wider front fork for rear-style hub motor?!

[mr.pibb]

OK I am brand new to the forum. I just really started looking into electric bikes only within the last week.
I love what some of you guys have come up with and I had to join the forums.

I have owned a curry trailz for about 2 years and love it.
Before recently watching youtube videos inspiring me to join and build a new bike, I started small with some ideas of my own on the trailz.

1. I added a HUGE honda goldwing trunk to the back for storage. As a bonus I got intergrated taillights in the trunk with a built-in back rest as well.
2. I have ugraded the batteries (twice now) to larger sealed lead acid mounted on the sides where the old battery went.
Currently I am running 24v with a capacity of 35 ah. This give me an insane range of 50 miles, but realitively slow 17 mph compared to other bikes.
3. I am adding a 40 watt solar panel above the trunk sort of like a spoiler if you will. (ordering now)

I will post pics soon.
The bike is fun and perfect for a beach cruiser. I can put towels in the trunk and whatever else I need and have a fun day.
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However now I am onto a new project. I want to make a "commuter" bike capable of near 50+ mph!!

I have a donor bike that is a a2b ultra motor velociti 26.
Nice bike but no battery so I want to do a complete overhaul.

Here are my plans:
crystalyte hs-3548 rear hub motor
crystalyte controller
crystalyte apm led readout
96v total SLA batteries (8)*12ah

Heres where my issues come into play. I originally was just going to upgrade to the hs3540 and be done. But I was thinking:

I could put the stock a2b 500 watt rear motor to the front of the bicycle and instead get a hs3548 for the rear. I would be losing the off the start torque with the 3548 motor vs the 3540. However with the "boost" of 500 watts from the front motor I would estimate the take off to be about equal to the 3540. And I would get a higher top speed with the 3548 motor!

(I would only really use the front motor for torque boost for off the line starts. I image at speeds higher than 20 mph it would not help any because thats the top rpm of the motor)

Do you think my "idea" sounds about right?

Now the issue is the rear hub doesnt fit in the front forks.(thanks murphy! :| ) I would have to get wider forks. Standard width is 100mm.
I have found I can get 135mm wide forks realitively easy. I am not sure if that is even big enough. I need to get the free wheel off first to measure it, but it looks really close. Has anyone done anything similar? I found this fork on ebay: http://www.ebay.com/itm/SURLY-PUGSLEY-907-FATBIKE-OFFSET-135-MM-FORK-LARGE-MARGE-SNOW-BIKE-/251151310124?pt=LH_DefaultDomain_0&hash=item3a79c8dd2c Do you think it would work?

Do you think it would be worth it to use the old 500 watt hub motor or to ditch it all-together? I really dont have another use for it so I figured it would be worth reusing?

Thank you for taking the time to ready my long post. Just had a lot to say right off the bat. Thank you also in advance for any help or advise !!!

PS: I know SLA is not the way to go but I dont have the funds for lithium and I understand that lithium is better. I will try to upgrade that later in the future.

 

[biohazardman]

Front motor standard is 100mm rear 135 cuz that is what most bikes are. Yes, you can do anything if you want to bad enough, or have the need, so it's up to you to decide if it is worth it monetarily and time and effort wise. Will it werq? With mismatched DD motors it will probly be difficult to power them up evenly and complicated to wire up two controllers and program them to share the load well. So efficiency will suffer. If one was a gear motor and would freewheel it would be easier. DD motors don't freewheel well so present a good amount of drag, you can really feel it when you hit the 10-12mph range while pedaling without the motor. So, when they are both not actively powered up the one doing the werq would have to overcome the drag of the slacking motor not a good thing. Get a good strong single motor and use the other for a windmill generator setup to charge your batts up. ;^)

 

[amberwolf]

However now I am onto a new project. I want to make a "commuter" bike capable of near 50+ mph!!

First, go find all the other threads where people want to make a 50MPH or other high speed bike, so you know the costs you are going to run into, and the stuff you're going to need, and the safety probelms you're going to run into.


There are a bunch of recent threads for such bikes.

There *are* several builds that have easily surpassed the speed you want, and there are some like John in CR's commuters that do those speeds, but they are either expensive or highly custom or both.

