Cyclemark

There are many posts about frame failure. For those inquiring about this, I have a frame that just failed.

I have an aluminum road bike frame that cracked above bottom bracket. It cracked almost all the way through the seat tube and the down tube. It was a stress failure as the bike was never crashed and always ridden on the road.

There was no warning except the rear derailleur kept shifting when out of the saddle. I am not a heavy rider (less that 140 lbs) so this bike would have probably failed sooner if used by a heavier rider.

Looking at the crack, it was along the tubes and the welds, so that area was not designed strong enough. The thickness of the tube wall looks less than 2 mm. If the wall thickness was butted (as it was specked) it should have been thicker near the welds.

Seems like the frame company sacrificed strength for a little weight savings.

badger1

So? Frames can fail -- aluminum, titanium, cf, steel. Post is 'not news', and not at all useful to anyone unless you provide more detail/context: what (make/model) is the frame? How old? Ridden how hard?

ramzilla

Please post the make & model of bike + pictures. Thanks.

cale

What age was this bike? What brand and model? Has it been yours since new? How many miles? These are the details that give a reader some idea as to how much use the bike has seen.

Failure at the bottom bracket is an extremely common event in bikes made of any material. An almost new steel bike frame I once bought had to have the bottom bracket lug re-braised because of stress failure so what you experienced is by no means limited to aluminum-framed bikes. All bike frames that are used will eventually wear out. That's why they sell a lot of new bikes. Haha

Fastfingaz

,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,It would be interesting to see the welds of the affected area and other welds and check for signs of under cut , that really weakens the welds and promotes breakage / cracks,,,,,

habilis

I'd be interested in knowing if aluminum frame tubing is heat treated for greater strength, and if welding compromises this strength. Brazing of steel frames requires much lower temps than welding, so maybe less risk of weakening the tubing. Brazing (if it involves brass, as the name indicates) is a bad idea on aluminum, as the two metals react with each other and promote corrosion. I used to think lugged and brazed steel frames were the safest until someone recently posted a picture of one with a broken head tube. It may be that more heat than necessary was used in the brazing process. Speculation is so much fun....

JohnDThompson 

If the frame was made by a reputable manufacturer, it could be defective product. If you're the original owner, you may be able to negotiate a warranty replacement. Good manufacturers tend to be generous in their replacement approvals, if not explicitly in their warranty text as this is simply good public relations at minimal cost to the company (I speak from experience as Trek's warranty inspector many years ago).

OnyxTiger

I'm interested in finding out the details on this frame. Was it a big name brand? Age of frame? Mileage if known? Riding style? Were you the sole owner?

I can appreciate your stating that your frame failed, but without clarifying the other (pretty important) variables, then this post just isn't all that interesting.

SpeshulEd 

So then, once there was a bike and it broke. Gotcha. Very helpful post.

exmechanic89

Yeah please post the brand and more info on the bike, op. Personally I believe chromoly frames are by far the strongest in terms of durabiity, they can truly be lifetime frames if not absolutely beaten to death. I have a lot less faith in aluminum.

cale

Or if they don't rust through.,,

asgelle

What difference does it make? Pick any brand, they've had bikes that broke. Same goes for any material.

exmechanic89

Uhm ok. You truly dont think there's any differeces in frame materials..?

asgelle

Uhm ok. You truly dont think there's any frame material that hasn't broken?

demoncyclist

We want to know so that we can better advise the OP on what steps they might be able to take to get the frame replaced. Most decent manufacturers have a warranty program of some ilk. Some are no questions asked replacement, some have a crash replacement program, etc.

CliffordK

I agree, this could be some Chinese clone, or a common brand-name bike. 100 miles out of the shop, or a dozen years old and 100,000 hard miles.

Is the point just saying that aluminum can fail, just like carbon fiber, titanium, or also steel can fail?

Photos would be helpful. If the frame is being sacrificed, perhaps slice the frame up through the cracks, and parallel to the tubes. Is it truly butted?

SpeshulEd 

When it comes to bikes breaking...nope. But feel free to say which one is better so I can post a picture of it broken.

CliffordK

Any broken classic Schwinn Varsity bikes?

Yes, all the frame materials have broken. Individual anecdotes are entirely irrelevant, but frequency statistics would be nice. Also age statistics. How well will all the new plastic bikes and components age? Some aluminum may also change structural properties with just age.

And, of course, MTBs are often over-built, while the road bikes are under-built.

exmechanic89

No Cliff. that info is irrelevant. Since all types of frame materials have broken, we must conclude that all frame materials have the same durability.

Fastfingaz

Well now that's not nessarally so, durability taken from the word duration ,meaning time,has not been examined or studied, so how long have the different materials lasted before they broke has not been established,,Hmm

RandomTroll

I bought a cheap aluminum frame (Alů, 7005 Alloy, 'Easton Reaction', $200 from Nashbar) 18 years ago. I've ridden it about 100K miles, put a few dents in it, but suffered no mishaps. I broke a braze (seat tube into bottom bracket) of a previous steel frame.

CliffordK

Someone likely has the data. Perhaps you could call Trek and Specialized up and ask them what percent of their CF frames have been returned for warranty claims. Cannondale surely will give you their aluminum data. Anybody want to predict the answer?

One is likely better off evaluating aircraft fatigue data which may be more available, and extrapolating to bicycles.

Maybe data mining in various bicycling forums, but with repeated references to the same bikes, and little control of people posting garage door accidents as frame failures, it will be difficult.

SpeshulEd 

The point is that all materials can fail over time. To not buy a bike or ride a certain material because you saw a picture of it on the internet is ridiculous.

It's one thing if it's a design flaw where there are several occurrences all involving the same material at the same location, however, you don't hear of this happening much among popular brand bikes because they test for these things.

For the OP to make the claim (I think that was what he was doing anyway) that all aluminum bikes are bad because his broke, is an unfair claim...especially with no information regarding the brand, model, size, age, history of the bike.

CliffordK

The responsible manufactures will collect data about flaws, and fix them in the next generation.

That is one of the reasons one often gets an upgrade after a failure. Some will be a whole new model of bike, where the issues discovered with the previous model were fixed (or they just made something new).

I think someone posted a note about a a broken front dérailleur bracket that was replaced with a beefier version.

badger1

Unless and until the OP returns, and supplies appropriate details and context as requested, I think we can safely conclude that this is yet another 'frame material' troll. Somewhat successful though -- gotta give him/her that.