Another confused noob

[thatguy]

Hello, complete noob and want to build an ebike to commute to work. First post after reading the stickies and a dizzying amount of info from this forum.

It's 30km (18.6 miles) round trip, hills in both directions. I currently find it difficult to bike to work because 1) I sweat from the hill climbing, and 2) it takes up too much energy if I bike every day to the point that I become too tired for my other passions.

My requirements are 1) not interested in speed, I want to pedal 70% of the way without breaking into a huge sweat on the hills, 2) I would like the ebike setup to be light as possible because I usually travel with a load in my panniers and I have to carry the bike up and down a flight of stairs for storage (I'm 150lbs plus 25lbs of equipment and groceries), 3) I would like to make use of a hybrid bike I own (Kona Dew FS) and be able to keep the current gear and drive train intact, and 4) sub $1,000 if possible.

For these reasons, I'm leaning towards a front geared, brushless, 250w hub motor to keep it light and resistance free while pedaling. Is this motor a problem for the stock aluminum suspension fork? If so, is it better to find a steel suspension fork, or go with a rear geared 250w hub motor instead?

In terms of the battery, I would assume a minimum of 36v? What amp hours would I need? If I later decide to build a second ebike with the gng mid drive, would it be better to get a beefy battery now so I can share one battery between the two ebikes? For example,is it possible to get a 48v battery for a 36v rated motor? For newbies who don't know how to DIY a battery, what is best bang for the buck and where to buy? Battery forum seemed a little too technical for me to understand.

What would you change given my criteria? Any advice is greatly appreciated. Thanks for any insight!

 

[melodious]

I'd go with 48V. There is a high likelyhood that the stock controller for that motor can handle voltages above 36V, typically maxing at 60V, but you verify this by checking your controllers capacitor ratings. I'm sort of in the same situation. I have a GNG gen2 48V system and a future Ezee V2 bike build and need a battery that can handle both motors. Your in Vancouver, just ride on over to Justin's shop and give them a holler and check out what's available for purchase. It's so much nicer (and satisfying) to consult with a real person in front of you.

 

[Ykick]

That's a long commute but you've done it pedaling so you have that going for you. Definitely consider 48V 250-500W geared hub equipment. 20 miles will be tough to carry enough battery even with a low power efficient setup. 36V 20Ah would almost certainly do the round trip job but that's a BIG HEAVY battery pack. 36V 10Ah might do it with much pedaling but for how long? No battery ever increases range and capacity as it ages.

48V 15Ah battery would be a good compromise to attempt the full round trip with pedaling.

Charge at work an option? I wouldn't carry a charger (especially if it were my only one) but if an extra can be stowed at work 'gonna cut range requirement and thus battery size in half.

If you can put the battery in triangle I'd spec a rear motor but if the battery is on a rear rack, front motor will better balance things out and be somewhat easier than dealing with rear derailer and freewheel.

 

[e-beach]

Hello, complete noob and want to build an ebike to commute to work. First post after reading the stickies and a dizzying amount of info from this forum.

Welcome to ES! Yes the info here can become dizzying, but we can help you get it straightened out. I see you live in Vancouver, BC. That makes you lucky enough to be able to visit Grin Technologies 20 E 4th Ave Vancouver, BC. They are you local experts. I don't use there stuff because I am a poor man and find them to be a bit pricy, but they are very-expert on e-bikes and there stuff works. If I lived in Vancouver I probably be on a first name basis with them. I recommend you go and check out what they have.

It's 30km (18.6 miles) round trip, hills in both directions. I currently find it difficult to bike to work because 1) I sweat from the hill climbing, and 2) it takes up too much energy if I bike every day to the point that I become too tired for my other passions.

I roll around on an 80lb ebike, I weigh about 207lbs at the moment and find that a15ah battery pack will take me about 20-22 miles with little peddling. My kit is a yescomusa 36v 800w front hub motor. I run on headway lifepo4 batteries that I got from headway headquarters in Washington State, USA.

My requirements are 1) not interested in speed, I want to pedal 70% of the way without breaking into a huge sweat on the hills, 2) I would like the ebike setup to be light as possible because I usually travel with a load in my panniers and I have to carry the bike up and down a flight of stairs for storage (I'm 150lbs plus 25lbs of equipment and groceries), 3) I would like to make use of a hybrid bike I own (Kona Dew FS) and be able to keep the current gear and drive train intact, and 4) sub $1,000 if possible.

Your bike looks like a fine bike for conversion but e-bikes are always on the heavy side. You have a nice open trangle for a battery pack. I always recommend putting as much weight in the triangle vs the rack for optimum handling. Too much weight on the rack makes the bike unstable.

For these reasons, I'm leaning towards a front geared, brushless, 250w hub motor to keep it light and resistance free while pedaling. Is this motor a problem for the stock aluminum suspension fork? If so, is it better to find a steel suspension fork, or go with a rear geared 250w hub motor instead?

