considering my first build

I was pretty close to giving up on the idea of an ebike until I found this forum, so thank you for all the incredible information; I'm still digging through it and will be for some time.

I've been commuting mostly by bicycle for the last 10 years. I say mostly because, living in a hot and humid climate, there are a few months of the year where I haven't been able to ride to work without smelling/looking like something that should be on 4 legs rather than 2 (let alone 2 wheels). I've tried the various bathroom wipedown rituals without much success, and showers at work aren't going to happen. So, in order to extend my biking season to the full year, use less gas, and put less wear on my old car (really don't want to buy a new car, ever), I'd like to build an ebike.

My commute is pretty short (1.5-3 mi depending on route. mostly the 1.5) and couldn't really be any flatter. Parking is quite secure, so not much to worry about there (secured facility requiring company badge to enter, plenty of bike racks). I'm not looking to build a 50mph electro-rocket or go on extended tours. All I really want is something that can propel me at regular bike speeds with minimal pedal effort so that I don't sweat too much, an electric assisted bike if you will.

I'd like to keep this on the lower end of the cost spectrum since I'm not 100% sure that an ebike is the right thing for me. Reliability and convenience are important as well since poor reilability increases the expense and inconvenience decreases the frequency of use. With this in mind, I have been considering a low-medium power, rear-mounted, brushless direct drive system with some sort of lithium battery. The brushless direct drive motor should be very reliable and low-medium power should keep prices down. The rear mounted motor will be better concealed with a rack and panniers, granted, as I read the law here in Texas, it looks like if it weighs less thatn 100lbs and can't surpass 20mph on its own it is not considered a motor vehicleanyways (don't want to test that if I can avoid it). I have an old GT Karakoram steel mtb frame on its way which should be a solid platform and provide a good place for the battery in the triangle. I've found some members on some of the bike forums that make custom bike bags, so getting a good triangle bag for the battery and whatever is needed to house the controller shouldn't be an issue.

My main concern is the battery. From what I have read it is the most troublesome and most expensive part of an ebike. Ideally I want to be able to ride the bike to work, let it sit all day, and ride it back home without having to charge it; I also want it to last as long as it can. I could charge at work, but my volitile schedule means that I'm not always at my desk to monitor the charge. Also, I don't want people to get concerned with the massive battery pack plugged into the wall, which the facilities folks my not be happy with if they found out.

The maintenance of an SLA setup won't cut it, which brings me to lithium. I am willing to sacrice speed/range for something that will last longer and not need to be immediately charged. I hesitate with this build because this is where things seem to rapidly become expensive if not thorough researched (which is why I am here).

Looking at other build threads, http://endless-sphere.com/forums/viewtopic.php?f=3&t=33819 is similar, but a bit more, than the final product I'm aiming for. Looks like a great commuting machine and the Marin has been on my shortlist of replacements for my current commuter if the need arose.

So to summerize:

GT Karakoram steel frame w/26" wheels
rear mounted, brushless direct drive (I think)
moderately powered to travel assisted at normal bike speeds
some type of Lithium battery - again moderate power
reliable - want major components to last several seasons
robust - want a battery pack that can go a few miles and sit for the workday before needing a charge and without sacrifing a lot of life
moderately priced - not looking for an extreme machine, just a little boost that I can hopefully get for $7-800ish (not including the normal bike parts)

Any advice is appreciated on everything from battery type, motor type, different brands (that's a big one actually), the bike platform itself...really any guidance will be appreciated. Thanks!

From what you say about your need, you'd be fine with Cell-man's Puma geared kit. You range is short and with your flat terrain, any battery will do. DD hubs can be fed more power, yet you don't need it. A geared hub is lighter and freewheels, has plenty of torque with little power required.

bc_dc said:

I was pretty close to giving up on the idea of an ebike until I found this forum.....

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Hey There!

I have never bought anything from cell-man, but he has been nice enough to email me back when I have asked questions of him. I could see my self doing business with him in the future.

I made my first build about 6 weeks ago. I bought a Yescomusa 36v 800w front hub motor for $250.
You can find them on ebay. It is kind of big and a bit heavy. Probably a golden motor hub. The controller is unknown but it works. The motor cuts when the brakes are applied as it should.
It moves me faster then the fastest road bike rider around here, on the flats and on the hills. I weigh 205 lbs.

