Building a Powerful Ebike

General Discussion about electric bicycles.
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MadRhino   100 GW

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Re: Building a Powerful Ebike

Post by MadRhino » Jan 06 2019 9:28am

tolkaNo wrote:
Jan 06 2019 8:38am
Build a giant dh comp/team
The GT DHI that the OP has found is a better frame. A bit more work to build than a Giant, but well worth it.
Make it fool-proof, and I will make a better fool.
Current bikes
Street: https://s20.postimg.org/ewrvugywt/Session_04_2015.jpg
Dirt: https://s20.postimg.org/lbqwr55ml/IMG_0157.jpg

tolkaNo   100 W

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Re: Building a Powerful Ebike

Post by tolkaNo » Jan 06 2019 9:37am

MadRhino wrote:
Jan 06 2019 9:28am
tolkaNo wrote:
Jan 06 2019 8:38am
Build a giant dh comp/team
The GT DHI that the OP has found is a better frame. A bit more work to build than a Giant, but well worth it.
Why is the GT a better frame?

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MadRhino   100 GW

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Re: Building a Powerful Ebike

Post by MadRhino » Jan 06 2019 7:11pm

tolkaNo wrote:
Jan 06 2019 9:37am
Why is the GT a better frame?
The DHI is made much stronger, with better lateral stiffness. Much better suspension design, that is able to tune the rebound of a heavy hub.

The Giant DH comp had been popular on ES because it is one of the very few DH frames that has room for batteries inside the front triangle. Also, most of them were sold cheap on the used market, making it an interesting donnor bike.
Make it fool-proof, and I will make a better fool.
Current bikes
Street: https://s20.postimg.org/ewrvugywt/Session_04_2015.jpg
Dirt: https://s20.postimg.org/lbqwr55ml/IMG_0157.jpg

Amiran   10 W

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Re: Building a Powerful Ebike

Post by Amiran » Jan 08 2019 4:16pm

Callbrin wrote:
Jan 03 2019 3:02am
I am planing to build a powerful ebike [my 2nd one] but I not sure what I need.

First I'm either gonna need a fat bike or a regular bike with 150mm dropout for obvious reasons but I'm not sure what to get as I dont want any of those frames that look like dirt bikes like the grey borg or stealth bomber.

List of Bikes For possible use:

https://www.amazon.com/Huffy-Mens-Fortr ... op?ie=UTF8 [already have andf it is 155mm rear dropout but is a cheap walmart bike]

https://www.amazon.com/Firmstrong-Delux ... X0DER&th=1 [Rear Dropout width is unknown but its made of steel so I might be able to stretch it]

https://www.ebay.com/itm/Schwinn-Stingr ... rk:10:pf:0 [Looks cool but unsure if its worth it to get this]


List of Possible Kits

https://ncyclebike.en.made-in-china.com ... r-Kit.html [8000w]

https://www.aliexpress.com/item/48v-72v ... 266fbaab20 [5000w]

https://www.amazon.com/theebikemotor-30 ... B01GSR8MLW [3000w Has option for fat wheel]

Now The Problems:

Rear dropout width

battery size [thinking maybe running 96v instead of 72v]

Trusted kits [I want a lot of torque but I dont want to overspend. Do I even need 5kw? The torque is rated at 190nm and around 65mph so the 5kw looks best bust the battery sizing is and issue then.

Possible Batteries For Diy Battery

https://www.imrbatteries.com/samsung-30 ... p-battery/ [3000mah 5C]

https://www.imrbatteries.com/samsung-50 ... a-battery/ [21700 Cell, 5000mah 1.95C]

https://www.imrbatteries.com/lg-mh1-186 ... p-battery/ [3200mah 3.125C]

I dont want a lot of voltage sag but I want the batteries to not struggle giving full power and then some to the motor
Boss,do not buy from Ncyclebike. They are resellers.
If you buy in China you can deal with manufacturer. I suggest QS.

markz   100 GW

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Re: Building a Powerful Ebike

Post by markz » Jan 08 2019 5:55pm

Dude, just dont go 65mph on a fuckking bicycle man, just dont. Just because others do it, dont follow suit. Bicycles are not meant for that kind of fibration or stress. Might as well just buy a motorcycle frame and put some fake pedals on it. I doubt even them motorcycle looking ebike frames are capable of hitting a pothole on a road at 65mph.

