Request Help and Ideas for Improving my eBike

[govman6159]

Here is an image of my latest revision to my ebike. For those who don't already know, it is a vintage Bianchi Main Street hybrid bike with a 24vdc/500 watt Currie motor/controller and a 24V/30ah LiFePO4 battery pack (16 Headway 40152S cells). I made the ebike this way (vice hub moter) because I wanted to still be able to shift gears. I've been riding it for about 3 months. Here are the pros (that I want to keep) and the cons (that I would like your help fixing)

Pros:
1) All gears are available which allows me to shift to whatever gear is required for the situation.
2) Great for commuting due to the hybrid tires (no flat tire or uneven terrain worries)

Cons:
1) Looks homemade (aka frankenbike)
2) despite the availability of all gears, it frequently shuts of when going up long slow hills (common around here (KY)) due to torque rqmts placed on the motor
3) On a flat road, 22 mph appears to be the max speed due to wind resistance. I would definitely like at least 35mph.
4) Exposed batteries invite theft

What I would like to do is keep the pros and eliminate the cons. My thoughts on this are:
1) Create a fairing of coroplast similiar to a crotch rocket motorcycle (enclosing or routing air past the legs)
2) Mount a handlebar extension to improve the aerodynamics of the riding position (this creates a problem for where to mount the throttle)
3) Switch to a mountain bike gearing (22/32/42t up front and 13-36t cassette in back, current setup is 28/38/48t front and 11-30t rear)
4) Upgrade to 48V/1200W motor (the ones I see look cheap and appear to be too wide to clear the pedal. This would require a high/forward motor mounting and limit the room to mount my batteries/controller).

What do you guys think. Any and all ideas/suggestions are welcome.

[Gealii]

you seem to be on track for adding top speed to your ev

as far as handlebar extenders do you mean the drop bar ones found on road/touring bikes?

Fairings would help enclosing everything with coro, also adding a boat tail http://ecomodder.com/forum/showthrea...-12455-16.html

[govman6159]

Handlebars similiar to this.

[bikin' Ed]

I got a clear plastic (lexan or whatever) from zzipper fairings. It makes a big difference in my speed or exertion level.

Going to chainrings up front with less teeth will not get you more speed.

Buy or build a rear package rack for your batteries--This will also give you something to mount a boat tail to.

[govman6159]

Originally Posted by bikin' Ed

I got a clear plastic (lexan or whatever) from zzipper fairings. It makes a big difference in my speed or exertion level.

Going to chainrings up front with less teeth will not get you more speed.

Buy or build a rear package rack for your batteries--This will also give you something to mount a boat tail to.

I checked out zzipper and that could be a good starting point for my fairing(s). Thanks for the info. I will def look into that.

I realize that chainrings w/ less teeth up front won't net me more speed. My reasoning behind that mod idea is to stop the motor controller from shutting off due to overtorque requirements placed on it when going up hills. Right now when I go up a hill, the motor frequently shuts off (usually at the worst possible time). I'm thinking it just can't keep up with the required torque. I noticed it happens less when I'm in the lowest gear (28t sprocket front and 30t sprocket rear). I'm imagining if I go with a 22t front and 34 rear when climbing a hill, there will be less torque rqmts placed on the motor and it will not shut off. Is that a valid assumption?

I know that my top speed is being limited by wind resistance b/c when I get to around 22mph on a flat surface and try to shift to a higher gear for more speed, I actually lose speed. I'm thinking the only way to increase top speed is to either get a bigger motor (w/ more torque) or, reduce wind resistance. What say you?

I originally had the batteries mounted on the back (see attachment) but it made it so unbalanced that it fell over easily when on the kickstand. It also caused a spoke to break (when I hit a bump) due to so much pressure/ weight on the rear wheel. It basically rode like crap.

[BarelyAWake]

I've had a number of gasbikes as well as the 48v 1000w hub drive ebike I currently use as a daily driver/commuter & generally speaking to achieve the "at least 35mph" (sustained) on a motorized bicycle requires about 2-2.5hp. Electrics do have a torque advantage but as even 1000w is only 1.34hp and wind resistance is exponential, even the 1000w hub manages only 26mph sustained, so your 500w @ 22mph is actually doing really well.

Reducing the wind resistance will ofc help, but such provides only fractional improvements, a mph or so here & there - a good example is the difference between riding upright and in an areotuck, which while a major difference in frontal area the gain at max on my ebike is about 1.5mph, about the same as the difference between smooth street slicks and knobby tires.

So while everything does add up, aeromods w/the ebike application & at these speeds provide more of a gain in a range return than a significant maximum speed - achieving the sustained speed you desire is going to require a fairly substantial increase in power, necessitating a motor upgrade & taking a very serious toll on your range...

Is it worth it? That's up to the rider ofc lol - it all depends on what your priorities are (& budget), but given your stated concerns I would suggest that 25-30mph is a more realistic expectation even with the "48V/1200W motor" upgrade you're considering (which is 1.6hp) but the hills would no longer be an issue.

I agree that the common rack mounted battery packs make for an unbalanced bike due to the high center of gravity - have you considered mounting your batteries in panniers? Wheel load is a concern, but you shouldn't be breaking spokes w/only an extra 16-30lbs... that sounds like another issue such as rim flex (single wall) and/or maladjusted spoke tension. I upgrade to lightweight but very strong & stiff double walled alloy rims for this "high speed" use with the added weight, they can be had quite inexpensively if the "big" brand names are ignored - try 'Alex Rims' for a reputable, but inexpensive alternative.