I use 3 12v 12ah SLA's because they were cheap. $115 for the three of them. My 1st bike, a trek 800, ran great with the exception of not having any suspension. So I recently changed over to a road bike with front suspension and had to modify the forks. I am now going to have to add two torque bars in case the front fork cracks open. All the more reason to have a rear wheel kit.

To keep it short:
I would go with a rear wheel motor like you said.

SLA's take less maintenance then other batteries, (no balancing needed) but they are heavy (25 lbs all 3 combined) and won't last 4 years. And, you need to plug them in as soon as possible when you get home because they don't like being left uncharged. I can easily go 6 miles on my pack with little or no peddling. I max out around 12 miles with modest (non sweating) peddle assist.

LifePo4's don't need baby sitting like lipo's do. But LifePo4s are expensive. They will however last for 3-4 years depending on how you treat them. When I switch over to LifePo4's I will probably go with a know business like: http://www.emissions-free.com because when you send your money to China, you will want to be sure that you are getting what you pay for.

I have built my own battery frames in the triangle of my bikes. I make them out of wood because scrap wood is free, fairly light weight and rigid. Battery bags do look good though.

Hope this helps.

Here's some recent threads for you to check out,

http://endless-sphere.com/forums/viewtopic.php?f=3&t=33615

http://endless-sphere.com/forums/viewtopic.php?f=3&t=34294

http://endless-sphere.com/forums/viewtopic.php?f=3&t=36378

http://endless-sphere.com/forums/viewtopic.php?f=3&t=32364

Think you would be happy with a front mounted geared "mini-motor" and a small[ish] Ping battery.
It's the easiest[plug and play]set-up you could do.

Multitude of ways to get what you want. This would be the cheapest, yet as reliable as any, and more so than some.
http://www.walmart.com/ip/NEXT-Parowan-26-Men-s-Mountain-Bike/17252251
http://www.ebay.com/itm/48V-500W-26-Rear-Wheel-Electric-Bicycle-Motor-EBike-Scooter-Cycling-Hub-Engine-/390393477398
For such a short range, 5ah of 12s lipo will keep you close to legal and give you 10 mile range at 20mph with no pedaling. Cost under $150 with 6s lipo charger. Easy to extend range by just adding more lipo to it if you need it. Battery pack will weigh 3 lbs and you can carry it in your hip pocket. Two of these for 5ah 12s.
http://www.hobbyking.com/hobbyking/store/__16207__Turnigy_5000mAh_6S_20C_Lipo_Pack_USA_Warehouse_.html
Total cost ~$450
Would you please go to the user control panel and enter your location. Thank you.

Talk about easy. 6 mile round trip if you take the long cut. Heck, that's still no prob for sla's. Not that you want to lug them around. Since you only want 20 mph, I'd say go with a lower power gearmotor rather than a dd. Something like 350w will take you to 20 mph with little to no pedaling.

By going for a low wattage kit, you don't need a lot of battery to run it. So a smaller 36v 10 ah lithium battery would be fine. A pingbattery is often my recomendation, but others would do just as well. Perhaps a waterbottle shaped one, or other limn chemistry option. The smaller battery from cellman would work fine as well. A123's are quite good.

Thanks for the input guys, it has been very helpful.

After reading and thinking a bit, the geared motor does sound better now. Originally I was in favor of the DD since they are simpler, but I do intend to pedal the bike a good bit so the resistance would be annoying. The DD seems like a better setup if you plan to motor more than pedal.

The offerings from cell_man are appealing and would likely be where I get the motor/kit. The MXUS motor might be good for a front mount option, but for the rear I'm not sure what the drivetrain options are. Since it is so small I would hope that you could get a decent set of cogs, I just don't want a single speed so a set of 7+ would be nice. I like the price and size of the MXUS, but am a little concerned that i would quickly want the MAC. Not sure why cell_man offers a MAC 500 kit but not the 350, is the 350 not really worth it (i.e. go with MXUS if you want something less than 500)?

I might give the front mount some more thought, but still leaning towards rear. I do like the idea of a quicker swap back to normal bike mode (although I don't think pulling the rear is that big of a deal really) and a more common drivetrain (probably the bigger plus). If the stealth aspect becomes and issue there is always the possibility of front panniers, although that puts the motor and cargo in the same location - a location that I've never put anything before.