Just so you know what you are getting into.


(I wont' go into the legal stuff and consequences; you can research taht too if you care about it).

 

[mr.pibb]

Thank you biohazard for the info. It was just an idea and I am not set on doing it for sure. I understand it isnt an ideal system.
Im just working with what I have to make what I can. You know "lemons to lemonade"

If I did decide to use the old rear hub motor for the front fork I would just reuse the old oem controller as well and run it on a seperate battery bank at 36v(SLA). I dont think there would be any extra investment other than the new fork($88) well and the batteries . I would have 2 independent systems, so I wouldnt have any weird wiring or controller issues. I realize the controllers wouldnt match power but they really couldnt because they are completely different motors anyway. There would be 2 throttles. I was thinking I would use both throttles on my starts and switch back to only the crystalyte once I hit about 20mph. The old a2b(500w) would not add any power after 20mph. But going on what you said, if I did, it would lessen the drag on it. Which brings me to another point:

How much extra drag could the old a2b really add? I spin it and it spins freely just doesnt make very many revolutions. I understand that a crystalyte would have considerable more drag, but this doesnt seem terrible. I guess I really just dont have much experience with DD motors. I have the a2b but honestly have never really ridden it because I never had a battery.

I am not set on having a dual drive bicycle. I just thought that I could get more top speed and the same torque with the 3548 and a2b motors vs the 3540 alone. In your opinion do you think that the extra drag on the additional motor will offset the addtional power anyway and leave me at the same top speed as the 3540? If I dont gain anything I will just go with the 3540 and be done.

I like the windmill idea too! Thats has got me thinking and Im looking into it. How much aprox. avg. sustained wind would I potentially need to make 500 watts from the old a2b motor?

 

[mr.pibb]

Thanks for the reply amberwolf.
I do not need to go 50mph and may not be able to hit it with the materials Im using. But I would like to get as close to that as I can. I will probably stay in the 25-35 mile range normally. However I would like to have the option of opening the thottle and flying every once in a while. I understand the costs invovled, (my budget is about $1000).

Here are my plans:
crystalyte hs-3548 or hs-3540 rear hub motor ---$400
crystalyte controller----------------------------------$160
crystalyte apm led readout---------------------------$90
96v total SLA batteries (8)*12ah -------------------$200
donor bike with 500 watt motor--------------------FREE
________________________________Total 850+ misc.

Im not trying to reinvent the wheel or do a insane build. I just want to have some fun, save some money, and be friendly to the environment.

I also know that fed. law dictates 750 watts & 20 mph unassisted. However Im not too worried about it and will deal with that when it comes to it. Ideally, I would like to make a bike that I can actually get titled and drive it on the road. I own a honda shadow so its not like I cant ride that. I just also like the idea of electric.

 

[amberwolf]

TI also know that fed. law dictates 750 watts & 20 mph unassisted.

Fed CPSC law has nothing to do with anything except production ebikes being sold.

 

[mr.pibb]

Interesting very interesting muhaha
8)
Im sure there is local laws that dictate the same or similar guidelines. Im sure I would legally have to title the vechicle which would probably be impossible anyway. So I will just ride cool, calm, and safely in the bike lane and try not to piss anyone off if possible.

Thanks again for the advise!

 

[dogman dan]

Have fun, and don't forget to pedal like hell when a cop is looking. It's your local state vehicle statutes that apply. Some have same as the fed law, others vary widely. The only way you'll build one you can register is to find an old frame with a vin number that was a street bike. Like a honda 125 or something like that.

I wouldn't sink a ton of money into lead batteries though. Once you start building a fast bike, you need to learn to handle high discharge rate lithium. You can easily build for 40 mph, but then actually ride it closer to 30 most of the time, and at 30 it's possible to go by cops without getting too much notice if you keep clown pedaling.

 

[dogman dan]

Mabye I need to clarify about the lead. Too much heavy lead is going to make the bike dangerous to ride really fast. What's fine for 30 mph fails at 40 on up. So it gets very important to lighten up the battery if a bike frame is going to ride safely at 40 mph.

