My ebike frame cracked? Help!

Kagamoosha

Kagamoosha

1 W
Joined
Nov 25, 2013
Messages
55
Location
Baton Rouge, LA
I was riding my e-bike last week when all of the sudden the frame cracked right below the welding in the middle. All the components are fine, but the bike frame is ruined. I currently have a 20 in rear wheel hub motor and was wondering what my best plan of action would be for putting the batteries and hub motor on a new bike. I want to get a steel frame so this doesn't happen again, but I would like to switch to a bigger wheel if possible. Can someone help me decide what kind of bike would be inexpensive to put a rear hub motor on, but would be safe and not crack like the last one. Thanks!
 
You can get that fixed.
I'd split a section away, internally sleeve it and weld it back up. If you can't weld the alloy, take it to a local workshop
 
that looks really cheap
look at those cheapo pedals
How this rear shock is mounted is a joke.
What kind of speeds did you reach on your ebike before breakage??
 
Not sure what you have there, but if it's alloy I wouldn't try welding it. Steel, you could get it fixed. So you jump it, right?

In 26" wheels, you can't beat the steel frame MTB with no rear suspension. In FS, head for bikes that don't sell for $300. Once into used bikes that once sold for $1500, its mostly durable enough for most folks. But if you huck a lot, look for downhill frames.

There are exceptions, I have pounded the living hell out of a mongoose blackcomb that was a cheap bike. I did put forks worth more than the whole bike on it though. But the bikes frame is pretty hard to break. It's a bit floppy from side to side though.

The blackcomb may not be available anymore, but for a while it was super cheap at walmart online in the usa.

As usual, the guy needs to fill in his location so we know where on earth he is. Walmart USA won't help him if he's in Croatia. Speaking of Croatia, want a strong ebike frame? See Greyborg.
 
Pretty amazing damage, for normal use. I do suspect the wheels left the ground. Or he's a big boy.
 
Looks like the shock mount is in single shear? So probably been waggling that frame lug side-to-side with each loading cycle of the suspension, resulting it classic fatigue failure originating at the weld (as is often the case).
 
Right, that makes sense. Overload a bike and it wags it's tail. You can see cheap frames bend side to side like wet noodles with every pedal stroke.
 
Yeah so I'm dialing back down to 36 volts to make sure this doesn't happen again. But I need some suggestions for some good bikes made of steel that can have a rear motor attached. :mrgreen:
 
The cracks look white - is it steel or alu? Check with a magnet. Looks like low cycle fatigue.
Don't dismiss aluminium frames though, just ones with bad design at critical load/fatigue points!
 
Nope definitely not steel! I looked through some forums today and even went to Target but the bikes made of steel have a small area for the hub motor and I'm afraid that it would just break at the tail. I definitely don't want the motor to come off the back of the bike! Did the suspension play a part in the frame cracking, or was it just too much power for that type of material? I'm not sure if the rear suspension made the bike weaker because it was not welded together in one piece.



:?: I... I must seek Buddha. I must seek Christ"

Thurgood Jenkins: You must seek therapy.
 
You may be a bit reluctant to use another cheap bike, but this one is steel and looks very similar to the picture of yours:
http://www.amazon.com/Stowabike-Folding-Suspension-Mountain-Shimano/dp/B006JCUPJY/ref=sr_1_1?ie=UTF8&qid=1386383091&sr=8-1&keywords=Stowabike
Mine has about 2500 miles now. I removed the derailleurs, and welded on a torque plate/disc brake mount on the rear for avid bb7 brakes.
 
I definitely want to invest in a torque plate/disc brake mount for additional support, but I don't know where to find them on the internet. Any suggestions?
I think I'm gonna buy this Schwinn at Target today to see if the motor will fit that frame style.

http://www.target.com/p/schwinn-men-s-ranger-26-mountain-bike-red/-/A-13241029#prodSlot=large_1_14
 
I bought a schwinn from target for my very first ebike. It lasted 1000 miles, and then the frame was wiggeling like a wet noodle. no cracks, but it was unsafe to ride.