For batteries it is coming down to LiPo or LiFePO4. I'm a little apprehensive about frying the LiPo, but like the size, price, and configuration flexibility (especially since I'm new and not settled on a complete ebike system); need to study these more to get confortable with the risk. On the other hand, the LiFePO4 is appealing because it is safer and supposedly lasts longer. I'll have to run some rough numbers to see how much extra I would be willing to pay for the LiFePO4 versus how much longer they might last.

With both of these battery types one factor that I think is significant is how the charging cycles are best managed for battery life. The more flexible a battery system can be when being used, left sitting, and being charged relative to current charge, the better it is in my mind. I would like to be able to not have to worry much about draining them fully before the recharge (or not) or having them fully charged before.

For battery sources, depending on what type I decide to go with it will probably be cell_man, Ping, or LiPo from Hobby King. This part definite needs more thought.

Hopefully this will turn from a "considering" thread to a building thread.

bc_dc said:

I might give the front mount some more thought, but still leaning towards rear.

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I have a front wheel drive motor. From now on, I will only consider a rear wheel kit.

I originally bought the front wheel kit for simplicity. I was thinking that it was going to be easier to use then tuning a rear derailleur to shift properly. I was wrong. I can now say it was not the best choice. So you live and learn.

A) the small amount of metal in the front forks necessitates two torque arms to insure safety.
B) If you decide on non-suspension forks, the pounding on your body will will take will make your spine ache every time. I just retired a non-suspension chromoly steel Trek for that reason.
C) If you decide on front suspension (something I highly recommend!!!!) you my need to modify the fork by grinding some of the material out of the fork axle slot to center the axle. How are your machining skills?

In the long run, for simplicity and safety, a rear wheel drive is my next choice.

As soon as you said, " converting back to a regular bike easier" a red flag went up.

Leave your regular bike alone if you like pedaling most of the time. Get a cheap used bike and slap a motor on that one. The motor or the bike could be anything for a ride that short. It's not like you'll see a big travel time difference between 15 mph and 30. If the cheap bike is a coaster brake beach cruiser then go front hub. No point in spending a fortune, so cellmans little gearmotor would be fine. It will run on less battery, saving you more money. Don't sweat gears, you'll end up leaving the bike in one gear, likely the highest. You need a selection of gears still, but you won't be shifting like you used to.

The advice would be quite different if you had a 10 mile trip to work. But seriously, anything will get you there for 1.5 miles. I'd be tempted at that distance to just get a $200 stand up scooter for that.

dogman said:

As soon as you said, " converting back to a regular bike easier" a red flag went up.
Leave your regular bike alone if you like pedaling most of the time.

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I agree with dogman about all of it except the stand up scooter part. I don't know if I could show up at work on something like that.

An inexpensive MTB with a large triangle and front suspension is my recommendation. My first bike cost me $55 USD with no suspension. My Second bike with front suspension cost me $120 USD and I probably paid too much. :?

I just liked the way it looked. 8)

I shift gears around here, but usually just the front chain ring. I don't need to change the back gears much.

As for the size of your kit, I am thinking like this....
1.5 miles at 10mph = 9 minutes
1.5 miles at 15mph = 6 minutes
Ergo, a small motor and small lifepo4 pack is enough.

But I have to warn you....Once you get you ebike going, you will have so much fun on it you will only want more!

Have fun with it!

The nice thing about LiFePo4 is that you plug the packs into the charger and you are done. With a LiPo pack from hobbyking you have to pay a lot more attention. I'd suggest LiFePo4 packs for beginners who don't want to get into a mess of wireing etc. Or, if you go lipo get a 10s pack wiht a 10s charger so you can balance charge every time, and not have to reconfigure the pack for balancing.

My advice is golden. Just ask anyone.




That said, we all know that every boy should have a dog. Likewise, every boy should have a bike....a regular bike.

Having an ebike should be in addition. But keep a regular bike so you can enjoy riding, lift it easy, throw it around, etc. On beach vacations you don't need electric. Just have fun.


With that out of the way, Welcome to Endless Sphere, the number one (without any debate) E-bike website in the world. These guys (not including me) are the best and will teach you much. They aren't snobs, and they are helpful to newbies like myself.

I started on bikeforums.net, and it's a great site, but not so good for ebikes. I started to wonder if ebikes were actually being ridden or if people were just buying cheap crap on Ebay, trying to make it work, and then giving up. I researched for a long time and really started to think it was just too emergent to work.

But when I stumbled onto Endless Sphere (I forget how), I learned that people really are making ebikes that work and that last years.