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MadRhino   100 GW

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Re: Building a Powerful Ebike

Post by MadRhino » Jan 08 2019 9:37pm

markz wrote:
Jan 08 2019 5:55pm
Dude, just dont go 65mph on a fuckking bicycle man, just dont. Just because others do it, dont follow suit. Bicycles are not meant for that kind of fibration or stress. Might as well just buy a motorcycle frame and put some fake pedals on it. I doubt even them motorcycle looking ebike frames are capable of hitting a pothole on a road at 65mph.
Good DH frames are made to ride that speed, down wild mountain trails. Don’t worry, the bike is capable. The rider is the only concern.

Make it fool-proof, and I will make a better fool.
Current bikes
Street: https://s20.postimg.org/ewrvugywt/Session_04_2015.jpg
Dirt: https://s20.postimg.org/lbqwr55ml/IMG_0157.jpg

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Chalo   100 GW

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Re: Building a Powerful Ebike

Post by Chalo » Jan 09 2019 1:57am

MadRhino wrote:
Jan 08 2019 9:37pm
Good DH frames are made to ride that speed, down wild mountain trails. Don’t worry, the bike is capable. The rider is the only concern.
Those are short events. And racers who reach such speeds don't keep running the same bike season after season. Maybe the bikes can tolerate routine motorcycle-like use, and maybe not. Their intended purpose is different.
This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

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Re: Building a Powerful Ebike

Post by MadRhino » Jan 09 2019 3:15am

Chalo wrote:
Jan 09 2019 1:57am
MadRhino wrote:
Jan 08 2019 9:37pm
Good DH frames are made to ride that speed, down wild mountain trails. Don’t worry, the bike is capable. The rider is the only concern.
Those are short events. And racers who reach such speeds don't keep running the same bike season after season. Maybe the bikes can tolerate routine motorcycle-like use, and maybe not. Their intended purpose is different.
Well, my Santacruz V10 Mk1 that is a 2004 that I have bought new with lifetime crash guarantee (that is not unusual for top DH racing frames). It had suffered a few dozen hard crashes before I built it as an ebike, and another dozen at least since then. I have watched it once, bucking down a 70ft rocky cliff bumping a few maple trees on the way. It is still as new, not the paint of course but perfectly straight and no cracks. Many DH frames were made as strong as a V10. It is not the first that I have beat in the mountain. As a dirt motorcycle rider, I can testify that many off road MC can’t suffer the beating that DH bikes are surviving, nor can they make as good a ride in mountain trails.

Choosing a good DH frame, building and tuning it it properly, can make an ebike that is safe to ride very fast. On the street, those very stiff overbuilt frames with high end suspension components, are on a leisure trip. I can leave the handlebar of my Trek Session 10 commuter and let it coast from 50 Mph to a stop, not even blinking for a pothole. At its 65 Mph top speed, I feel it would still be a good ride at double that speed.

People who never did ride a top DH racing bike, have no idea how good a ride they are, and how much beating they can take.
Make it fool-proof, and I will make a better fool.
Current bikes
Street: https://s20.postimg.org/ewrvugywt/Session_04_2015.jpg
Dirt: https://s20.postimg.org/lbqwr55ml/IMG_0157.jpg

n3glv   10 mW

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Re: Building a Powerful Ebike

Post by n3glv » Jan 09 2019 6:04am

Whatever you do, get the thickest spokes you can, or use moped wheels.
BC eventually at some point you'll rip the spokes out of the rim.. Cheers.

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MadRhino   100 GW

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Re: Building a Powerful Ebike

Post by MadRhino » Jan 09 2019 7:39am

n3glv wrote:
Jan 09 2019 6:04am
Whatever you do, get the thickest spokes you can, or use moped wheels.
BC eventually at some point you'll rip the spokes out of the rim.. Cheers.
Thin spokes and rim washers are doing much better.

