Building my first e-bike, questions

[Chalo]

Dropouts are technically bicycle rear frame ends that allow you to remove the rear wheel without first removing the chain (so, those with forward- or downward-opening slots). In common usage, the term refers also to other shapes of frame ends and to front fork tips as well. It doesn't refer to torque arms.

Most of the many e-bikes I have built over the years are front motor conversions. I think there are many advantages, but there are also limitations and I wouldn't use one with a suspension fork, or for conversions over 1000W in most cases.

Among the advantages of front hub motors:

- Pedal drive is completely independent of motor drive, and completely redundant

- The hub motor wheel (weaker) goes in the position that has lower structural demands

- It helps offset the strong rear weight bias of bikes generally, and of e-bikes specifically.

- It prevents pedaling force on the chain from damaging the side cover of the hub motor

- When pedaled, it gives two-wheel drive which helps with some soft surfaces and with climbing up onto steps and level changes

- It is the simplest and most expedient type of DIY conversion

Anyway, there's no reason to second guess your choice of motor layout. As long as you protect the fork tips with torque arms, and as long as the fork itself is up to the task, you should have no insurmountable issues with it.

 

[Diggs]

I can't even come close to reaching the ground from my seat. I highly doubt anyone with a good leg geometry for pedaling can.

Thank you! Watching everyone at the stop light put a foot down I was starting to think it was just me that couldn't touch while seated.

 

[Zambam]

Unfortunately, the front motor was already shipped2 days ago,($130) I had concerns about the gearing and derailleur being compatible in the rear hub motor, that's why I ordered it, The Pedelco e-bike (another old one) has front motor so I thought it didn't matter so much, which I chose.
I will have to see how it goes and I'll report what fails

At this point, just go for it. Check your dropout (fork tips) with a magnet. If it's steel you're ahead (your bike is supposed to have a steel frame, not sure if the forks are the same). Don't bother with PAS, use throttle in parallel with pedaling. PAS sucks it's so unpredictable, will get you into trouble sooner or later.

Your $26 battery is a good deal, 16" x 5.5" x 3" 9 lbs it's going to be difficult to mount it anywhere on your bike. Maybe put it into a back pack and see how it rides then find a smaller battery that fits the bike later?

Edit: I hope your kit has the motor laced to a rim already.

 

[fill]

Thank you! Watching everyone at the stop light put a foot down I was starting to think it was just me that couldn't touch while seated.

I was always told when in the saddle of a bike the optimum seat height was reached when your fully extended leg not stretched is at the bottom of the pedal stroke with the widest part of your foot over the pedal centre. so if you dont slip off the saddle when coming to a stop you will have to lean over a bit and extend a toe Just step back up into the saddle when you pull off.
- Just watch out for longer winter coats hanging over the saddle and snagging, stalling any attempts to slide off the saddle forward, if fitted with a dual direction zip a few inches of bottom opening can save you a stumble at a stop. ..

 

[Diggs]

Just watch out for longer winter coats hanging over the saddle

Heh - Mine's floppy summer shorts. Catching on the seat on dismount. Brought me to the ground a few times but at least I was stopped. I try to stick to padded riding shorts to avoid the problem.

 

[docw009]

That battery in a backpack? Kind of like carrying a gallon of milk on your back, isn't it?

There's all kinds of bike racks, I used to get these for $18, so I hate to pay more. It's sturdy though, and I adapted one to a rear swing arm on a suspension frame to carry 8 lb battery, It's just a matter of lengthening the front struts and bending metal into a u-brackets to go around the chain stays. You can buy pipe hangers at the hardware store to do the same thing,

 

[Zambam]

Heh - Mine's floppy summer shorts. Catching on the seat on dismount. Brought me to the ground a few times but at least I was stopped. I try to stick to padded riding shorts to avoid the problem.

Happened to me a few times (jacket caught on tail of seat) dismounting while coming to a stop. My bike is light (41 lbs) so I was able to lean to my left stick my left foot out with a little hop w/o falling. Now I make sure to tighten the waist drawstring on my jacket so it does not hang over the seat/ get caught.

 

[Zambam]

That battery in a backpack? Kind of like carrying a gallon of milk on your back, isn't it?

There's all kinds of bike racks, I used to get these for $18, so I hate to pay more. It's sturdy though, and I adapted one to a rear swing arm on a suspension frame to carry 8 lb battery, It's just a matter of lengthening the front struts and bending metal into a u-brackets to go around the chain stays. You can buy pipe hangers at the hardware store to do the same thing,

How about some pics of that rack installed? I can't picture how your's is mounted from your description. I have the same rack but it's on a hardtail, not on a full suspension.

 

[E-HP]

That battery in a backpack? Kind of like carrying a gallon of milk on your back, isn't it?

There's all kinds of bike racks, I used to get these for $18, so I hate to pay more. It's sturdy though, and I adapted one to a rear swing arm on a suspension frame to carry 8 lb battery, It's just a matter of lengthening the front struts and bending metal into a u-brackets to go around the chain stays. You can buy pipe hangers at the hardware store to do the same thing,

I've found the weak point of that rack has been just above where the adjustable legs meet, causing the leg to snap after a few thousand miles.

