in front?

The reason that I did that with the seat tube is that the fiberglass fairings that I plan to use have a shape where the shock absorber normally goes right about there. So by pulling the seat tube back I don't have to make any changes to the fairing. In reality the "real" (future) seat fairing is very long and you can slide forward and backwards a great deal in order to shift your weight back and forth. Where the seat is now would be the furthest forward position on the seat fairing.

All that said...

Since the bike is so loooooong you are naturally in a more "Road Race" position to start with and so you have more weight on your arms than a typical bike. Having the bottom bracket backwards means the you can sit and pedal more easily than if the bottom bracket were more forward because you don't have to lift your legs as much. However, in the "real world" of using this bike in the "Sit and Stand" riding style similiar to a BMX bike the seat doesn't matter that much. The only time you use the seat is when you are not pedaling or not serious about pedaling. The bike is designed for a one hour sprint "at most". Endurance riders that want to drone on and on with some long trek would be better off with a more conventional setup.

My bikes are designed strictly for "Sport Riding" and this geometry seems ideal for it.

Dirty D... your motor is located in the rear and that limited your ability to place the bottom bracket backwards... had you front mounted the motor you could have done this too. It's really an open feeling to be on a long bike... and REALLY USE IT... lot's of leg room.

If you look at a typical bike the seat is at about a 70 degree angle to the bottom bracket. When you adjust for the actual seat fairing that I'm planning to use it should be very close to that. Dirty D, you have unknowingly produced a "Chopper Bike" with forward mounted pedals.

Looking at the "Chopper Bike" it's pretty obvious that you can never stand up and pedal on it. (no leg room and no leverage) Notice on the track bike how low the bars are and how this stretches your upper torso forward and flat. This position is very powerful and aerodynamic. The stem reaches forwards to try to lengthen the bike... longer bikes give better leverage if you can get the bottom bracket further back.

But this issue is really the "tip of the iceburg" of "sport verses casual" riding design. Generally speaking if you are sport oriented you are going to want to have your bottom bracket back and your body stretched out forward for better leverage. For casual riding you would want to have a comfortably padded seat, your legs forward and pulled back handlebars more like a chopper.

My bikes obviously take after the track bike design style...

 

[D-Man]

What's your plan when your back starts to hurt and can no longer ride these types of bike? Shouldn't be too much longer since your in your 50's.

 

[safe]

What's your plan when your back starts to hurt and can no longer ride these types of bike? Shouldn't be too much longer since your in your 50's.

Nearing 50... 46 at the moment.

Well, the great thing about electric power is that you can choose to sit and let the motor do all the work. When in the sit down position it's comfortable enough for a one hour ride. The stand up is for short bursts of speed or hill climbing. (and to comply with the Federal Law that requires operable pedals) Just think of a BMX bike... you pedal standing up. In the sit down position on flat land the lowered aerodynamics cancels out all the pedal power you could possibly create anyway... so why even bother pedaling on the flat? That's the central idea.

The bike isn't just for me... the idea is to create a new product category of the "Electric Road Racer". My expectation is that most of the people that might buy it would be younger and probably attracted to motorcycle road racer bikes. For a low price you could get a lot of the fun of a full sized road racer and save the environment at the same time.

What could be better for the world?

It's far more comfortable than it might seem...

When I get so old that I can't ride anymore then I'll start work on "Road Racer Wheelchairs". (which actually looks kind of cool) Or trikes, or nothing... who knows?

 

[fechter]

How about putting dual motors one one of these:

 

[TylerDurden]

If two are good...

 

[Mark_A_W]

What's your plan when your back starts to hurt and can no longer ride these types of bike? Shouldn't be too much longer since your in your 50's.

Looking at that geometry I don't think it's your back that's gunna hurt..


NUTCRACKER!!


Safe, can you actually sit on it without doing yourself an injury

 

[safe]

Safe, can you actually sit on it without doing yourself an injury

I'm not a big fan of those little seats and with the seat fairing I'll be making the seat will be covered with 1" foam to make it really cushy. The position feels good... more "Road Race" than "Chopper", so if you are comfortable with road racer motorcycles then it feels normal.

This is one of those cases where if you actually tried it you would go:

"Wow... I'm surprised... that feels better than I figured it would..."

Is this guy comfortable or not? Probably less comfortable than a chopper, but he's having fun doing what he's doing anyway. (comfort is only one goal to pursue, the other is speed and performance)

 

[Drunkskunk]

They are obviously find the bikes very uncomfortable. Look at them! They aren't even sitting on the seat!

 

[D-Man]

Actually, they're farting. Their trying to attain Doc Bass's theory.

 

[safe]

Which is more fun?

...or this?

The choice is yours... :wink:

 

[Drunkskunk]

Well since the motorbike riders are either having hemroid trouble, or bad gas, I'd say its the kid. I mean really. Just look at that kid's face! he's obviously in a state of pure joy, Like he just discovered girls, or he just ate 16 pixie stix and a bottle of Jolt, or he's riding the bike with no seat on the post. Whatever works for him, he's obvoiusly realy happy.

 

[safe]

If you ride a motorcycle road racer (and know anything about handling) and then switch and ride something like a Harley the natural question becomes:

"Why does anyone ever buy a Harley?"

...and the answer is in part that many people are just attracted to Chopper/Harley fashion. The other reason people buy the Harley over the road racer is that the Harley has a motor that has a certain sound and vibration that people find exciting. Ride with a girl on the back of the Harley and... well... it's a a type of vibration the women love. :wink:

Only the people that really get into the bike and the technology tend to gravitate naturally away from the image conscious Harley crowd and into the road racer bikes. You have to actually know something about bikes and bike handling to appreciate the high tech bikes. It takes a "refined taste" to like MotoGP bikes... the mainstream uneducated (in motorcycles) crowd just goes by fashion and buys the Harley. (they often know nothing about the technology and don't know that up until recent the Harley hadn't changed for decades)

But we have a lot of people here in the electric bike area that are "Super Dorks" that would neither go down the Harley route nor the Road Racer route and want the electric bike to represent them in their native dorky state. (Xyster represents this to a degree, but his "Hemi" hub motor is his secret act of rebellion 8) ) So I feel like I'm trying to get the dorks off their modifed regular bikes and move them into a new concept. Or better still... skip the dorks entirely and attract new people to a new "Electric Road Racer" concept. To do that I need to "do my homework" and produce something that appeals to the technically sophisticated crowd that knows a lot about bike handling.

Up to this point the electric bike has a dorky reputation... I want to change that... it's like the electric bikes are wearing pocket protectors! :lol:

 

[safe]

What Pedaling Will Look Like

This is roughly what an Electric Road Racer would look like when he was standing up on the pedals and pedaling.... you would do this when:

You were climbing a hill.

You were going less than 20 mph.