A 250w hub motor isn't going to give you much help up a big hill. A 250w bottom bracket motor might because you will be able to use your gears. Personally I wouldn't waist my time with a 250w hub motor unless your laws require it and you are worried about getting caught. Also, if you want to use a dremel tool or even hand file to carve out about 2.5mm of materiel out of your front fork dropouts to center-up the hub motor 14mm axle then go with a front hub motor. It is a pain in the ass to do, I know because I did it on my bike. If I had it to do all over again I would have used a rear hub motor. I recommend you go with a rear hub motor on your first build. It is easier and safer in the long run. Here is a link of how I did my conversion "on the cheap"
http://endless-sphere.com/forums/viewtopic.php?f=3&t=39690

In terms of the battery, I would assume a minimum of 36v? What amp hours would I need? If I later decide to build a second ebike with the gng mid drive, would it be better to get a beefy battery now so I can share one battery between the two ebikes? For example,is it possible to get a 48v battery for a 36v rated motor? For newbies who don't know how to DIY a battery, what is best bang for the buck and where to buy? Battery forum seemed a little too technical for me to understand.

A good battery pack is where you will spend the bulk of your money. I run on lifepo4 because of their reputation for safe chemistry. rc lipo will give comparable AH and better current delivery (c rating) with lighter size and a smaller package for a cheaper price, but sometimes rc lipo catches on fire.
In regards to 36v motor and 48v battery pack, yea you can over volt the motor, but it could burn out on a hill. You would need a controller and bms compatible for 48 volts.

If I were you I would start by going over to visit Grin Tech and see if they can help you out. It is a luxury most of us don't have.
http://www.ebike.ca/contacts.shtml

Hope this helps.



What would you change given my criteria? Any advice is greatly appreciated. Thanks for any insight![/quote]

 

[thatguy]

Wow, thanks everyone for the replies and a pleasure to speak with great minds! You guys have raised some interesting points and given me a lot to think about. Sorry, didn't realize until now I posted under EV instead of Ebikes. Is there a way to move this thread over?

A bigger battery/motor let's me account for going from girlfriend's place to work which is an even greater distance of 40km (24.8 miles) round trip. Going small and light allows me to pedal home even if the system fails; my fear is getting stuck far away with a 100lbs setup and no way of pedaling it uphill. Has that happened to anyone? Having said that, I'm wondering if I'm jumping in head first with a bigger system when I should start with a smaller one since my intention is to have a second bigger system later on. The reasoning is that if I have two ebikes, I can pick the right bike for the right situation. How is my dog going to keep up, lol!

Given I have 3 destinations (my place,girlfriend's place and work) sounds like I need a minimum of 2 chargers regardless (thanks for the heads up Ybikes). If I were to plan for 2 ebikes, I would want the smaller one on the light hybrid 700c wheel, and the bigger setup on a heavier more durable mountain bike. It sounds like I should have two separate batteries now. Can lifepo4 and rc lipo batteries share the same chargers? Hoping to have 2 chargers instead of 4in the long run.

Does anyone think I can get away with using the stock aluminum suspension fork with a 250w front motor and torque arms, or is that just wishful thinking? I don't mind getting some pedal exercise with the 250w front motor if I don't have to change out the fork nor touch the rear drive train. e-beach mentioned his motor has 14mm axles, is that normal for 250w front hub motor? In fact, why don't they make larger front hub motors with 20mm axles to make use of standard downhill forks?

Ok, so speak with the local experts, check the controller voltage rating, determine the battery size and type, marry the right kit with the right bike, and I'm done. I feel less dizzy now!

 

[Joseph C.]

A bigger battery/motor let's me account for going from girlfriend's place to work which is an even greater distance of 40km (24.8 miles) round trip. Going small and light allows me to pedal home even if the system fails; my fear is getting stuck far away with a 100lbs setup and no way of pedaling it uphill. Has that happened to anyone? Having said that, I'm wondering if I'm jumping in head first with a bigger system when I should start with a smaller one since my intention is to have a second bigger system later on. The reasoning is that if I have two ebikes, I can pick the right bike for the right situation. How is my dog going to keep up, lol!

Given I have 3 destinations (my place,girlfriend's place and work) sounds like I need a minimum of 2 chargers regardless (thanks for the heads up Ybikes). If I were to plan for 2 ebikes, I would want the smaller one on the light hybrid 700c wheel, and the bigger setup on a heavier more durable mountain bike. It sounds like I should have two separate batteries now. Can lifepo4 and rc lipo batteries share the same chargers? Hoping to have 2 chargers instead of 4in the long run.