And now, 1.5 years later I've made three builds that work.

I've yet to build the bike I really want, but I'll get there. I'm still in SLA mode (I should know better but I'm a cheap skate).


The only decent advice I can give is this: Don't spend any money until you really know what you want. Research like crazy.

I was hasty and could have done better, based on how much money I've spent.


My dream ebike for commuting: A nice Trek Soho-type bike (city commuter) with a lifepo battery (48volt, 12-15ah) and a rear-wheel direct-drive hub motor, thumb throttle, and that's it. Battery in the frame. Nice and easy.

My other dream bike is a Trek Fuel (full suspension) with the same setup as above.

That way I can do the fast on-road thing and the crazy off-road thing.

Right now I have this. The bike was free (piece o' crap Wallmart Schwinn) with 500-dollar kit from EbikeKit.com

It has about an eight-mile range if I pedal some and I'm on a smooth surface. Offroad it can comfortably do about five miles under full power and little to no pedaling. It takes about two hours to charge. It weighs slightly more than the space shuttle but a good deal less than the Titanic.

It works great...no issues. I still have to add the front brakes (long story...had to remove them, etc.), but it works great. It's reliable and strong. There's really nothing to break because I haven't gone overboard on anything. It's a 48-volt battery (only 9ah, which means it has a shorter range--about 8 miles) and a 500-watt motor called a 9c (the motor can run a little higher than that without worry, but my setup is pretty stock...no overheating worries) and it's a 22amp controller that came with it, which is fine for my power level.

Then, a bunch of zipties, velcro and electrical tape. I made a platform out of a rear bike rack and attacked it to the water bottle holes, reinforced it with whatever I had in my garage, and put it all together. Nothing moves or wiggles.

Total cost: About 600 bucks.

The only difference of assembly with a rear motor is the freewheel, and maybe the dishing of the wheel. Little trouble for the benefit of propulsion, that is a much more natural riding style on 2 wheels, and definitely better on slippery surface.

Just to clarify, I have a regular commuter bike that is staying regular for the time being, so the GT frame that is coming is just for the ebike and will not impact my regular ride. It is a Montague folding mtb, the one with the giant top tube and no downtube (Swissbike, Hummer, Paratrooper etc) set up with big chainrings, 1.5" street tires, fender, rack/panniers and all that commuter stuff.

My mind got a bit carried away with a few things. There are a lot of cool things I could do with the GT frame which made me think of having an easily reversable ebike setup, but, as you guys said, it is better to use different bikes (I could always pick up another frame).

Also, I let a bit of scope creep occur since I'm getting pretty excited about an ebike and already started thinking of configurations for more power and cargo - like an xtracycle, rear DD motor, and decent amount of batteries to really be a care-replacement. But that should come later, right now I should stick to pedal assist to extend the commuting season, so thanks for keeping me honest!

As for batteries, I went through some more of the info here and am convinced that the LiFePo4 is the right choice, I don't want to burn down half the neighborhood...Maybe I'll work up to it someday, but for first build a more plug and play LiFePo4 will do. And, since I don't need much power to meet my minimum distance/speed targets it won't be a huge pack anyways.

Using the handy equation from Ziggurat's thread: Capacity (in Ah) = km * (Wh/km) / V * 1.25, if I assume a worse case of 9.6 km (6 mile round trip) and 20 for Wh/km (no pedaling, windy) and a 24V system returns a need for exactly 10Ah. If this is correct, then the Ping 24V 10Ah battery for $219 would be able to handle my worst case round trip commute. Realistically, in the heat of summer when I'll want the ebike I'll mostly be taking the short route there and still pedaling on the way home (don't care if I sweat on the way home). If I understand things correctly, I'll probably be running under 1C much of the time anyways and only for 10 minutes or so each ride, so this pack should be enough (for now...).

So, I'm thinking the Ping 24V 10Ah pack with included 4A charger (http://www.pingbattery.com/servlet/the-4/LiFePO4-Lithium-Iron-Phosphate/Detail) and the cell_man MXUS rear kit (http://www.emissions-free.com/catalog/i16.html) should get things moving for under $600 shipped. Other stuff needed would be some sort of display for battery telemetry and whatever bags/mounting hardware for the battery pack and motor controller.

Does that sounds like a decent package for getting a newbie on the road?

MikeFairbanks, I went through the same process as you did - looked around bikeforms and got discouraged (excellent regular bike content) and then somehow stumbled my way here through a search. Lucky search results on that one!


