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Compulsive Bike Builder
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Discussion Starter · #1 · (Edited)
This is my electic assist conversion bike.

I suppose the first thing I need to mention when I talk about my electric bike to serious cyclists is HOW I use it. This bike is not a replacement for my road or mountain bike - it is a partial replacement for my car. I run errands with it. Most serious cyclists need to approach a bike like this differently than casual riders or non-cyclists. I could run errands without the electric assist. By using electric assist compared to pedal power only, I save 30 minutes ride time plus the extra time getting dressed and showering, since I don't work up a serious sweat or change clothes with the electric bike. With the electric assist bike, I still pedal the whole time, and I have *time* to run my errands while riding instead of driving. Actually in my case, due to a big hill in my route, the electric assist makes cycling the route possible - I just would not do it with pedal power only.

So, with all that said, here is my project:

The motor is in the front hub, the battery is on the rack, and various electronics are on the handlebar (but not the handlebar bag!) and the rack. This is a conversion of an existing bike I had, and the original drivetrain is still intact. I am always pedaling along with the motor. It is a two wheel drive! It is also a hybrid vehicle, but instead of gas/electric like a car it is a human/electric hybrid. If the battery dies, I can still pedal my way home, which I have had to do several times.

I really cannot speak to speeds and ranges like the companies publish for these kits. I am always carrying extra weight, and always climbing or descending some kind of grade. By judiciously using the motor, I estimate I get 8-10 miles per charge. Given the grade and loads involved, that is pretty good. I would say that electric bike technology has reached a level where it is useful to many people now, but I suspect few people are aware of it.

More pics:

The trailer is a Burley Flatbed. Kind of a poor man's BOB, but is also offers a bigger flatter floor. The tongue folds under and the wheels have QRs, so it collapses nicely. I have drilled a couple of extra holes for bungie attach points.


I intalled this "alternative hitch" that Burly offers. You cant see much of it in this picture unfortunately, but that is kind of the point. It is much smaller than the regular hitch - it replaces your skewer and the trailer has a big clip and backup strap. This also allows room for a rear kick stand, which I feel is necessary for an errand bike like this.


The battery is pretty unobtrusive, but heavy. The kit comes with a rack, but it is pretty cheap, so I installed my own rack. The frame does not have braze ons on the seat stays, so I use some rubber coated pipe straps. The kit (motor, battery, etc) weighs 35 lbs, more than the bike. So far, after about a month of regular use, everything is holding up well. I also installed DH saddle since I don't ride with a chamois and I could not bring myself to get one of those big cruiser saddles or gel saddles. It has worked well, too. Ti rails, no less.

This is a lead acid battery pack. Battery technology is improving for electric bikes, but more slowly than for bike lights, computers, etc. Nicad, NiMH, Li Ion, and even Li Polymer batteries are all in the works, and some are in the market, but they are just coming available. The NiMH batteries are a big array of D cells strapped together, believe it or not, because no one makes NiMH this big, yet. Even this is 3 12 volt lead acid batteries in series. The motor can accept more voltage for more power. There are also more powerful motors. This one is 600 watts. The possibilites of tuning and upgrading are endless.


My previous suspension fork - a Skareb - did not have enough clearance for the motor, and the motor manufacturer warns that most suspension forks cannot handle all that weight in the hub. So I went to a simple steel fork. The bolt on hub is not made for lawyers tabs, which my fork had, so I had to modify the washers to fit. The rim in this kit is very wide and single walled. A little cheezy, but once this thing pays for itself several times over I may look at a different rim or motor. Compare this to gas prices and it won't take long to pay for itself.

The motor adds drag when not in use - the front wheel does not freewheel for long when you spin it. Between the weight of the kit and the drag of the motor I was skeptical that the kit would do much good. But it does, you just have to learn to use it. My first tendency was to always ride at full throttle. Sure it's fun - there is a lot of power to be had. But it burns out the battery pretty quickly that way. I just apply the throttle to the point where I feel it pulling me a little and leave it at that level. Plus, I do not use the motor to help me accelerate way from a complete stop. This kind of motor has enough torque to do that, whereas some to not. However, accelerating from zero uses a ton of battery power, so another benefit of being a hybrid is that you can stretch battery life a lot with your own effort.

This motor does not have regenerative charging, i.e., braking does not charge the batteries. Units that do cost over twice as much. It is a one speed motor. There are two speed motors available, but that adds more cost and complexity, too.


This is the throttle, thumb actuated. I had rapidfire shifters, but the reach to the throttle was very long, and it was easy to confuse the two thumb paddles. I could have gotten used to it, but this is the better way to go.


Here it is at the fueling station. It takes about 4 hours or so. Excuse my digital retouching (here and in other pics).


Bungies can hold down any load I have tried thus far.

Yeah, you gotta be willing to look a little geeky to ride something like this, but I suppose that is in the eye of the beholder. I don't change into riding clothes for my errands, and I find the pant leg strap is necessary. In the summer, with shorts and a stylin' short sleeve shirt, the geek factor is reduced somewhat.