Does anyone think I can get away with using the stock aluminum suspension fork with a 250w front motor and torque arms, or is that just wishful thinking? I don't mind getting some pedal exercise with the 250w front motor if I don't have to change out the fork nor touch the rear drive train. e-beach mentioned his motor has 14mm axles, is that normal for 250w front hub motor? In fact, why don't they make larger front hub motors with 20mm axles to make use of standard downhill forks?

Ok, so speak with the local experts, check the controller voltage rating, determine the battery size and type, marry the right kit with the right bike, and I'm done. I feel less dizzy now!

250 watts is a very small motor for hills. You have to remember that a hub motor doesn't have gearing. Its the equivalent of cycling up a hill in a high cog. Hard work for a small motor.

If you want to go Lipo you need to understand what you are getting yourself into. They are not 'plug-and-play' and can be potentially very dangerous.

Putting on a rear motor is actually quite easy. You only have to take off the wheel going near the derailleur is completely unnecessary. Grin Cycles is the place to go to - there are one of the world's foremost experts on ebikes.

 

[MattyCiii]

Do municipal busses in your area have bike racks up front? I've used the local bus a few times as the "contingency plan" way home when things go wrong (for my folding bike - my A-Line would not fit on a bus bike rack!)

 

[dogman dan]

First thing to adress is can you charge at work. If so, you can easily do the commute on a smaller battery, perhaps as small as 10 ah of 36v.

Next the hills. I can't recomend more power for the hills too much. 250w sounds like a lot of help, but on a steep enough hill you won't see more than half of it reach the rubber. The rest will make heat. A kit with a 48v 20 amps controller, about 1000w input, will give you 5-600w at the rubber, and then you will make it up hills up to 7% grade with no pedaling. Plus, you'll be able to make it up that hill, with pedaling, on that sucky day that you climb that hill into 30 mph of wind.

The motor and the forks, are perhaps the trickyest problem. Many suspension fork designs simply have the tubes too close together to permit the use of many of the gearmotors. But the same fork may be able to fit a direct drive motor. The 9 continent motor sold by Grin cyclery has enough space between the two covers for use with many suspension forks.

Fitting the motor safely to alloy suspension forks is really for experts, but if you have the ability to see rather than merely looking like most folks you can do it properly without being an expert mechanic. I'll link you to some threads I wrote explaining the procedure when the time comes for it. For now, just know that you need two of Grins good torque arms and two C washers, and you will need to file the fork dropouts deeper by about 1 mm.

The other option is to replace the fork with a rigid steel one, such as the suspension corrected fork from Surly. Or use a different bike, with a rear motor. Does your bike have an internal gear rear hub? If not, just run a rear motor on your current bike. 9c motor, 48v battery, 20 amps controller.

Lastly the weight. You could keep it really light if you want to, but less than 65 pounds is pretty hard to do if you want real range and ability to power up those hills. You might have to practice carrying the battery and the cargo up those stairs in a seperate trip.

 

[melodious]

I see no problem with this person using a smaller motor because he will be contributing to the motor via legwork. Remember, he isn't a wimp. He has done this many times over, without assistance of a motor. As long as he realizes this motor isn't going to do all the work for him he should be good. Also, the burning sensation in his thighs and calves will be gone once assistance is installed. That's a giant mental hurdle. Personally, I think a 350 motor (it's a tad larger than the 250s) is the motor to start with, especially with 48V battery/20amp limited controller.

My 350motor (high RPM version) in 20" wheel on 36V battery/15amp limited controller get's me anywhere in my 25 mile radius. There is a 1 mile long graded hill (5-6%?) and has no problem getting me up there as long as I contribute via legwork. If this hill were part of my daily commute, I'd have no problems tackling it with my current ebike setup.

I'm not trying to sell you on this motor though. Here's something to think about. A bigger motor than either the 250s or 350s are the 400-500s and more(Justin's geared Ezee v2 for instance), give you more motor so you have more upgrade potential into the future. Want to increase your battery from 48V to 60V on it? Sure. Want to upgrade the amps from 20 to 25 or 30? Sure. Doubt you could have as much upgrade potential in the smaller motors without risking an overheating event.

 

[thatguy]

With regards to batteries, I will stick with one type to keep things simple (thanks Joseph C). I assume the simplest and best bang for the buck is lifepo4 batteries at the moment. I here about li-nmc and lipo but if they are not "plug n play" then they are not beginner friendly yet.

One reason why I don't want a rear motor hub is I don't want a 8 speed freewheel. Any issues with a 9 speed chain to a 8 speed freewheel? Has anyone had success with attaching a 9 speed freewheel?

So each motor brand and size can have different clearances and may need adjustment, including filing down dropouts. I don't want to wreck my Kona Dew (it's the best looking bike I own, lol). Nor do I really want to add a steel front fork. If I went with a small (250w or 350w) rear motor, how likely will the rear dropouts need adjustment?