I modified mine so the adjustable legs only supply vertical support, and added solid members to support the rear. It's super solid now,

My econo-e-bike

If it happens, and you reverse-pedal, does it stop? (that should, if it's PAS-triggered, and no throttle signal is present, "instantly" cease any PAS-caused throttle signal output). I'll need to check on that. For now, after re-reading the unofficial ES user guide, I made an adjustment to...

endless-sphere.com

 

[docw009]

I've found the weak point of that rack has been just above where the adjustable legs meet, causing the leg to snap after a few thousand miles.

I modified mine so the adjustable legs only supply vertical support, and added solid members to support the rear. It's super solid now,

My econo-e-bike

If it happens, and you reverse-pedal, does it stop? (that should, if it's PAS-triggered, and no throttle signal is present, "instantly" cease any PAS-caused throttle signal output). I'll need to check on that. For now, after re-reading the unofficial ES user guide, I made an adjustment to...

endless-sphere.com

Good fix!

On mine, the leg goes almost vertical, so less side stress on it, but we're all shade tree mechanics. Mileage varies.

 

[Zambam]

I've found the weak point of that rack has been just above where the adjustable legs meet, causing the leg to snap after a few thousand miles.

I modified mine so the adjustable legs only supply vertical support, and added solid members to support the rear. It's super solid now,

My econo-e-bike

If it happens, and you reverse-pedal, does it stop? (that should, if it's PAS-triggered, and no throttle signal is present, "instantly" cease any PAS-caused throttle signal output). I'll need to check on that. For now, after re-reading the unofficial ES user guide, I made an adjustment to...

endless-sphere.com

I don't think your bike has rear suspension? That makes mounting a rear rack much more challenging since the rear wheel has to go up and down.

 

[99t4]

The dropout is that the same as a torque arm? I have 2 of them also in transit.

No, the dropout is the slot at the bottom of the fork that the front axle slides into.

How does the fork fail? The motor will likely put out less than 1000w with 36v

Looks like your front suspension fork has aluminum lower legs, aluminum dropouts. The aluminum is much weaker, often not strong enough to overcome the forces of the hubmotor axle that wants to violently spin in the opposite direction to the wheel. The aluminum dropout can break apart and the front wheel comes off the bike causing a catastrophic crash. This is a real risk.

If you want to lessen the risk of losing the front wheel due to dropout failure, front Torque Arms (that fully capture the axle securely to the fork arms) are mandatory. That way, if the dropouts break, at least the TAs are still holding the wheel somewhat in place.

Here is a good example (note this is a non-suspension fork):

 

[Zambam]

I saw this full suspension bike with a cobbled together rear rack today and snapped this pic. Looks like 2 strips of thin sheet metal (each folded to make it stronger?) connect the rack to the seat post. The strips looks quite long and flexible which allow it to bend as the rear suspension goes up and down. How well do you think this works and how long before the sheet metal crack due to fatigue?

 

[aae34]

I saw this full suspension bike with a cobbled together rear rack today and snapped this pic. Looks like 2 strips of thin sheet metal (each folded to make it stronger?) connect the rack to the seat post. The strips looks quite long and flexible which allow it to bend as the rear suspension goes up and down. How well do you think this works and how long before the sheet metal crack due to fatigue?

View attachment 362732

You could say it has virtually no rear suspension available downward if you look closely enough.
Guessing it's touching solid w/rider on.

 

[e-beach]

The dropout is that the same as a torque arm? I have 2 of them also in transit.

The dropout is where the wheel axle seats. The axle seats in between the two prongs of the dropouts. The torque arms are the added parts that you will need to connect to the fork and wheel axle so in the event that your fork dropouts crack open you don't loose your front wheel and fly off your bike and on to your face.

BTW, my first build was my front wheel e-bike. I thought it would be simpler then a rear wheeled build. I was mistaken.

Ok, here is something you might be interested in.

Catastrophic Fork Dropout Crack - Torque Arm Saves the Day

I don't understand why my e-bike keeps cracking up,... literately. First the frame, and now the fork. I started hearing a weird squeak a day or two ago, but and I wasn't sure what it was. Today I was talking to a local street musician who has a front hub motor on a bike that tows his big trailer...

endless-sphere.com

Catastrophic Fork Dropout Crack - Torque Arm Saves the Day

I don't understand why my e-bike keeps cracking up,... literately. First the frame, and now the fork. I started hearing a weird squeak a day or two ago, but and I wasn't sure what it was. Today I was talking to a local street musician who has a front hub motor on a bike that tows his big trailer...

endless-sphere.com

 

[s-petersen]

At this point, just go for it. Check your dropout (fork tips) with a magnet. If it's steel you're ahead (your bike is supposed to have a steel frame, not sure if the forks are the same). Don't bother with PAS, use throttle in parallel with pedaling. PAS sucks it's so unpredictable, will get you into trouble sooner or later.

Your $26 battery is a good deal, 16" x 5.5" x 3" 9 lbs it's going to be difficult to mount it anywhere on your bike. Maybe put it into a back pack and see how it rides then find a smaller battery that fits the bike later?