It is off road worthy, I have found a fire road short cut for my route that is similar to this. Two wheel drive is necessary with those skinny tires, loaded trailer, and steep grades, but it does work.
 

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old skool newbie
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the powers that be

Thats a great idea, especially for the non-sweat build-up factor

Since this is a MT-bike site some justification and explanation for its use and your bike choice is needed, but you had me at hello.

more power to you
 

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Hairy man
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Nice ride

How is your rear wheel holding up to the weight from the trailor? When I drag my daughter around in the trailor I have major trouble with my spokes de-tensioning. (the problem has snowballed do to irregular maintainence.) It looks like your carrying some heavy loads.
 

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Compulsive Bike Builder
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Discussion Starter · #6 ·
Good question - OK so far

Dwight Moody said:
How is your rear wheel holding up to the weight from the trailor?
So far so good, but I have only used it for a couple of months. I expect the front and rear will need more maintenance than usual. With my loads, I can keep the weight farther back, so less of it is carried by the bike, and more by the trailer.
 

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I like it! That's a great idea. I've seen a few of those on E-Bay before and wondered about them.

Get a computer on that thing and give us some mph's!

I can almost see myself doing that next year. If only I could wake up early enough to have the time to ride to work. ;)

Great write-up!
 

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Compulsive Bike Builder
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Discussion Starter · #8 ·
Its fast!

AndrewTO said:
I like it! That's a great idea. I've seen a few of those on E-Bay before and wondered about them.
Get a computer on that thing and give us some mph's!
I can almost see myself doing that next year. If only I could wake up early enough to have the time to ride to work. ;)
Great write-up!
I am thinking about selling them, and with something this unusual I wanted to try it for myself to make sure it was a good product. It has its quirks, but if you look at it as a first generation product, it is a great start. I predict these will advance in technology like bike lights or computers or hybrid cars.

I spent so much of my original post talking about the installation, I forgot to mention what it was like just to ride it as a hot rod and not as a beast of burden. It is suprisingly fast! I would say at full throttle in neutral conditions (no headwinds, grade, or pedaling) it is good for 23 mph. And I am a 195 lb rider, lighter riders will go faster. It is rated for a 20 mile range under those circumstances, but I don't think I could find a 10 mile strectch like that around here.
 

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DirtDad said:
I am thinking about selling them, and with something this unusual I wanted to try it for myself to make sure it was a good product. It has its quirks, but if you look at it as a first generation product, it is a great start. I predict these will advance in technology like bike lights or computers or hybrid cars.

I spent so much of my original post talking about the installation, I forgot to mention what it was like just to ride it as a hot rod and not as a beast of burden. It is suprisingly fast! I would say at full throttle in neutral conditions (no headwinds, grade, or pedaling) it is good for 23 mph. And I am a 195 lb rider, lighter riders will go faster. It is rated for a 20 mile range under those circumstances, but I don't think I could find a 10 mile strectch like that around here.
Holy crap! That's almost 40 kph! I could almost sleep in! :p :D
 

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Compulsive Bike Builder
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Discussion Starter · #11 ·
I plan on making that upgrade

Rufudufus said:
Nice write up. With regenerative charging, this would be great for commuting in hilly areas.
I am sure a regenerative kit will become more powerful and more affordable in the near future. There are a couple out there right now in the $1000 price range - they also featured nicer batteries, etc. But I chose this one for price, and because I wanted to consider selling it. Once this pays for itself, a nicer one will be on the way.
 

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Compulsive Bike Builder
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Discussion Starter · #13 · (Edited)
Those and others...

That is an interesting product, and I am glad to see products like it in the market place. They garner a lot of financial backing like Tidalforce and eBike - www.evglobal.com. That means a lot of people believe that electric or electric assist bikes have a big place in our future, and I agree.

All of those complete bikes are pretty expensive, but they make sense compared to the cost of operating a car, and the are accessible to the non-do-it-yourselfer.

The beauty of a conversion like mine is price and flexibility. The electric kit I installed, complete with upgraded (12 aH) batteries and the torquier 36V 600W motor, is around $400. The trailer is around $200. Of course, I had to add a bike to the price. But for the serious cyclist that is an advantage. Many of us already have one available to convert. Plus you can end up with a higher end bike that way - I have XT/XTR, Avid, Egg Beaters, etc., which is nicer than you can get on those complete bikes. Some electric bike company may offer that, but think of what the price would be. On the downside, I did have to change a couple of other components that add to the price, like the skinny tires, shifters, rack, etc. But once again, they were my custom choice, and they are nicer (or at least I like them better) than what the pre-packaged bikes offer.