Thanks again, everyone.

bc_dc said:

Using the handy equation from Ziggurat's thread: Capacity (in Ah) = km * (Wh/km) / V * 1.25, if I assume a worse case of 9.6 km (6 mile round trip) and 20 for Wh/km (no pedaling, windy) and a 24V system returns a need for exactly 10Ah. If this is correct, then the Ping 24V 10Ah battery for $219 would be able to handle my worst case round trip commute.

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I'm one of the few people on here that is usually trying to get people to stick to lower power, but here I have to say I don't think you'd be happy with 24 V (pretty low top speed). I've got the MXUS front geared 350W and it does about 18 mph top speed on 36 V. I wouldn't recommend to anyone to go less than 36 V.

My setup is very similar to the one you are heading for, except I've got the front hub motor. I get 6.5 to 7 Wh/km pedal assist. One day I tried briefly no pedalling, and from the CA it was probably somewhere around 10-12 Wh/km. Even at 20 Wh/km, on 36 V, you wouldn't need 10 Ah. I can ride 18 km round trip on about 3.2 Ah (with medium pedalling). If I were starting again, I would probably look into a custom A123 battery from cell_man. A 12s3p might be lots for you (3 * 2.3 Ah, 6.9 Ah total). Relatively small and light, and much safer than LiPo. I'm not sure of his prices for custom packs, but I don't think that would cost a lot more than the ping you mentioned. And you'd have a "future-proof" battery where you would never worry about C rate. One option to explore, anyway.

You should consider a lithium manganese battery. Ive got one and i can tell you It's a lot lighter than lifepo4.

I agree, 24v won't cut it and even might not run at all on a 36v controller.

36v 10 ah ping, and a little gearmotor. However,,,, now that you want more speed, more distance, more cargo carry ability later everything changes.

I'm not sure just what to say now. Definitely tempted to tell you to go for a larger motor, and much larger 48v 15 ah battery. But what to buy matters so much on exactly what ride you intend that it gets hard to say what you should get.

As a car replacement, a longtail is great. Especially if 20 mph is fast enough for you. With the right motor, you can haul an amazimg amount long distances. My longtail runs a slow 2810 winding 9 continent motor. 18 mph on the big high drag longtail, but it gets amazing long range. The same motor run on 72v makes a good trail bike or faster commuter, with zippy take off from stop signs or nice hill performance.

But for you, maybe sticking with gearmotors would be best. So you can pedal freeweeling when you want to. So now I lean towards advising you to try the Mac Rear hub and the A123 48v triangle battery from Cellman. Get one with medium fast winding, like the 8t, not the fastest one or the slowest one. But now there is another problem, to carry the battery in the triangle you need to have a triangle.

I just quadrupled your budget, including a different bike. You're welcome.

Ah, now the world is in its proper orbit, with me trying to hold back the high-power talk for someone who started out looking for assist

I don't think there's anything wrong with starting small. I did, and I don't regret it at all. I've now got the Mac 8T (still in the box at the moment) but I wasn't really hungering for more power -- just wanted another ebike, to have a backup while I'm working on one, or to have two to go riding with my wife or to give one to my son. Really I just wanted to explore. All the knowledge and the pieces are reusable, or at least easily transferred to another bike or another person.

+1 for considering LiMn. But for any battery type, be aware of the C-rate capabilities when shopping around. If you want to future-proof, in your situation I'd say your best bet is to get a higher C-rate capable battery. Then even if you go power-hungry, the battery will still work for higher amps. If you want to go farther, you can simply add another. You wouldn't even necessarily need to parallel them, just carry the second one when you need to go farther, and switch once the first one gets low. Or for a high-voltage DD motor setup, add another 36 V in series. Higher C-rate capable = More modular in a way you can't do with low C-rate batteries. The lower-C rate stuff really shines for someone who must go a long distance, and they are getting big capacity anyway.

