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Frame weld
#1
I have a 2004 FUJI Provence 64cm. I am 6'4' and 280 lbs. I have almost 6000 miles on this bike and have been wondering a lot lately how much of a toll my weight has been taking on the frame welds. Besides visually inspecting the welds for cracks, what else can I do to alleviate my fears of a catastrophic failure?
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#2
Well, it is a road bike, so you don't "abuse" it like you do with an MTB. I have not found the frame specs, but unless those say you are too big for the frame I wouldn't worry too much. What might fail first are the wheels, some have restrictions on rider weight.
That said, inspecting the frame for visible cracks is always a good idea.
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#3
Dings and dents are another thing to look out for, Joe I'm not sure of this but paint chips?
Good maintenance to your Bike, can make it like the wheels are, true and smooth!
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#4
hm. Depends on the material. If it is a steel frame I'd worry about rust, if it was carbon I'd worry about the structural integrity. On an aluminum frame I'd not worry about chipped paint too much.
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#5
(03-03-2010, 03:12 PM)Joe_W Wrote:  hm. Depends on the material. If it is a steel frame I'd worry about rust, if it was carbon I'd worry about the structural integrity. On an aluminum frame I'd not worry about chipped paint too much.

The frame is aluminum except for the seat stays, they are carbon. I don't ride in the rain often so I am not worried about corrosion. What I am worried about is metal fatigue. When I climb hills I torque the frame just from my sheer weight. I just wondered if there was some sort of "rule of thumb" as to how long a frame is expected to last under these conditions. I usually ride in hilly terrain so I climb 50 % of my rides. In the welding trade there are other ways to check welds, such as stain testing and xrays. Has anyone heard of that being applied to bicycles?
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#6
Stain testing or x-rays? Seriously? Unless you have health coverage for your bike, you're going to pay more for those tests than you would for a new frame.

If you're really worried about it, sell the frame, and use the money for a deposit on a custom frame that a frame builder will reinforce the hell out of for you.
Dedicated scholar of bicycles
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#7
The moving parts will give out before the frame in that environment. Like when you are going up hill the chain or pedal will more likely to break before a seat or down tube weld. Your handle bar, stem, or upper steerer tube would give way before the upper down tube weld. Now that is under normal circumstances, if there were to be a defect then yeah maybe. Other then that, its all I know lol.
Good maintenance to your Bike, can make it like the wheels are, true and smooth!
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#8
Agreed, Bill. I would also stay clear of extremely lightweight handlebars and seatposts if you want to be on the safer side. I recall reading somewhere that those sometimes need to be replaced after one or two seasons (depending on how much you ride).
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#9
(03-04-2010, 10:47 AM)Joe_W Wrote:  I recall reading somewhere that those sometimes need to be replaced after one or two seasons (depending on how much you ride).

That's not true at all if you're referring to carbon parts. Carbon has a MUCH higher fatigue life than any metal you'll find in bike components. They should last you a TON more time.

BUT, if they are over-torqued, it can reduce the life of the component to maybe even hours depending on how much it was over tightened. My brother did it with his brand new Profile bars. Thought he could do it by himself. They lasted 5 days.

They should also stand up to weight better. Carbon has a higher strength to weight ratio than aluminum too. So depending on the layup schedule of the manufacturer, a carbon component can weigh the same as an aluminum, and be a LOT stronger.

Find some heavier carbon compnents. They'll last a lot longer.
Dedicated scholar of bicycles
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#10
Well, you can do it by yourself if you have a torque wrench...

And: no, I was not talking about sturdier carbon parts but rather about thin walled, lightweight aluminum stuff. I have to search where I read this, depending on the context it can be dismissed.

On the fatigue life: There was a test in Bike Magazine (German MTB mag) last year where they did compare frames with comparable specs (aluminum, steel, carbon) and carbon did win, by a high margin (as expected). I used to do soaring so it did hardly surprise me (modern planes are built from CFC and glass fiber).
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#11
(03-03-2010, 09:42 PM)yetti Wrote:  The frame is aluminum except for the seat stays, they are carbon.

The weakest part of the frame is probably the joints where the carbon and aluminum tubes meet. Both materials are plenty strong for years and years of use, but the joints do have more stress on them due to the different properties of the two materials. I'd inspect those joints once in a while for any cracking, flaking, creaking, etc.

That said, almost any decent frame should last you many years. I think the "replace every couple years" thing is a myth circulated by shops looking to sell bikes. There's also long standing rumors about metal frames "getting softer" over time that are also completely false. Frames do brake and it also makes sense to look things over, but any kind of high-tech analysis is probably a big waste even if it exists.
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