 

[hjns]

Thanks for the reply amberwolf.
I do not need to go 50mph and may not be able to hit it with the materials Im using. But I would like to get as close to that as I can. I will probably stay in the 25-35 mile range normally. However I would like to have the option of opening the thottle and flying every once in a while. I understand the costs invovled, (my budget is about $1000).

Here are my plans:
crystalyte hs-3548 or hs-3540 rear hub motor ---$400
crystalyte controller----------------------------------$160
crystalyte apm led readout---------------------------$90
96v total SLA batteries (8)*12ah -------------------$200
donor bike with 500 watt motor--------------------FREE
________________________________Total 850+ misc.

Im not trying to reinvent the wheel or do a insane build. I just want to have some fun, save some money, and be friendly to the environment.

I also know that fed. law dictates 750 watts & 20 mph unassisted. However Im not too worried about it and will deal with that when it comes to it. Ideally, I would like to make a bike that I can actually get titled and drive it on the road. I own a honda shadow so its not like I cant ride that. I just also like the idea of electric.

I would say that the controller and motor are the easy part to get a fast bike. The more difficult things are:
- how to safely fixate the motor axis to the frame
- how to adjust the frame so that it can hold together when going +40mph
- how to deal with the very sensitive throttle when working with 2kW power or more
- how to deal with the high current (think 30A or more) that the battery needs to deliver in order to accelerate from 30mph to 40mph at all
- how to deal with the high voltage in a safe way, and how to charge the battery again with multiple cells in series.

If you think in terms of an electric Honda Shadow, then no, your proposed build will be nowhere near that in terms of handling at 40mph, dealing with bumps in the road, or range. On your bike at 40mph, your hands will be sweaty for holding the handle bars at that speed, while trying to keep the bike balanced, and trying to watch for any irregularities on the road that have a huge impact on the small tires of your bike.

Anyway, have fun learning stuff and build your bike! I know I did!

 

[biohazardman]

Thank you biohazard for the info. It was just an idea and I am not set on doing it for sure. I understand it isnt an ideal system.
Im just working with what I have to make what I can. You know "lemons to lemonade"

If I did decide to use the old rear hub motor for the front fork I would just reuse the old oem controller as well and run it on a seperate battery bank at 36v(SLA). I dont think there would be any extra investment other than the new fork($88) well and the batteries . I would have 2 independent systems, so I wouldnt have any weird wiring or controller issues. I realize the controllers wouldnt match power but they really couldnt because they are completely different motors anyway. There would be 2 throttles. I was thinking I would use both throttles on my starts and switch back to only the crystalyte once I hit about 20mph. The old a2b(500w) would not add any power after 20mph. But going on what you said, if I did, it would lessen the drag on it. Which brings me to another point:

How much extra drag could the old a2b really add? I spin it and it spins freely just doesnt make very many revolutions. I understand that a crystalyte would have considerable more drag, but this doesnt seem terrible. I guess I really just dont have much experience with DD motors. I have the a2b but honestly have never really ridden it because I never had a battery.

I am not set on having a dual drive bicycle. I just thought that I could get more top speed and the same torque with the 3548 and a2b motors vs the 3540 alone. In your opinion do you think that the extra drag on the additional motor will offset the addtional power anyway and leave me at the same top speed as the 3540? If I dont gain anything I will just go with the 3540 and be done.

I like the windmill idea too! Thats has got me thinking and Im looking into it. How much aprox. avg. sustained wind would I potentially need to make 500 watts from the old a2b motor?

Hard to say on the amount of wind. You can Google the windmill thing to find some good vane shapes and stuff. Expect there are sites out there that can give you a rough idea according to the type of prop you use how much wind you will need.

Sorry I can't tell you how much drag from the front motor. I do have and older 500W Goldenmotor DD and the drag is considerable though. Enough that I do not to pedal above the 12 or 14 mile range at all and usually stay near 10MPH. Your motor may have a different sweet spot in the speed and amount of drag area but it will be noticeable at 10-12MPH and strong at 20mph. Still you can always crack the throttle on the front motor just a bit to stop the drag. That would help allot with the efficiency thing as well. Something you could learn as you go. Good luck with your project and keep us in the loop.