Context: Bicycle wheels can become untrue if the rim is bent, e.g. from hitting a curb.
The usual question: Can a bent aluminium rim be bent back straight?
The two camps (figuratively):
1. Sure, go for it! See for instance: http://www.sheldonbrown.com/on-road-wheel-repairs.html
2. NEVER bend aliminium. See for instance some posts at: http://www.bikeforums.net/bicycle-mechanics/374083-pothole-damaged-rim-fix-replace.html
I have observed that many people hold an opinion in between. For instance Zinn in his book Zinn & the Art of Road Bike Maintenance claims that an aluminium rim can be bent as an emergency repair on the road (The Sheldon Brown link is also framed as conerning roadside repairs).
My question: Does bending an aluminium rim actually make it much more prone to failure?
I am well aware that the question can be interpreted in many ways and that it can produce low quality answers with anecdotal evidence. To prevent this, I will try to specify what kind of answers I do and do not seek:
- Please do not mention one single instance when you bent a rim straight, then your rode it a few times and it still remained intact.
- Please do not mention if your rim broke one, after bending it straight, as a result of an accident that could otherwise easily have bent it.
- Answers that refer to multiple, well monitored cases observed over a long time are premiered. For instance, if you have bent several rims straight for several friends over 20 years of time and you know that each of them have ridden the wheels for a long time and that they would report if something went bad.
- Please add details, such as how bent the rims were before you straightened them (approximate deflection from the straight wheel plane) and for how long and "how hard" the wheels have been ridden, if possible.
- As an exception to the above points, I would be interested in single cases that a rim has collapsed after being bent straight, after being used under normal, not exceptionally straining conditions. This is because I have never ONCE heard of this happening. And I have seen and read about quite a few bikes in my time.
Although the question still can lead to multi-faceted I think that it is highly relevant. I think of this often, but I have been unable to find solid evidence for one camp or the other. Either people claim that bending rims has worked for them on few occasions, or they claim that "aluminium must not be bent", as if that were a universal truth without room for exceptions.