A good steel frame would be an older trek 800 series. They generaly had 7 speed rears and a steel frame. Craigslist is the best place for them.
Get the torque arm(s) from Ebikes.ca

As for your bike, those BSO (bike shaped objects) just aren't strong enough for even normal daily pedaling. Most of those cheapo folding frames have a listed maximum gross weight of 200-220lbs. Once you start adding more power to them in the form of a motor, and higher stress from more speed, they aren't going to survive long.
 
Seriously, more of the same junk isn't going to improve this situation.

Think about it - an eBike already weighs 3-4x times what it did before conversion. Of course, most of us are "large size" couch-surfers so that's probably another 40-50lbs over the average fit cyclist.

eBike's usually roll much faster and speed exhibits non-linear force on chassis. In other words, merely doubling speed may inflict 4-8x times stress on the chassis. It all "depends" of course but fact is there's more to eBikes than meets the eye or wallet.

Regardless if alloy or steel good quality bikes (Trek, Cannondale, etc.) always survive better than BSO garbage - Craig's list is where I find good platforms at box store price. Of course, only after enough due dilligence to weed out stolen property and other scams.

You've obviously been "bitten" so my advice is to save yourself the anguish of trying to keep trash up and running - invest in a quality bike to convert. Used, probably not more than $100-$200 difference and well worth all the work you will put into a good performing, reliable and long lasting eBike.
 
Because my first bike with a robust steel frame was stolen, I have gotten considerably more mileage out of my cheap folder.

Would someone kindly direct me to reports of cheap folding frame failures?
 
Since it's a 20" get a nice stout steel bmx bike, and bend out the rear fork enough to use the motor with a single speed freewheel.
 
I am 6 feet tall, so most of the BMX bikes I've sat on in Academy and Walmart are too small. I used a bike calculator and it said the frame would need to be at least 23 inches long for my body. Where do you suggest I find a suitable BMX bike?
Thanks for the help BTW!
 
I just took the motor off the bike, but the side I fell on was the side the phase wires come out of the motor and it was pretty scraped up. I don't think I should take the nut off all the way, because I might not be able to get it back on. What a nightmare! Also I'll have to buy a new throttle! That also got ruined in the wreck. But at least I'm healing and no major damage was done!

I paid $675.00 with free shipping for the e-bike.
I bought a Lyen controller at $125.00 + 3 way switch + USB adaptor
I bought a new battery $250.00
I bought front and rear lights from electricbike.com for $75
Total about $1200.00


As long as I don't spend over 300 dollars I think I should be fine. If I "HAVE" to spend over $300 I want the bike to be solid!

I would love to be able to create a battery and controller compartment in middle of the frame, but I am willing to sacrafice to having a rear battery rack.
 
Kagamoosha said:
So not just any Trek frame will do. It has to be vintage? Because I see a few on CL for around $300.00
Click to expand...
Well the 800 series is steel, most other Treks are Alloy. and older because a new 800 would break your budget.Also some of the newer modles used 8,9,10 speed rear sprockets, making the conversion more complicated and expensive. But a good bike like a trek, speaclized, Cannondale, ect, will last decades, not seasons like a department store bike.
 
Drunkskunk said:
Kagamoosha said:
So not just any Trek frame will do. It has to be vintage? Because I see a few on CL for around $300.00
Click to expand...
Well the 800 series is steel, most other Treks are Alloy. and older because a new 800 would break your budget.Also some of the newer modles used 8,9,10 speed rear sprockets, making the conversion more complicated and expensive. But a good bike like a trek, speaclized, Cannondale, ect, will last decades, not seasons like a department store bike.
Click to expand...
Trek 900 series are good choices too especially the older US built lugged steel ones which are great bikes all around. But any steel hardtail from the 90s to early 2000s will be fine and should be cheap used. I've picked up two Trek's, a 930, and a 950 both for under $100 each on Craigslist, in great condition except for needing a bit of cleaning.
 
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