I visit two different bike shops today that gave me completely different information, so I figured I'd ask here to get to the bottom of this.

One said aluminum frames are stronger, can withstand crashes, and can be fixed if a serious crash does occur. The owner said carbon frames are light, but also fragile--when broken, they cannot be repaired.

The other said carbon frames are stronger, can withstand crashes, and can be fixed if a serious crash does occur. On top of this, he said aluminum breaks in crashs and when broken, cannot be repaired.

So, which is the correct information? I'm looking into purchasing an endurance road cycle to ride from Seattle to DC (not touring, I'll have a van and crew following the team with all our gear) and need to make a proper decision.

Get a bike that fits your body.
Any frame will do.

Truthfully, the people most qualified to answer this are the ones in the Framebuilders forum. Moving this discussion there.

I moved this from General Cycling in the hopes that you knowledgeable folks can assist the OP without setting off a holy war.

Thank you!

Every frame material has advantages and disadvantages. In the mid-nineties, Scot Nicol, head of Ibis, wrote a series of six articles for VeloNews called Metallurgy for Cyclists. These articles explain the physical properties of the different materials used for making bike frames, and although they were written nearly twenty years ago the basics haven't changed that much.

Start by reading the articles: Metallurgy for Cyclists

The idea of repairing crashed frames with real damage to them is kind of an urban legend for most people. It can be done on all materials to some extent (though it never seems to make much sense on Aluminum). But, if your bike isn't super high end, it will NOT make sense financially.

Minor bends without buckling in steel can be repaired easily, but major damage requires expensive repairs.
Aluminum often requires heat treating for welds, and is trickier to repair in general.
Carbon repairs are risky for folks who don't specialize, and there's only one or two places that really focus on that.

Any of these options will likely cost more than a replacement frame unless your frame is SUPER sweet. Like, a frame on a 5k total package bike sweet.

All frame materials can make a bike that will stand up to all normal riding and abuse for ages. If there's a catastrophic crash, any frame can be destroyed. Some are slightly more resistant... but there's a ton of variation frame to frame as well. There are carbon frames that are stronger than aluminum ones, and vice versa.

There are more instances of "better safe than sorry" canning of carbon frames, because damage can be harder to evaluate... but realistically, if they were actually a lot more prone to failure than other kinds, they'd be rarer due to liability.

Ride some bikes, find one you love to ride. Buy that bike.

SOURCE: Worked in bikes for 6 years, seen a lot of frames come and go. That covers the "what will they survive" angle. As far as the repairs angle, I just lurk and watch outcomes on the "how do I fix this?" threads. There are not a lot of great outcomes.

lots of people are repairing carbon nowadays. Very few people repair aluminum. Considering that most LBS aluminum bikes are low-end, that isn't going to change. You can get anything fixed, it's just a matter of economics. Usually it's not economic to repair

Yes lasting repairs of a critical failure of a frame of any material is generally cost-prohibitive. Many small repairs (say stops and bosses) can be done quickly and effectively on all materials but nonetheless requires specialized skills and tools. There is a wide spectrum of possible failures and repairability should be down in the list of priorities. If you have a support crew it makes sense to carry a second bike; McGyver repairs done on the fly will not last.

For an endurance ride you need a bike you are familiar with and that fits well.

not sure I understood the question correctly. If on-the-road repairs are needed, you probably want to go with steel, and even then you are risking long delays. Just saw a steel frame get taken out over the weekend -- derailleur failure on a long downhill.

Planning for many crashes.

Carry spare bikes in the chase vehicle.

You could have Aluminum, Steel and Carbon.

Just don't let this happen:

Any crash that is severe enough to cause frame damage is likely going to end your ride. I wouldn't worry about the ability to repair a frame. You want low weight and aerodynamics.

Plus, it is not exactly as if you are riding through uncivilized wilderness [insert joke here about your least favorite urban centre]. With a credit card and a cell phone, there is likely no more than 2 hours between you and a replacement bike.

Alu frames are not worth repairing. Bike Nashbar sells a $200 alu/carbon road frame that is about as good as any made before the top-end bikes went to carbon. All of the high-end bikes are now carbon.

I have multiple bikes iin all materials. Carbon is the performance leader, with titanium a close second. Alu can make a great bike as well. Steel, bamboo, polystyrene, plutonium etc. fall into the "thanks for participating" category.

we don't do materials religious wars in framebuilding. But thanks for playing

I hate when that happens. Makes me think the employees don't ride bikes themselves.

-Carbon is repairable. I've seen it on youtube and on instagram.
-The characteristics (i.e. strength) of carbon depends on the layup of the carbon.
-Aluminum CAN be as light as some carbon frames.
-Metal dents-carbon cracks.
-Even aluminum frames with dents in them are ridable, but are very hard to repair.
-Riding a cracked carbon frame is risking injury/death.

I have always understood that carbon bikes are more prone to "fall over" type damage. I have always assumed that scratches dings nicks etc are more of a concern with carbon bikes. I suppose this is an issue with all materials, but a small ding or dent an an aluminum frame would be much less concerning for me than one on a carbon bike. Can anyone offer some clarity here?

I won't comment directly on this, but will refer you to the articles at the link in post #6 above.

"The Basics" article discusses the nature of physical, mechanical and chemical properties of different materials. Physical properties are things like density, color, electrical conductivity, magnetic permeability, and thermal expansion. Mechanical properties include things like elongation, fatigue limit, hardness, stiffness, shear strength, tensile strength, and toughness. Finally, chemical properties include reactivity, corrosion resistance, electrochemical potential, irradiation resistance, resistance to acids, resistance to alkalis, and solubility.

Since you asked specifically about carbon fiber, read the article "Carbon Fiber Boasts Tremendous Potential" and note what it says about elongation.

a ding on an aluminum frame can lead to cracking in fairly short order, so it's not a given that it's more forgiving of dings. If a carbon bike gets hit the wrong way, it might delaminate the fibers. This will probably reduce the section strength considerably.

Carbon the molds they are laid up in is where the investment is made, and there is lots of hand labor ..

Aluminum the welding work to put it together is on the material itself.


Then there is the post welding normalization , and heat treatment ..

Think Backups, buy a couple bikes so you have a spare , problem solved,
might invest in extra spare wheels too.

Lots of generalizations there. You can get strong light carbon,aluminum,steel, titanium, etc. that would let you ride cross country without failure. The failure modes are different between materials. Rather than focusing on what might happen (ie need a fix) the focus should be on well the bike fits and how it feels on the road. Price isa also normally consideration. Seattle to dc is a long ride and if you are going to be in the saddle 10-12 or more hours a day you are going to want a bike that is comfortable that many hours a day. Many people will say aluminum is going to be much harsher than other choice for such ride, but you would have to try the bikes out for your self.