Road Bike, Cycling Forums banner
1 - 20 of 21 Posts

·
Home Brew User!
Joined
·
2,810 Posts
Discussion Starter · #1 ·
More and more CF is getting a rep of being a little on the ‘brittle” side. While I think it is a design issue and not a material issue, I do think there is some truth to it. I suspect that CF is following Aluminum’s history and any issues are directly related to wall thickness.

Anyway, Is there a particular CF frame that would be considered a Tank. It seems as though you could make a CF frame that was damn near indestructible.

Being very familiar with quite a few Aegis frames, I suspect their cross frame is pretty close but I have never been able see one in person.

Does anybody knew of some really strong CF frame that’s available. The cheaper the better.
 

·
Registered
Joined
·
2,078 Posts
The Look 585 is a tank.

The round tubes are not oversized so the wall thickness is maintained. And to a lesser ecxtent but still pretty good the Time VXRS. Both use full carbon lugs.
 

·
So. Calif.
Joined
·
2,800 Posts
ewitz said:
The Look 585 is a tank.

The round tubes are not oversized so the wall thickness is maintained. And to a lesser ecxtent but still pretty good the Time VXRS. Both use full carbon lugs.
Both the Look & Time are quite light, around 1000g for frame-only.
"Tank" implies durable and heavy ... Look & Time are durable but certainly not "heavy".

Lifelover said:
More and more CF is getting a rep of being a little on the ‘brittle” side.
Is this a surprise?

Certainly CF is not ductile like steel ... neither are typical aluminum alloys used for bikes.
But CF can be very strong, and has fatigue strength exceeding steel, Ti, and aluminum.

Autombile windows don't spontaneously break from just driving around on rough roads, but a sharp whack with a hammer will break glass.
 

·
Steaming piles of opinion
Joined
·
10,503 Posts
You could get a steel bike and wrap it in this.

Approximately the same result. Except better.
 

·
Registered
Joined
·
2,078 Posts
tom_h said:
Both the Look & Time are quite light, around 1000g for frame-only.
"Tank" implies durable and heavy ... Look & Time are durable but certainly not "heavy".
I can only speak from experience.

I bought both of those as much for their durabilty as their light weight.

I treat both less than gently and neither is the worse for wear. To many of the bikes in their price range won't stand up to any abuse with their large diameter thin walls. I know that I would puncture the frameset in the back of my car againt a wheel or pump or another bike.
 

·
Dr. Flats a lot
Joined
·
740 Posts
Orbea Opal

While not a tank per se, it was specifically designed to not break when you crash it. It was also designed to race at the top level. Not many of them around as it is a total redesign of the old Opal, but saw a bunch of them at the Tour of California. I just got mine, but have not finished building it, plus there's 1 ft of snow on the ground so I'm not rushing. It also has a lifetime warrentee and is pretty inexpensive is comparison.
 

·
Registered
Joined
·
21,636 Posts
Fatigue

tom_h said:
But CF can be very strong, and has fatigue strength exceeding steel, Ti, and aluminum.
Considering that steel and Ti have essentially infinite fatigue life, and that "fatigue strength" means exactly what? What is it you're trying to say/claim here?
 

·
So. Calif.
Joined
·
2,800 Posts
Kerry Irons said:
Considering that steel and Ti have essentially infinite fatigue life, ...
Only if the stress is kept below a specific limit. Eg, see chart at http://en.wikipedia.org/wiki/Fatigue_limit

Anecdotally, steel frame Mfrs are very conservative. One or two riding partners are still on very nice, 15+ yr old, steel frames.

I had a lovely, late 1980s, steel frame, Trek 850 MTB that I "gifted" to my son ;-)

One of my riding partners did suffer a failure in his Ti Litespeed frame, near the bottom bracket. But we both suspect it was more likely a flaw in the welding workmanship, than an inherent material property.

In messy "real life" applications, material interfaces -- including the HAZ (Heat Affected Zone) -- are the troublesome areas, not the homogenous bulk.


http://www.calfeedesign.com/whitepaper4.htm
" ... Carbon fiber also has a better fatigue life than steel, titanium, or aluminum, ..."
 

·
Registered
Joined
·
218 Posts
I know you are not going to like this response: Motobecane Immortal. Lots of them out there and I have come across no reports of frame breakages. From the surface their design looks tank like.
 

·
Registered
Joined
·
330 Posts
Look KG461 - not completely CF, though, since it has aluminum lugs. It's still a smooth ride, feels durable, and the frame/fork/headset weight is about 2 kg, about the same as an aluminum frame/ aluminum-cf fork.
 

·
Registered
Joined
·
994 Posts
Lifelover said:
More and more CF is getting a rep of being a little on the ‘brittle” side
This has always been a perception of carbon, and one that carbon seems to always have to disprove and overcome.

Having ridden two carbon bikes over the years, I found them all very structurally solid and no complaints. Remember, the majority of road bike forks are carbon today, so if it was very brittle and not tank like, we'd have many fork breakages by this time.
 

·
trying to HTFU...
Joined
·
1,875 Posts
i'm still riding my 1990 Kestrel 200ems; it's not tank-like weight-wise
but has been extremely durable and has the classic smooth, solid ride.
frame weighs 2.4lbs w/EMS fork, but built up is around 19lbs.

my friends call the ride, 'dead' but that's OK, it doesn't beat me up on epic
rides. i am riding my new full carbon QR Caliente tri-bike a lot more
though, so the Kestrel is getting a little less love than she used to.
 

·
Registered
Joined
·
62 Posts
My Giant OCR Composite Limited is amazing. The head tube junction is one the beefiest I've ever seen in a road bike, and the other major tubes are fairly oversized too. It's a cliché, but it's laterally stiff but rides like a magic carpet.

It's slightly heavy for a carbon bike too; 19lbs without bag, bottles or gps and that can't all be explained by my components. (The triple, saddle and deep V rims only add so much, and everything else is standard Ultegra or light Thomson.)

I'm 265 and flex traditional-tubed steel frames like they're fishing poles, but this thing... standing, hammering as hard as I can, it just goes straight forward. Amazing bike.

 

·
Registered
Joined
·
603 Posts
Lifelover said:
More and more CF is getting a rep of being a little on the ‘brittle” side..
I'm honestly not being sarcastic here - it's seemed to me like the more the price of carbon bikes goes up, the more talk there is about how carbon is "brittle" and "fragile", etc etc. No one wants to believe that they suddenly need to spend $4,000 to get a really decent bike (not saying you do or don't, just saying no one wants to think that way - like, I don't either :)).

They make mountain bike out of carbon fiber nowadays. If you want a tough, non-racing bike I'm get a bike designed to be beaten up on the corse, like a mountain bike or tricross bike. That way you know they designed it to take a pounding.
 

·
Home Brew User!
Joined
·
2,810 Posts
Discussion Starter · #19 ·
Tanks for all the replies.

I'm not in the market for a new frame but was wondering if there are any CF frames marketed as being "tanks".

I would like to see someone like BD make and market one.

I'm not a believer that CF is brittle by nature but I know that the wall thickness is getting thinner and thinner. Find a Scott dealer and ask if they have the standard cut away section of a frame. Amazingly strong but scary thin.
 

·
Registered
Joined
·
374 Posts
Lifelover said:
I would like to see someone like BD make and market one.
BD makes nothing. However, the ADK frame on BD Motobecane Century and BD Bottecchia CF bikes is as close to a tank in CF frames as it gets, indeed.
 
1 - 20 of 21 Posts
Top