Edit: I hope your kit has the motor laced to a rim already.

Yes it is already laced, it is supposed to be here tomorrow and includes the tire also. With shipping the battery was around $50, The built in BMS does work for charging, but not for discharging, because the BMS requires communication to turn the output on, some say connecting pin 2&3 turns it on, as long as there is current draw, but I am not sure.

 

[s-petersen]

You could say it has virtually no rear suspension available downward if you look closely enough.
Guessing it's touching solid w/rider on.
View attachment 362733

That's some damage, I hope they weren't hurt

No, the dropout is the slot at the bottom of the fork that the front axle slides into.


Looks like your front suspension fork has aluminum lower legs, aluminum dropouts. The aluminum is much weaker, often not strong enough to overcome the forces of the hubmotor axle that wants to violently spin in the opposite direction to the wheel. The aluminum dropout can break apart and the front wheel comes off the bike causing a catastrophic crash. This is a real risk.

If you want to lessen the risk of losing the front wheel due to dropout failure, front Torque Arms (that fully capture the axle securely to the fork arms) are mandatory. That way, if the dropouts break, at least the TAs are still holding the wheel somewhat in place.

Here is a good example (note this is a non-suspension fork):

That steel fork setup looks awesome! I don't think the rack would last long with bending constantly. I will figure this out and see what happens, I have most of the winter to figure it out, and show the progress.

 

[s-petersen]

I am messing up a little, sometimes i responded to the wrong post, because I missed where the post ended

 

[Zambam]

Yes it is already laced, it is supposed to be here tomorrow and includes the tire also. With shipping the battery was around $50, The built in BMS does work for charging, but not for discharging, because the BMS requires communication to turn the output on, some say connecting pin 2&3 turns it on, as long as there is current draw, but I am not sure.

$130 for 1000 W front hub motor laced to a rim + tire? Is the controller included? How about a link? Maybe I'll buy one.

Those used A123 ANR26659M1B cells are amazing if you happen to get a good pack. I run 2 of these A123 LFP 36V 20Ah 720Wh High Current Battery Modules with 96 Cells | Greentec Auto in series as 22S on my 1500 watt scooter, w/o BMS. All 22 cell groups stay balanced within 5 mv after charge and discharge (I check it after every charge and discharge cycle). I have around 250 miles on it so far. It runs much faster than the lead acid battery that originally came with the scooter. The 2 packs are too big physically so it's a temporary measure till I build a battery that fits in the battery space of the scooter.

 

[s-petersen]

It was a customer returned, guaranteed unit from Voilamart I offered $130, they accepted.

USED Voilamart 48V 1kW LCD 26in Ebike 100mm Front Hub Motor Wheel Conversion Kit | eBay

Voilamart 26" Electric Bicycle Conversion Kit 1500W Rear Wheel Motor E-Bike 48V. Voilamart Rear Fat Beach Tire Electric Bicycle E-Bike Motor Conversion Kit 1500W. Voilamart 26" Rear Wheel Electric Bicycle LCD E-Bike Motor Conversion Kit 1500W.

www.ebay.com

Nice deal on your packs as well!

 

[Zambam]

It was a customer returned, guaranteed unit from Voilamart I offered $130, they accepted.

USED Voilamart 48V 1kW LCD 26in Ebike 100mm Front Hub Motor Wheel Conversion Kit | eBay

Voilamart 26" Electric Bicycle Conversion Kit 1500W Rear Wheel Motor E-Bike 48V. Voilamart Rear Fat Beach Tire Electric Bicycle E-Bike Motor Conversion Kit 1500W. Voilamart 26" Rear Wheel Electric Bicycle LCD E-Bike Motor Conversion Kit 1500W.

www.ebay.com

Sold out. I don't really need another ebike or project so it's good it's sold out. Good luck on your's.

 

[gromike]

There are seat post racks, if you got enough post:


The A123 36v battery that you have is a great battery, outside of being big and heavy. I did finally get around to building a 12s3p out of them to fit in the limited space in my frame. I lost interest in this bike because a 36v TSD just ain't doin' it for me.




You have all the pieces (or at least most of them), and you have been schooled in the hazards. You might as well build it and see how it goes.

 

[s-petersen]

I'll have all of the major pieces tomorrow I'm mostly interested in making sure everything works so I can get any warranty issues addressed before spring. It does not have to be finished, just basically tested.
The post rack will raise the seat, so I would have trouble with getting on and off I think.

 

[Chalo]

I don't think your bike has rear suspension? That makes mounting a rear rack much more challenging since the rear wheel has to go up and down.

Dogman Dan modded seatpost racks to carry serious weight by attaching struts that reach forward to the frame.

Steel seatpost racks

 

[gromike]

... so I would have trouble with getting on and off I think.

Welcome to our world.
There are strategies for getting on a ebike. Stand one foot on a pedal, hit the throttle and swing the other leg over. Or lean the bike way over and step over the top tube.
Getting off of them ain't no problem, though it can be quite awkward, sometimes hilarious.
Or buy a step thru.