As you're in Kentucky this one may not be as simple as it could be, but for areomods & concealing/protecting your batteries - the heavy gauge shrink wrap used for off season boat storage has lots of potential. It's extremely easy to use, durable and very inexpensive as you'll only need the cut-offs, some scraps left over from a single boat wrap... which us the difficult part as you've probably not a lot of marinas where you're at lol

Still, it's a thought

edit: forgot, the 'Acclaim Double Black Kickstand' (amazon) is a very simple & sturdy aluminum center stand - I'd very strongly recommend replacing the treacherous side/kickstand on any motorized bicycle due to the weight

[govman6159]

Hey BarelyAwake,
Thanks for the detailed response and all the suggestions. I knew that wind resistance was exponential w/ speed but, I didn't realize it took so much hp to get to 35mph. Wooooowwww . 2-2.5 hp is a serious challenge for a small dc motor (and a serious current draw). I do feel pretty good about getting 22mph out of the small 500 watter (even though it takes a while to get there).

I'm trying to imagine how to use the shrinkwrap? Do you mean just wrap it around the whole triangle (minus the motor and chain area) and shrink it? Or... wrap it around each individual battery pack (leaving holes for venting of course).

My plan is to take small steps (one change at a time), evaluate the results and go from there. My first step is to change my rear freewheel cassette to a 13-34 tooth setup (ordered it last night) and see what that nets me. I'm expecting it to allow me to traverse most hills w/out any overtorque conditions from my motor. If that's not enough, I plan to change the front sprockets out to 22/32/42t or I may go w/ 26/36/46. I'll make that decision after I see how much more low end torque I get out of the rear freewheel update.

I was looking at the fairings from zzipper and I had some questions for you experts. The fairings remind me of a windblock fairing on an older motorcycle. I know they have some "roundness" to them but they don't look like they "cut" the wind very well. Wouldn't it be more advantageous to make a fairing similiar to this (attachment) but without the big opening for the radiator? It seems to me that a more pointed front (enclosing most of the front wheel) would be more beneficial??? Then add a boattail on the back and viola!!!! there you have it. And...is there anyway to calculate what the expected gains would be b4 I go through all this trouble to build the fairing? If it simply nets me range gains or a paltry 1.5mph gain, I don't really need that (right now anyway).

Window 12,
Lol. Personally, I like the look too. Its kind of growing on me but, when I go to the gym (I store the bike in their storeroom) and a new employee is there, they think I have a bomb on my bike and I have to explain it to them. I also work in a federal building and they are highly suspicious of anything that looks like this. I couldn't imagine what airport security would say if I brought it to an airport.

[bikin' Ed]

I was looking at the fairings from zzipper and I had some questions for you experts. The fairings remind me of a windblock fairing on an older motorcycle. I know they have some "roundness" to them but they don't look like they "cut" the wind very well. Wouldn't it be more advantageous to make a fairing similiar to this (attachment) but without the big opening for the radiator? It seems to me that a more pointed front (enclosing most of the front wheel) would be more beneficial??? Then add a boattail on the back and viola!!!!

I'm no expert but I'm pretty sure that a rounded blunt front end is all we need for the speed we achieve. The pointy "tip" comes more into play up around 700 mph or so. I don't don't have any quantative numbers, but I can tell you that the fairing makes me faster on the beater bike than un faired on a race bike.

[Ryland]

On my E-bike I mounted the batteries on either side of the rear wheel and it worked out great! it also meant that I had a rear rack that I could use to haul cargo, as for your rear spoke breaking... the extra 20 pounds on the rear was most likely not the cause, a flawed, cheap, rusted or loose spoke was most likely the cause, loose spokes are the most common reason for breakage.

I have a rear hub motor with a 7 speed free wheel on it and I've never had an issue with shifting gears, I've also never had an issue with it cutting out going up hills, but that would be because the speed controller is undersized and has a thermal shut down that is kicking in, so a higher power speed controller might be something to think about, even if you don't upgrade the motor a higher voltage speed controller will help you cut the losses in the wires as long as you don't over speed the motor, your speed controller limits the voltage to the motor at part throttle, so you could have a 96V battery pack and speed controller and as long as you didn't give it full throttle the motor would never see that full voltage, but the number of amps in the wires between the battery pack and speed controller would be much lower and at 22mph your motor would still only be seeing 24v or whatever voltage it requires to go 22mph, of course that would be a bit of over kill, but going with a speed controller that can handle higher amps and maybe a step up in voltage could be your best investment.

[Patrick]

1) I like the idea of the triathlon bars to get you into a tuck and reduce wind resistance. Maybe a 2nd throttle could be hooked up to allow you to use the triathlon bars?

2) Can you add a heatsink to the motor so it doesn't cut out so soon on the hills?

3) Can you increase the pressure in your tires or change to higher pressure tires to reduce rolling resistance?

4) How about moving the batteries to a flat plane inside the diamond of the frame to reduce frontal area and wind resistance? Try to make it only one battery thick so the pack is riding in the wake of the downtube. This would also lower the CG and help improve handling.