Charging the battery at work is not a problem. I can shave some pounds between a 36v/10ah and a 36v/15ah battery. Same is true for a 250w vs 350w motor. Although looking online some kits are being advertised as both 250w-350w motor?? Quite honestly, I still think the weight is more important than the extra help up a hill (@melodious, thanks for saying I'm not a wimp!). But it depends also on whether I'm saving 2 lbs or 10 lbs so the arugment is moot until I look at brand specs closely.

Thanks to all the replies on this thread, I finally feel like I have some understanding to narrow down what will work for me.

 

[dogman dan]

With regard to the motor size, I didn't mean to say he couldn't use a smaller gearmotor. I mostly wanted to point out two things.

One, the hubmotor gets into an inefficient rpm range if it slows too much on hills, so just when you need it most, up to half your power goes into heat. So on the steepest hills, there isn't much assist left if the wattage is really only 250w. No problems for 5% grades or less. I just mean real difficulty with grades above 10%, that are longer than a half mile.

Two, good luck finding a small gearmotor that even fits between the shocks on a suspension fork. I'm not sure what type you have, but you generally can't use ones that have a dropout centered on the shock tube. If you have forks with the dropouts positioned to the inside of the tube, then you might have clearance for a gearmotor. Again, the 9c dd motors have pretty good clearance at the covers compared to the gearmotors.

So your best bet might be the larger dd motor for that reason only. You'll have to file the dropouts, but only on the fork, not the actual frame.

My advice, do the front hub 9 continent motor kit from Grin Cyclery. Just make sure your install is immaculate and you won't break your dropouts. You may however have another problem common with front hub on shock forks. On my current commuter, the cheapie forks on it bind when the motor is pulling hard. So when I see a big pothole, I have to get off the throttle so the forks work nomaly when I hit the hole.

Pic of that commuter.

 

[dnmun]

if you have alloy for the front forks you have to worry about the failure of the dropouts on the fork.

so you need the C washers on each side to go into the recess in the dropout face, and then you will need a torque arm on each side capable of holding the axle in place when the dropout breaks off. this is a serious risk and can ruin your life or end it. you cannot torque the nut down too tight because the threads can strip so easily because only 1/2 of the threads are present.

 

[d8veh]

Here in the UK, most of us use 250W motors because it's the law - same as Australia and most of Europe. At only 150lbs, a 250w motor will be OK as long as you don't have exceptionally steep hills. With a 250w motor, you can get away with a much smaller and lighter battery. A 36v 10aH battery will take you about 35 miles aslong as you don't mind pedalling at the same time.

Fitting a 250W motor in aluminium forks is no problem. Many of the European bikes are like this even without a torque arm. Personally, I'd fit a torque arm for safety. You might have to file your drop-outs a bit to fit the motor. The new axle will be 12mm instead of 9/10mm, but is 10mm across the flats. This means that the new axle will be off-set from the centre. I always file my drop-outs deeper to re-centralise the axle. You don't have to do this, but you have to make sure that the first washer sits nicely in the dimple, which means filing off a bit of one side, otherwise, when you do up the nuts, the sideways force on the dimple will break it off -be warned!

I buy all my stuff (17 orders total $7000) from BMSBattery and have found them to be very reliable and they have a nice choice of batteries. For a 250w motor you can use a pedal sensor and it's best to have variable levels of assist, so this would be my shopping list:
http://www.bmsbattery.com/ebike-kits/423-bafang-250watts-front-driving-qswxk-motor-e-bike-kit.html
http://www.bmsbattery.com/36v/326-24v-lithium-ion-little-frog-abs-shell-ebike-battery-pack.html
http://www.bmsbattery.com/450-a-pair-of-ebike-torque-arm.html
Assuming cable brakes, 2 of these:
http://www.bmsbattery.com/459-hwbs-hidden-wire-brake-sensor.html

That comes to about $700 including shipping costs.

That battery will fit to any standard rack. Those bottle-batteries look nice but often struggle to provide enough current - especially the 8.8aH ones.
With these parts, you'll have to do a small bit of wiring - maybe change connectors etc. You can buy complete kits from suppliers that are easier because the wiring is plug-and-play, but their batteries are often low spec.

The speed of the above setup will be about 18mph. If you want more than that, you need to go up to 48v with the same kit, so you'd have to get the controller from somewhere else like Ebay or Elifebike; however, you'll lose a usable PAS function. A 48v 10aH battery would be OK.

Elifebike.com does more or less the same stuff and their shipping is a bit cheaper (I'm told). Their motor is 305rpm at 36v = 25mph, which might be a bit fast for efficiency and hill-climbing, but you can't have everything.

 

[dnmun]

that sun-thing28 guy on ebay also sells complete kits with the battery and motor for cheap. cheap cheap.