Big spokes need heavy rims, heavy rims need heavy tires, heavy wheels need heavy suspension, heavy bikes need motorcycle brakes, etc... starts with a spoke, ends with a 100 lbs battery.
Make it fool-proof, and I will make a better fool.
Current bikes
Street: https://s20.postimg.org/ewrvugywt/Session_04_2015.jpg
Dirt: https://s20.postimg.org/lbqwr55ml/IMG_0157.jpg

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Chalo   100 GW

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Re: Building a Powerful Ebike

Post by Chalo » Jan 09 2019 12:02pm

n3glv wrote:
Jan 09 2019 6:04am
Whatever you do, get the thickest spokes you can, or use moped wheels.
BC eventually at some point you'll rip the spokes out of the rim.. Cheers.
The spokes that damage a rim soonest and most often are the thick ones, because they lack elasticity and require higher tension to stay tight. For 6-passenger pedicabs that can pack more than 2000 pounds gross weight, what has proven to work best is big heavy wide rims laced with 14/15ga butted spokes.

On the other hand, normal bicycle rims laced with 12ga spokes routinely suffer cracks at the rim holes-- if they're done up tight enough that they don't unscrew themselves in normal use.

I've said it before and I'll surely have to say it again: the strength of the wheel is in the rim. Spokes' job is to support the rim without going slack, and to do that job they need elasticity.

If you double the spokes' cross-sectional area, you have to double the tension to get equal reliability. Rims can only take so much tension before they suffer problems. To get thick heavy motorcycle spokes into their proper tension range, you need a thick heavy motorcycle rim, which takes a thick heavy motorcycle tire.

To be fair, the OP intends for this bike to do a motorcycle's job, so that might not be a bad idea. But motorcycle wheels should attach to a motorcycle, not a bicycle.
This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

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Re: Building a Powerful Ebike

Post by billvon » Jan 09 2019 6:18pm

MadRhino wrote:
Jan 08 2019 9:37pm
Good DH frames are made to ride that speed, down wild mountain trails.
Absolutely - with a live load (a ~180lb rider using his legs as part of his suspension) they do very well. Taking those impacts with ~100lbs of dead weight affixed rigidly to the frame (i.e. a battery, controller, motor) is a whole different story.
--bill von

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Re: Building a Powerful Ebike

Post by MadRhino » Jan 09 2019 8:24pm

billvon wrote:
Jan 09 2019 6:18pm
MadRhino wrote:
Jan 08 2019 9:37pm
Good DH frames are made to ride that speed, down wild mountain trails.
Absolutely - with a live load (a ~180lb rider using his legs as part of his suspension) they do very well. Taking those impacts with ~100lbs of dead weight affixed rigidly to the frame (i.e. a battery, controller, motor) is a whole different story.
First, dead weight added to the bike doesn’t need to be 100 lbs. I do it with 50 lbs max, even less with short range lipo pack.

Second, many DH riders are 200+ lbs big guys. A 165 lbs rider plus build weight does match, and the old school DH bikes that we are building on, are overbuilt frames.

Third, we don’t ride ebikes in the worst trails out there, neither are we taking big drops. Even the best of us are riding steep descents pretty conservatively. It is climbing and nice sections, that are letting us freedom of power and speed.

Then, when we build a street commuter, the roughest terrain that it will ride can’t be much worse than potholes and speed bumps.
Make it fool-proof, and I will make a better fool.
Current bikes
Street: https://s20.postimg.org/ewrvugywt/Session_04_2015.jpg
Dirt: https://s20.postimg.org/lbqwr55ml/IMG_0157.jpg

markz   100 GW

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Re: Building a Powerful Ebike

Post by markz » Jan 09 2019 8:54pm

MadRhino wrote:
Jan 08 2019 9:37pm
Good DH frames are made to ride that speed, down wild mountain trails. Don’t worry, the bike is capable. The rider is the only concern.
I know what you mean, but its his/hers first ebike, I think, too lazy to scroll and read.

billvon   100 MW

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Re: Building a Powerful Ebike

Post by billvon » Jan 10 2019 12:01pm

MadRhino wrote:
Jan 09 2019 8:24pm
First, dead weight added to the bike doesn’t need to be 100 lbs. I do it with 50 lbs max, even less with short range lipo pack.
Agreed - but if the goal is "a powerful ebike" you're going to be tending towards heavier batteries. (And he said he wants a large battery.)
Second, many DH riders are 200+ lbs big guys. A 165 lbs rider plus build weight does match, and the old school DH bikes that we are building on, are overbuilt frames.
Right. But DH riders don't plant their butts on the seats when they are going downhill. They are on their pedals, using their legs to absorb much of the impact. That greatly reduces the loads that the frame sees, and puts the load where the bike is designed to handle it (the bottom bracket.)

