appa609

Hey everyone.
I was biking a little while back and visited my friend's house, where we decided to have a quarter-mile sprint race, just for fun. I had a 4 year old aluminum frame mountain bike that had never been in an accident. I shifted to a low gear for the start, but a few strokes in, my hanger sheared off and my rear derailleur flew straight into my spokes. Back wheel locked up, and I almost slid into the curb. I ended up breaking 2 spokes, damaging 3 or 4 more, and annihilating my derailleur.

I'm not sure how much this happens, but a good friend of mine has also had the same problem, and I've seen lots of pictures of the same happening on the internet. I ended up spending half nearly half the price of my bike on repairs.

I know that hangers are designed to shear off to protect the frame and derailluer from damage, but it seems that after it does, it's moving with substantial freedom and it has a fairly good chance of getting caught in the rear wheel and getting ripped apart. I decided to tackle this problem for an engineering class, and I thought perhaps one could incorporate some sort of integrated retaining mechanism into the hanger construction so that when it experienced too much load and sheared, the derailleur could be kept in place and prevented from damaging the rest of the bike and itself.

I have some ideas in mind for the specific mechanisms, but since you're all much more experienced at bike maintenance than I am, I was wondering if any of you had any suggestions.

Also, we need to collect survey data for the class, so I'd really appreciate it if all you were to complete a short online form I've prepared.
[admin edit]
Thank you!

AnkleWork

You probably reversed that: your rear derailleur contacted the spokes and your hanger broke off as a result.

The real question is why did the RD move into the spokes?

Siu Blue Wind

Please post your survey in the survey/feedback forum with the following criteria.


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