Jason - could you recommend a source for the lithium manganese batteries? I'm not really that concerned with the weight, but if there aren't too many other compromises it would be good the check out.

dogman - What I meant by my last post was that I could see an longtail-car replacement ebike in my future, but it is probably not a good idea to jump into that just now. I don't know how well an ebike will work until I build one, don't know how the police will react to a fast bike, and need to seriously evaluate the trips I could do on a big ebike in my area before taking the plunge. One thing that concerns me with a true car replacement bike is that most places in my area (grovery store, post office etc) don't have bike parking, so I would have to be looking for trees/signs to lock the bike to. I work at a pretty secure facility with ample bike parking, so no issues there. For the bike, the downtubeless Montague is my current commuter that I plan to keep regular, the GT frame I have on the way looks like this: http://velospace.org/node/33433, so with a strong streel triangle I should be able to convert it to a more powerful setup in the future; I could always put the MXUS kit on a different bike if I really want to longtail the GT, or just get another frame off ebay again (plenty of decent deals there). I think the biggest thing in staying with an assist bike for now is the price, I'd rather spend $600 to take the chance on a simple ebike rather than $1200, even if it means building more bikes in the future.

dogman and Ziggurat - Would the 39V 9.2Ah cell_man A123 kit for $350 be a good choice for the MXUS rear hub for the pedal assist setup or should that be fitted with the MAC 350W? It isn't that much more than the 36V 10Ah from Ping, so I would be willing to spend the extra $30 for the good reputation of the A123.

bc_dc said:

I don't know how well an ebike will work until I build one

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How true, how true....Nube to nube you don't know until you build one. Once you build one, you will be knowing.

Do you intend to have front suspension? If not, fat tires are a must. 2.somethings.
Also consider a suspension seat post. Even with a small motor and battery pack, you are adding weight and inertia that will rattle your body with every bump.

Also, IMHO, it is better to have a bigger motor, give it less juice and ride with-in the limits of the law then wish you had spent a few more dollars on a bigger motor because you are forced to peddle when you don't want to. My controller, which uses hall sensors won't really allow the bike go past 20 mph anyway.

My recommendation: get the bigger motor, make sure your speedometer is calibrated and just cruse-it while enjoying the ride.

bc_dc said:

dogman and Ziggurat - Would the 39V 9.2Ah cell_man A123 kit for $350 be a good choice for the MXUS rear hub for the pedal assist setup or should that be fitted with the MAC 350W? It isn't that much more than the 36V 10Ah from Ping, so I would be willing to spend the extra $30 for the good reputation of the A123.

Click to expand...

That battery would be great for the MXUS, a Mac 350 W, and even for a Mac 500 W. More than you need for the MXUS, but that doesn't hurt anything, and gives you options for the future. Just make sure it fits your needs in terms of size/shape (can it fit in the triangle) and weight.

So now I am going to scale up a bit in the power advice and join dogman's (and others') thoughts because you seem to be very focused on being able to scale up later... if you seriously are thinking of going to higher speeds, you may later wish you had a 48 V battery. You'll have to decide if that is what you want. Cell_man's website lists typical speeds achievable on 36 V and 48 V for the Macs. For the MXUS, it doesn't recommend going above 36 V, but some have done so without problems, at least none that I've heard of. I tried it a couple of times, IIRC I got about 35 km/h on 48 V. Go out with a bike speedometer and look around (carefully) while going down a steep hill at various speeds, imagine going that fast all the time on the flats, even up a hill. Might give you some idea of what you are comfortable with.

On the battery price, note that the BMS is included in cell_man's prices, but not the charger, so add another $50 for that (or more for the higher amp charger).

You'll really have to think what you want ... I knew I wanted to get in with something simple and low cost, and the MXUS and 37 V were good for that. I also knew that I truly could resist the draw of higher speeds. But that's rare on here, almost everyone hungers for more power once they get started. If you think that's you, then maybe go for a Mac and 48 V, and program the controller (or use a CA) to limit the power for assist if you find that is all you need.

Ziggurat and others are so right about the addiction to power being an issue for many. My last build could do 28mph on the flats and it didn't feel like enough after a while. Part of the problem is hills. Once you're used to maintaining 28mph on the flats you want it on the hills too.

And then there is the commute time. Pedaling took me 35 minutes to get to work. My first build took it to 25, followed by 20 minutes, and now it's 15, but I found another shortcut and I know I can get it to 12 if I disregard my personal safety.

I was certainly considering the ability to scale up later, but it probably came off as more important than it actually is. I live in a very bike-unfriendly area and most of the places I go are still within a 3 mile radius, so any plans for more power and speed would be a ways down the road. The bike I'm using has a rigid steel fork, and I do plan on running the largest Schwalbe Big Apples that will fit (2.15-2.35), but I don't think flying along at 30+ mph on a rigid with a bunch of extra weight is a great idea anyways. There are only a few bikelanes in my area and nobody respects them, so I would be on the sidewalk/shoulder most of the time. Since the sidewalks are rough and the shoulder is rough and full of debris/grass growth that would tend to limit speed as well.