Now compare that to a battery. Most are completely dead loads, without any suspension internally. If you see a 10G bump on a 50lb battery, that means 500 lbs on a part of the frame that was NOT designed to handle that load. With the design margins built into a DH frame you are usually OK. But it's not just like bombing down a steep trail with a heavy rider.
--bill von

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MadRhino   100 GW

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Re: Building a Powerful Ebike

Post by MadRhino » Jan 10 2019 2:37pm

billvon wrote:
Jan 10 2019 12:01pm
MadRhino wrote:
Jan 09 2019 8:24pm
First, dead weight added to the bike doesn’t need to be 100 lbs. I do it with 50 lbs max, even less with short range lipo pack.
Agreed - but if the goal is "a powerful ebike" you're going to be tending towards heavier batteries. (And he said he wants a large battery.)
Second, many DH riders are 200+ lbs big guys. A 165 lbs rider plus build weight does match, and the old school DH bikes that we are building on, are overbuilt frames.
Right. But DH riders don't plant their butts on the seats when they are going downhill. They are on their pedals, using their legs to absorb much of the impact. That greatly reduces the loads that the frame sees, and puts the load where the bike is designed to handle it (the bottom bracket.)

Now compare that to a battery. Most are completely dead loads, without any suspension internally. If you see a 10G bump on a 50lb battery, that means 500 lbs on a part of the frame that was NOT designed to handle that load. With the design margins built into a DH frame you are usually OK. But it's not just like bombing down a steep trail with a heavy rider.
Powerful ebikes riders are using RC Lipo, no one with a brain would build a fast dirt bike on a bicycle frame with 50 lbs of batteries. I never use more than 21 lbs. My dirt bike with 1.3 kw/h battery is 82 lbs. Its geometry, suspension and brakes are upgraded/ tuned for the riding weight.

Only idiots would ride downhill on their butt. That is a sure way to hospital.

Then, you are the only one to know what YOU can or can’t build and ride good. So am I.
Make it fool-proof, and I will make a better fool.
Current bikes
Street: https://s20.postimg.org/ewrvugywt/Session_04_2015.jpg
Dirt: https://s20.postimg.org/lbqwr55ml/IMG_0157.jpg

Callbrin   10 mW

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Re: Building a Powerful Ebike

Post by Callbrin » Jan 11 2019 3:09am

OK wow its been a few days and i see this has gotten some attention. So after some thought and ready the replies I think I might not go with the 3kw kit on a normal bike as what other replies have said with the problems it would have. This was going to be my 2nd ebike but I figure I would rather upgrade the battery instead on my first and the brakes as well. Currently its a 1500w voilamart kit from eBay with a 52v 20ah battery. and going probably around 25-28mph on it I get around 10miles [20%-80%] so i would say on a full charge around 18miles.


My plan was to increase the battery capacity to around 30-35ah and I wanted to use the same cells I am using now [Samsung 25r].
I would build a frame case for the center to even out weight distribution and more room but IDK the best way to go about this so...

1. whats the best way to attach the box frame to the bike frame for my batteries
2. I wanted to save money by buying more 25r's but is it worth it?
3.is there any heating problems I should worry about for the motor since @ 35ah it the battery would be @ 1820wh
4. The controller get pretty warm, bag [no airflow] so it would defiantly over heat from this so should I get something like the 60amp controller from lunacycle?

also thanks to everyone who replied for the info and help

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Chalo   100 GW

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Re: Building a Powerful Ebike

Post by Chalo » Jan 11 2019 10:56am

Callbrin wrote:
Jan 11 2019 3:09am
This was going to be my 2nd ebike but I figure I would rather upgrade the battery instead on my first and the brakes as well. Currently its a 1500w voilamart kit from eBay with a 52v 20ah battery.
[...]
My plan was to increase the battery capacity to around 30-35ah and I wanted to use the same cells I am using now [Samsung 25r].
Mixing used and new cells in the same pack is not a great idea, because it invites imbalance problems. It's probably better to add a second complete pack in parallel, taking care to connect them together only when they are at the same voltage (e.g. fully charged).
This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

