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Carbon Fiber Bikes and Longevity(9 posts)

Carbon Fiber Bikes and LongevityKarsten
Mar 30, 2001 9:31 PM
I am in the market for a road bike and I've been looking at quite a few. I'm still trying to decide between a titanium bike such as the Seven axiom or the Merlin Extralight, and a carbon fiber bike such as the Colnago C40 or the Trek 5900. I'm 210 lbs. trying to get down to my "in shape weight" of 185. All the riders and bike store sales people have been telling me different things. One sales person told me that Carbon fiber bikes were not the way to go because after a couple years a carbon fiber bike will become loose and lose all of it's stiffness. "After two years that Colnago will become like a noodle". Another sales person told me that a titanium bike will flex too much for my weight, or if I get the bike built stiff enough it will be heavier than a steel frame. Please offer me some objective opinions on this matter. I didn't think weighing 210 would make it so difficult to find a bike.
my personal experience...4bykn
Mar 31, 2001 6:14 AM
I rode a carbon specialized for about 9 years, and didnt experience any "loosening" of the frame. Just retired it for a new Titanium Airborne, and it will not flex under my 200 lbs, so I would be a little skeptical of what these salesmen were saying. Personally, I refuse to do business with salesmen of any type who bad-mouth their competition. That said, the seven, merlin, colnago (consider the Ovaltitan also) are very good bikes, however I would go with the trek 5500 instead of the 5900 if you were concerned about frame strength. Check the roadbikereview reviews from owners, a lot of good stuff there
lots of bad advice....dave
Mar 31, 2001 7:04 AM
The idea that a CF frame will lose stiffness after a couple of years is totally unfounded.

In fact, no frame material will lose stiffness by virtue of age or amount of use. Frames can break due to fatigue stress, if improperly designed, or poorly constructed, but the tubes don't lose stiffness. Stiffness (modulus of elasticity)is a property of the material. Ti is about 1/2 as stiff as steel, and Al is about 1/3 the stiffness of steel (all else being equal). The stiffness of CF will vary greatly, depending on the orientation of the fibers.

I've got a friend who rides a 61cm C-40, and weighs 225. He has no complaints about the frame. I also ride a C-40, but only weigh 140, so stiffness if of little concern to me. I have to be careful to avoid frames that are overly stiff.

At your weight, I wouldn't be overly concerned with getting the lightest possible frame. A Ti frame may be up to a pound lighter that than an equally stiff steel frame. A CF frame would be 1.5-2.0 pounds lighter than steel. Neither amount is real significant, for a combined bike and rider weight in excess of 200 lbs. You'll never notice the difference. Any of the materials can be made as stiff as you'll ever need.

The best buy in a Colnago would be the Master X-light. Plenty stiff, and cheaper than Ti or CF. Above all, be sure you get a good fit in whatever you choose. The most common mistake these days seems to be choosing a frame that is vertically too small; then come the complaints about bar-to-saddle distance being excessive, followed by cursing the threadless stem and headset.
re: Carbon Fiber Bikes and LongevityIan
Mar 31, 2001 9:05 AM
You can't go wrong with any of those bikes. I weigh 210 and rode a Trek 5200 last year and ride a Look KG281 now. Loved the Trek and love the Look even more. Get whichever of those brands fits you best and you think you will be happiest with. Enjoy your new ride.
baloneyDuane Gran
Mar 31, 2001 1:17 PM
These sales people are nuts in my opinion. Although cycling equipment at the high end is designed with ~160 pounders in mind, it is capable of withstanding much more weight. If there is any area where you will have any concerns it will be wheels, where weight and stress is more likely to cause equipment failure. Any of these high end frames will serve you fine.
re: Carbon Fiber Bikes and LongevityGary
Mar 31, 2001 6:23 PM
I agree with the replies so far. Carbon fiber or any frame material for that matter will not "change" just due to time. Steel may rust...but that's about it. And I would be wary of sales reps that jump out and badmouth other designs. If there was only ONE bike that was truly supreme, then there would be only ONE bike. And there's not.

I'm a heavy rider, 250+, and have ridden a Kestrel 200SCI for over 3 years without any problems. I've even crashed it twice. And amazingly enough, the carbon didn't "splinter into thousands of pieces". My riding style is aggressive as I do also race competitively. My carbon frame mountain bike has held up equally well for 2 years.

I agree with an earlier post that your main concern at heavier weights is your wheels. I use Rigida DP18s and Zipp 440s.

All in all, I think that the frame technology has come to a point where the material is truly second in determining the frame's performance. I've seen carbon, titanium and alumninum frames that are stiff as well as the same materials in other frames that are loose. I think that the primary ingredient to how the bike will perform is its manufacturer (i.e. geometry and architecture).

So will carbon suit you as a heavier rider? Yes. Choose well the manufacturer. Same goes for titanium.
They lie like rugsmoneyman
Apr 1, 2001 7:13 AM
Because they obviously don't know what they are talking about. Everyone is an expert, but ask them to back up what they say with verifiable quantitative data and they are lost. Carbon fiber works pretty well in aircraft, as does titanium, and fatigue and getting "loose" would be a bit more critical than on a bike.

I have a Trek 5500, and it is wonderful. Stiff, yet forgiving on the bumpy roads. The stock Rolfe Vector Pros are as true today, after 1400 miles, as they were on the first ride. And I weigh +/- 200 lbs.

Get what fits.
maybe it last as long but when it does brake do you get a warninjohn de
Apr 1, 2001 7:44 PM
does carbon give any signs of wear or does it just snap or explode 10 years later...
There are warning signs usuallyGary
Apr 2, 2001 4:41 PM
As in all things..never say never and never say always...I'm an engineer, so I would never say this is true 100% of the time, but...

I've not seen any carbon failures that exploded or snapped. I have seen some older pieces begin to delaminate (notably the older Trek carbon frames, but they fixed this problem now with their newer line). And I've seen some wheels that show stress line cracks in the carbon material. I'd say that once you see those things, I would begin to ask questions about its reliability to the manufacturer.