I also like the simplicity of a direct hub drive. Tidalforce uses that design. Other designs require a belt or second chain if you want to be able to pedal and have the motor help. The weight, simplicity, and packaging advantages of a hub drive trump any flexibility advantages of other designs, so I think in the long run hub motors will win over. It would be nice if they were lighter and more compact, especially to allow room for disc brakes or suspension. But I think the wheels of technology have been set in motion, and all that will be coming sooner or later.
 

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ballbuster
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That's great

I apologize in advance. Here I was about ready to laugh myself silly... saying 'why use a motor when you can pedal up the hills?' Now you got me thinking about doing this myself as a way to avoid hauling small to medium bits of stuff in the car.

I have seen electric assists as more a lazy man's tool, but now I can seriously see it as an enabler to do real work on a bike, 'cause cars suck (compared to bikes), but they are nessisary suck. I'd like to make mine less nessisary.

I've even seen folks build powered trailers, like a booster. Some guy at Stanford built one himself.
 

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Compulsive Bike Builder
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Discussion Starter · #15 ·
That is how most cyclists react at first

pimpbot said:
I apologize in advance. Here I was about ready to laugh myself silly... saying 'why use a motor when you can pedal up the hills?' Now you got me thinking about doing this myself as a way to avoid hauling small to medium bits of stuff in the car.
Most cyclists react that way - like it is cheating. But seriously, when was the last time you ever thought about using your bike for a trip to the grocery store, hardware, Wal Mart, bank, etc.? If you did get a trailer for your regular bike, would you use it? Honestly? If so, then why aren't you? Do you have the time? It is not a matter of electric bike vs. regular bike, it is electric bike vs. car.
 

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i have a 5 year old giant lafree that i occasionally ride to work. i also like the reduced sweat from the electric assist. i can take it easy on the way to work, and arrive fairly fresh. on the way home, i don't have to worry about it.

the giant will probably get about 20 miles to a charge, and i think i am probably cruising about 15-18 mph on the flat. don't know for sure, since i don't have a computer on the thing.

just as the original poster, i have two long hills on the ride, so without the assist, i'd work up a good sweat on them. with the assist, i pedal as hard as the flat, and only have to kick it down a gear or two, so i don't lose much speed. i was knocking out a 5.7 mile commute in 22 minutes, roughly a 15 mph average.

my office moved this winter, and when i start back up in the spring, i'm curious to see how much time the additional mile and a half i'll have to travel adds. i have fewer lights, and only one moderate hill.

on the techinical side, the giant lafree is bought as a complete bike. i got mine off the floor of the lbs for $750 back in 2000. i haven't changed anything, although i probably only have about 150 to 200 miles on it. i need to change the seat and post, since there is no adjustment in the tilt or anything, just height. the new models may have improved that area.

it only has one chain, and the motor turns the crank, although i haven't taken it apart to verify, mainly because i haven't had to. taking off the front and rear wheels for flats isn't a problem.
 

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Compulsive Bike Builder
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Discussion Starter · #17 ·
Yeah, a couple of other options

Thanks for that. I forgot about the Lafree when I was generalizing about electric bike designs. It is a different approach yet, and Lafree owners seem to be happy with their bikes as a whole. I also think it is very cool that one of the big bike makers makes an electric. Does Trek, Specialized, Cannondale, etc. make an electric? I don't think so.

SRAM has and electric group. The signs are everywhere - more electric bikes are in our future. Maybe Shimano has an electric group or is working on one. What is next? A Cadillac electric bike? A Hummer H4 electric bike? A Ferrari electric bike? A Ducati? Who knows?
 

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Fast Eddy said:
It would be fun to make a four-wheel-drive off-roader out of four of those motors and 20" bmx wheels.
Trying to re-define all-wheel drive, are we? Just make sure it's independant suspension.

Damn, that could be expensive!
 

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As one that has done quite a bit of experimentation along these lines what I have come to the conclusion is that a unit like this is the best solution. I call something along these lines an ABUV (Auxillary Bicycle Utility Vehicle).



It seems like any of the options available that retrofit to the bike itself are cumbersome and preclude the use of the bike, as, well, a bike. By having the motor on a trailer you can easily adapt to any bicycle with the possibility of going to the trailhead and arriving fresh and ready to rip, then stopping by and doing some shopping on the way home. Or just using it to commute with or do some hauling, have fun going to the PO and leave the 4 wheeler at home type of action.

For those country bumpkins in need of a longer range a small 1.5 hp 4 cycle engine mounted to one of those attachments that you can get for a kid to pedal behind you gets 200 mpg and you can get a 30 lb. 5" travel bike to a trailhead 20 miles away at an average speed of 20mph, ditch the unit in the weeds and come back with groceries against a wicked headwind.

The one thing I have found on all my "experiments" is like DirtDad says, you tend to pedal about as much, but with less effort and in the BIG ring. I find that getting right up to the point of breaking a sweat and staying there gets the best results and is kind of like riding a tandem, with Lance Armstrong as a stoker.

Here are a few pics to share.











And a good base for the Feddymobile,



Every little bit helps :)
 
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