Cracked frame from riding excessively?

I’m guessing to much stress in at area have you been jumping it or any downhill runs on it because it looks like a simple commuter A to B bike and won’t handle anything like at and also just looks like a poor design and weak from the start I’m sorry to say but if you can’t get it replaced your out 3k if it really cost ya at much you got ripped off big time

Sorry to say, but a lot of these motorbike-ish eBikes are really cheap and prone to breaking like this.

And that is not steel, that’s aluminum. One can tell from the welds.

(Another way you can tell it’s cheap is that cable/hose that goes through the gusset. A hose should NEVER be against a bare metal edge like that. That’s a sign of very poor design because it’ll result in rubbing and failure.)

That’s toast, definitely should be warranty if you haven’t crashed or done anything cray cray, get naming and shaming, 1 star reviewing, make a big stink. I wouldnt trust the rest of the frame even if you did repair this one spot…

This should be a warranty issue. Name and shame the manufacturer everywhere until they decide to fix this.

Looks like they joined the top tube and the down tube very close together at the steer tube. That would lessen the rigidity of the fork and cause a lever effect against the down tube. I’m guessing they also ran into that issue hence the added gusset. Obviously it wasn’t enough to fix that design problem.

That weld bead running down the length of the DT from the HT created a mechanical stress riser (not to mention weakening the DT from heat deformation). It’s no accident that the tube cracked exactly at the point where the weld bead ends. That weld didn’t strengthen (gusset) the HT/DT joint, it massively weakened the DT.

FYI, that’s definitely aluminum, not steel. Aluminum is lighter, but also more brittle.

The end of those plates has created a stress point on the frame. It should be reinforced there, but obviously wasn’t reinforced enough.

So bad design is likely partly responsible here.

But bikes also have their limits. If you were riding beyond the intended use (down stairs, over curbs, on trails), or if you ever ran into something like a wall or the back of a car, you very likely started the crack which then propagated (grew) over time.

And if the manufacturer decides to claim it was impact / abuse damage, there’s not really much you can do to prove them wrong.

(And to add to what others have said, many ebikes are basically cheap junk. Expensive cheap junk. But not well designed, not really repairable, low customer service from the manufacturer. Consider buying your next one from a reputable brand like [the Specialized Globe](https://www.specialized.com/us/en/shop/bikes/electric-bikes/electric-hybrid-bikes/globe).)

That gusset design doesn’t look right. I am not a structural/mechanical engineer, but something looks off in terms of stress/strain on the frame. I think sometimes members can be too stiff and transfer excessive flexing elsewhere like where the crack is just under the gusset.

Can we get a picture of a whole bike? i’m really interested if this costs 3k$

That’s not steel its aluminium. Unless you pay a stupid amount for an ebike they often have really poor quality frames that are not up to much more than smooth roads. Many people assume that because it looks like a mountain bike it’s for offroad which isn’t the truth.

You have a triple clamp fork which puts a lot more strain through the headset. The frame has failed at the end of the gusset that’s there for extra strength. Can’t comment on if it should be dealt with under warranty or not many reputable manufacturers give amazing warranties on frames to the point its rare anything is refused but every ebike warranty that I have seen that wasn’t from one of the major manufacturers had so many rules and exceptions about what wasn’t covered in would be surprised if they had anything that was.

Chinesium strikes again. You got china crap scammed
Imagine such a weld on a reputable bike brand. They’d be out of business

Hard to say, but a crack like that on a down tube is likely from a head on collision, or bearing too much load for too long.

Coupled with a cheap bike design/manufacture. Aluminium frame isn’t the best choice of frame materials for an ebike anyway, really steel is the way to go, it’s stronger and flexes more than aluminum does.

There’s a good chance the gusset was welded in too hot further weakening the down tube (heat effected zone), but that’s difficult to prove without serious/expensive testing.

Traditionally bicycles used two parallel top tubes, not gussets, for greater load capabilities.

Don’t ride it, can’t really fix it, it’s done