I'm going to contact cell_man to get the physical spec of the 39V 9.2Ah battery, and if that fits I'll probably do that with the MXUS. If I do end up wanting more later on I could always build a new bike either with a new frame or swap kits between frames to get the best setup. Shaping this project, which is very new and variable, to suit future projects that are even less well known is probably not a useful exercise anyways. It is hard to pick out what I really want in the future when I haven't even tried anything today.

bc_dc said:

Jason - could you recommend a source for the lithium manganese batteries? I'm not really that concerned with the weight, but if there aren't too many other compromises it would be good the check out.

dogman - What I meant by my last post was that I could see an longtail-car replacement ebike in my future, but it is probably not a good idea to jump into that just now. I don't know how well an ebike will work until I build one, don't know how the police will react to a fast bike, and need to seriously evaluate the trips I could do on a big ebike in my area before taking the plunge. One thing that concerns me with a true car replacement bike is that most places in my area (grovery store, post office etc) don't have bike parking, so I would have to be looking for trees/signs to lock the bike to. I work at a pretty secure facility with ample bike parking, so no issues there. For the bike, the downtubeless Montague is my current commuter that I plan to keep regular, the GT frame I have on the way looks like this: http://velospace.org/node/33433, so with a strong streel triangle I should be able to convert it to a more powerful setup in the future; I could always put the MXUS kit on a different bike if I really want to longtail the GT, or just get another frame off ebay again (plenty of decent deals there). I think the biggest thing in staying with an assist bike for now is the price, I'd rather spend $600 to take the chance on a simple ebike rather than $1200, even if it means building more bikes in the future.

dogman and Ziggurat - Would the 39V 9.2Ah cell_man A123 kit for $350 be a good choice for the MXUS rear hub for the pedal assist setup or should that be fitted with the MAC 350W? It isn't that much more than the 36V 10Ah from Ping, so I would be willing to spend the extra $30 for the good reputation of the A123.

Click to expand...

The MXUS geared, the Mac motors and the A123 battery from Cell_man are all good proven products and Cell_man is provides a great service, but if you really are serious about building a decent assist Ebike for $600, you need to look to BMS Battery.
Just recently, a few more or less favorable reports concerning the LiCoMg are trickling in here,

http://endless-sphere.com/forums/viewtopic.php?f=14&t=33566&start=45

Yes, Rassey had to replace the BMS in his 48V 20Ah pack, but now it seems good. Note the very favorable review of the 48v 10Ah pack[more fav. reviews on this pack @ Pedelecs. UK].
The motor I would suggest to go with a LiCoMg 48V 10 Ah battery is a better known product. The Cute Q100[36v/350W, 201 wind] is much the same as the MXUS in terms of size and performance[i linked 2 build threads using the Q100 previously]. The motor is available frt. or rear and the rear is capable of accepting freewheels up to a 9-speed.
Q100 kit-$134
Battery-$259
Shipping to the States-$132
Total-$524
The A123 is more battery than a mini needs, overkill. A Mac is very happy with a A123, but the speed increase comes with a exponential[well, almost] increase in $$$.
Which do you want, a 22-23 mph assist bike or a 27-30 mph bike where pedal assist is pretty much optional?

A 22-23mph assist bike is what I'm looking for.

I was pretty settled on the MXUS with some type of A123 battery, 36V 9.2Ah or smaller, but....

Found out that back in the old days mtb frames had 130mm dropouts rather than 135mm; of course this revelation came after purchasing the frame. So now it looks like I either would have to just squeeze the wheel in there and hope that it doesn't tweak the frame, cold set the frame, or respace and redish the wheel. I think remaking the wheel is probably the safest thing to do, but I haven't done any wheel building and may need to take it to the local shop. Might get a practice wheel to try my hand at.

Either that, or find another frame to work with. Unfortunately I'm not finding many relatively late model steel mtbs laying around.


Also, do any of you guys know what, if any, import duties are levied when shipping these things from China to the US? Also, how are the logistics when importing as far as deliverying the package once cleared through customs? Does the international shipper bring it all the way to my door, is it transfered to UPS/Fedex, or do I have to pick it up at customs?