Frame Snapped

[indianajo]

Thianks for listing the name of the perpetrator. US sold bikes risk a huge tort penalty for failures like this. My aluminum frame bike has 12000 miles with loads up to 240 lb. I bet Mukkpet US assets include a cell phone and a website on leased server space - ie nothing to liquidate if you win a lawsuit. Buy a major bike - Giant, Trek, Specialized, Gazelle, Cannondale, Kona . Or put up with junk like this.
In 1957 a Sears 20" bike fractured at the steering post weld, and stabbed me in the belly. No stitches were required. I weighed an enormous 40 lb, and did not jump curbs or picnic tables. Sears paid a welder to repair it.

 

[stompandgo]

Riding to work and suddently things got way too bouncy! About 6mo old. About 1500km on paved roads. Seems aluminium may not be a good choice for bike frames. Anyone else seeing this happen?

View attachment 193175

Just because welds are "pretty" doesn't make them strong. The bottom side of that weld is the highest stress point of the tube junction. It looks like that's exactly where it broke. Once there is any kind of movement in a welded joint, no matter what the material, it will fail. In this case, it looks like the tubing failed after the weld broke and allowed movement in the joint.

The better aluminum framed e-bikes use hydroformed aluminum sheet, not tubing, in the high stress areas.

 

[Chazmo]

So, @Curtech , it looks like you have a 1yr warrantee.

I agree with what these guys said about the tubing looking not “beefy” enough for a typical aluminum frame. Anyway, good luck with your claim!

 

[Catalyzt]

All very interesting. Early versions of the Marin Team 1 sometimes experienced broken seat stays, though everyone seems to love Marin and says they are super reliable.

They repaired the broken frames at no charge and redesigned the frame / welds at least twice before my version, but I trolled through a lot of posts before pulling the trigger. No one who had a cracked Team 1 frame was injured or even had an accident, at least in the posts that I found.

Jabber and Stomp understand the metallurgy way better than I do, but sometimes thick frame tubes sometimes crack, too. I think it was Orbea-- or some other medium-sized brand-- that had multiple failures in the same model eBike. Again, no injuries among the many angry customers-- I think that as a down tube.

It is amazing that aluminum-- or steel-- frames breaking seems to rarely cause catastrophic failures. My worst experience with this was actually on a 1950s Raleigh three speed women's bike that was the family beater during the 1970s. (I would NEVER leave the Raleigh Competition chained to anything in anywhere public. Even overnight in the basement of a friend's apartment, it got locked.)

Anyway, riding home from school one day-- on the Central Park 79th Street Transverse-- I noticed the bike was handling a little differently, and power delivery seemed to be degrading. Then an odd rocking motion. Then a weird scraping sound. Then the handlebars moved closer to me.

Then I pulled over and saw that the down tubes had cracked. The top one was hanging by a thread, the bottom one had separated completely. and the BB was dragging on the pavement. What was holding the bike together was basically just my hands holding the handlebars. When I looked more closely, the culprit was clear: Rust. "Gee, I guess I should have examined it more closely."

I still ride the 1974 Competition in NYC. I wonder if there is a way to have the frame checked. It has been in one bad accident, and another very, very bad accident, where I flipped it going 30 MPH.

Sometimes it seems like a miracle I've survived to my late 60s.

 

[Curtech]

Sure. Here's a few.