Question about aluminium frame challenge to carbon fibre frames?

[Mr Celine]

My Boardman alloy bike was used every winter on snowy and salted Dales passes, because I found it fun to ride (or try to) a narrow tyre road bike in such conditions. I had no idea how the stressed area around the bottom bracket welds (the tubing just beyond the welds) had corroded inside, and possibly been weakened, so I laid it up and bought a carbon fibre bike. (Spesh Roubaix)

Remove the bottom bracket and have a look inside. That's what I did, and found very little corrosion visible (a light dusting of powder) inside the bottom bracket shell and none at all that I could see inside the frame tubes of the Sirrus pictured upthread.

 

[I like Skol]

OK. I bought an Alu framed hybrid in 2010 - https://www.cyclechat.net/threads/2010-gt-traffic-1-0-hybrid-any-reviews-experience.66029

Rode it hard until late in 2018 this happened - https://www.cyclechat.net/threads/what-bike-to-replace-my-dead-hybrid-commuter.240346/

So 8 cruel years of all weather urban commuting with gritted roads in winter and plenty of loutish hooligan behaviour in between (riding down stairs etc). Covered just slightly shy of 20,000 miles and in the end developed a fatigue crack in a cast(?) dropout rather than any of the tubes, welds or forks. Crack was discovered during rare routine maintenance and even if it hadn't been spotted then I don't think it would have resulted in a life threatening catastrophe when it gave up all together.

Cracks in MTB frames and road bike frames also noticed during irregular inspections.

IMO Alu is quite safe unless you ignore the signs.

 

[cougie uk]

Does it sound any better if I say I'm nearly 50, work 12hr shifts and religiously don't 'train'?

Is anybody else riding these climbs ? Where are all of the keen riders ? Very strange !

 

[Rain drops]

People are not always rational. I'm no exception! As with all here, emotional reactions sometimes lead me by the nose.

I dislike aluminium alloys for the grief (not to mention replacement costs) it has caused me in my long standing fanatical passion for my chosen sports. An illogical reaction no doubt, but that is what colours my feelings.

I don't have to justify this stance to others, and if they see it as wrong, that remains my problem. (Enough are telling me so.) If others are truly convinced that there is no problem with using aluminium alloys in bike builds, that's their problem, in my opinion! Surely it's now quite clear where everybody claims to stand.

 

[matticus]

7 pages to get to that! And we've recycled the same old same old in 90% of these posts :P

I sometimes think "frame material" threads should get their own ghetto, like h*lm*t threads ...

 

[fossyant]

People are not always rational. I'm no exception! As with all here, emotional reactions sometimes lead me by the nose.

I dislike aluminium alloys for the grief (not to mention replacement costs) it has caused me in my long standing fanatical passion for my chosen sports. An illogical reaction no doubt, but that is what colours my feelings.

I don't have to justify this stance to others, and if they see it as wrong, that remains my problem. (Enough are telling me so.) If others are truly convinced that there is no problem with using aluminium alloys in bike builds, that's their problem, in my opinion! Surely it's now quite clear where everybody claims to stand.

That's just you then. Feck all wrong with alloy frames.

Someone keeps bleating about rusty steel. Erm, I've got 3 30 year old steel bikes, all of which are in regular use, and one aluminium MTB that get's some serious abuse - but it meticulously maintained - suspension isn't cheap.

Plenty of horror stories about carbon components and frames - just for balance, especially dodgy fakes. Plenty of big name carbon MTB's snap.

 

[Dogtrousers]

I only have ever had steel bikes (and very few of them, I'm not an N+1 person) but from this thread I've learned:

All frame materials may be subject to failure. Sometimes due to manufacturing fault, sometimes due to fatigue and old age.
Any bike frame can be expected to last pretty much indefinitely, just do periodic inspections.
Different materials suit different use cases (think carbon for sporty road riding, but not for MTBs, steel for cool cats )
The original thrust of the thread - that there is a "challenge" to carbon frames from aluminium ones is probably not the case.
Some people have favoured materials (which is quite natural) some people have irrational dislikes of other materials (which is daft, but that's how people are)

 

[bonzobanana]

Really the thing that compromises lifespan and durability of frames is designing them for performance, at that point you are trying to save weight and making compromises to achieve better performance. You can over-engineer a frame with any material or you can make it exceptionally weak by making it too light. However no one really makes over-engineered carbon fibre frames because there are better materials for that and aluminium generally is the middle level of performance I guess overall for road bikes but for mountain bikes you definitely get over-built frames made of aluminium. High tensile steel will never be a performance material its clearly a cheap material and there is no reason not to over-engineer it really because plain gauge standard tubes are the cheapest.

It's like any component really, you can have a long lasting steel cassette but is heavy or you can have a aluminium cassette perhaps with steel or titanium used for the smaller cogs and then you can have a carbon fibre carrier to hold the cogs and you can drill the cogs carefully to remove material without compromising strength much. The cheap cassette is still stronger and will last longer but at the expense of weight. You can understand all the extra processing and the more exotic materials add hugely to costs and you have added many more possible failure points and shortened its lifespan. So a steel cassette might last 10,000 miles (just a guess) and the more exotic cassette perhaps 6,000 miles but the cheap cassette costs £15 and exotic cassette £150. So one is 0.15p per mile in cost and the other is 2.5p per mile. That's like 15x as much per mile. Lets say there is 200g weight difference though.

My point is generally performance compromises lifespan of any component really be it frame, cassette, wheels, saddle, derailleur, tyres etc. The more you push for performance the higher the costs, the shorter the lifespan and the worse the value of that product. I totally accept that sometimes products are compromised by price as well, the product is just too cheap. It could be a carbon fibre fork that only has carbon fibre blades bonded to an aluminium steerer or could be a plastic derailleur with a weak spring giving less than ideal functionality. It's really the two 'P's that compromise bike design with regard safety and lifespan and thats price and performance. As ever the value conscious buyer looks to find the sweet spot when he/she buys a bike.

 

[Rain drops]

Thank you for your reply Bonzo. It clarifies what I was getting at.

I have ended up with two good for my needs road bikes, both of which are Specialized Roubaix. The older one is rim braked 2x9 and the newer one is disc braked 2x11, because from what I've read of that company design and build philosophy I believe, rightly or wrongly, that they err on the side of safety and longevity. I accept that they are not the best value for money with regard to group sets, but I would rather have a less well equipped bike with a soundly designed and built carbon fibre frame, than the other way about. (Yes, I know they contract out the frame building but it is built to their demanding specification and quality controls.)

I hope both of these bikes will see my road riding days out until, in 5 or 6 years time (at 90) I have to resort to an electric road bike.