2old   100 kW

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Re: Building a Powerful Ebike

Post by 2old » Jan 11 2019 11:48am

The kit info states it's capable of 34 mph @ 48V, but is restricted to 24 for street use, and should be capable of more @ 52V especially with the cells you're using. Have you removed the restriction in which case they're information is faulty? I ask because my YESCOM kit goes 33+ mph with a 30 amp controller @ 52V (I realize the motors could be wound differently).

larsb   10 kW

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Re: Building a Powerful Ebike

Post by larsb » Jan 12 2019 3:21pm

I come from retiring an old Kona stinky downhill built to ebike, capable of 65mph - i can say it's certainly strong enough and capable of doing those speeds. I did 10000miles commuting on it. Geometry always felt a bit off though so i'd not pick that particular frame for a build.

I'd buy motor/controller from QS motor, they are an ok manufacturer/seller. Don't go for the no name cheap kits. It'll bite you in the ass!
Ride on :D

2old   100 kW

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Re: Building a Powerful Ebike

Post by 2old » Jan 12 2019 6:09pm

You wouldn't glean that from the posts that I've seen where users are getting 20,000+ miles from their no-name kits. Mine has performed perfectly for three + years.

larsb   10 kW

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Re: Building a Powerful Ebike

Post by larsb » Jan 13 2019 2:21am

Quality isn't a handful of user stories. It's when you can produce with 1/1000 or even 1ppm faults.

So quality never shows here.

From the same reasoning i cannot say that QS has perfect record. I know they are not bad in quality or to deal with. They don't use the shittiest materials, they have some customer support. And they aren't expensive - so i'd recommend them instead of unknown sellers. Cheers.
Last edited by larsb on Jan 13 2019 4:42am, edited 1 time in total.
Ride on :D

brone   1 mW

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Re: Building a Powerful Ebike

Post by brone » Jan 13 2019 3:56am

Callbrin wrote:
Jan 11 2019 3:09am
OK wow its been a few days and i see this has gotten some attention. So after some thought and ready the replies I think I might not go with the 3kw kit on a normal bike as what other replies have said with the problems it would have. This was going to be my 2nd ebike but I figure I would rather upgrade the battery instead on my first and the brakes as well. Currently its a 1500w voilamart kit from eBay with a 52v 20ah battery. and going probably around 25-28mph on it I get around 10miles [20%-80%] so i would say on a full charge around 18miles.


My plan was to increase the battery capacity to around 30-35ah and I wanted to use the same cells I am using now [Samsung 25r].
I would build a frame case for the center to even out weight distribution and more room but IDK the best way to go about this so...

1. whats the best way to attach the box frame to the bike frame for my batteries
2. I wanted to save money by buying more 25r's but is it worth it?
3.is there any heating problems I should worry about for the motor since @ 35ah it the battery would be @ 1820wh
4. The controller get pretty warm, bag [no airflow] so it would defiantly over heat from this so should I get something like the 60amp controller from lunacycle?

also thanks to everyone who replied for the info and help
Lol 18miles on a 20Ah battery? That battery is definitely not 20Ah

Callbrin   10 mW

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Re: Building a Powerful Ebike

Post by Callbrin » Jan 16 2019 11:47pm

2old wrote:
Jan 11 2019 11:48am
The kit info states it's capable of 34 mph @ 48V, but is restricted to 24 for street use, and should be capable of more @ 52V especially with the cells you're using. Have you removed the restriction in which case they're information is faulty? I ask because my YESCOM kit goes 33+ mph with a 30 amp controller @ 52V (I realize the motors could be wound differently).
I think its mainly because I weight 270lbs but other than that it is a generic one from china so it could be over stated

Callbrin   10 mW

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Re: Building a Powerful Ebike

Post by Callbrin » Jan 16 2019 11:48pm

brone wrote:
Jan 13 2019 3:56am

Lol 18miles on a 20Ah battery? That battery is definitely not 20Ah
I thinks the motor just isn't efficient or that I weight a lot and the bike with everything on it also weighs around 80lbs and I blast full speed all the time
Last edited by Callbrin on Jan 18 2019 2:31pm, edited 1 time in total.

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