sonnycrockett

I'm considering buying a bike with a dented top tube. The frame is made of Columbus Nemo light weight steel. Do you think it's too damaged to even consider?

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Chop61

Don't buy this trouble.

FBinNY 

It probably won't matter, depending on how it got dented. If in a crash there might be other not so visible damage, though if it was done with a baseball bat during an attempted robbery it's probably OK, being in a not highly stressed area.

My advice is to stay away, unless it's so cheap you can take it on a flier. I don't think there's any danger, except for the financial loss if it doesn't ride well.

Loose Chain

A very small dent is of no concern for practical purposes but that is a pretty significant dent. The tube would need replacing or other type of repair.

Contrary to popular belief, the center area of a tube span is indeed critical for columnar support. Large, deep dents in that area should be avoided.

BCRider

That's a sizable dent. Also the top tube is operating under a high compression load. (sorry FB but it's not a low stessed tube) with all your weight trying to collapse it together. And that load is increased when you hit bumps in the road.

Ever see the trick of standing on a pop or beer can? If the can is pristine and you very carefully stand up on it taking care to load your foot squarely and evenly around the top the can can hold up a 200 lb adult. But then if someone oh so lightly taps the side of the can with a pencil the cylinder is distorted just enough and the can collapses explosively. It's actually great fun at parties and is superb for reducing the volume of post party trash....

But the top tube is like that pop can. It's holding the seat tube and head tube apart and is under the stress of your full weight. So buying and riding this frame would be like trying to do the beer can trick with a dented can. When you try that you're lucky to get up to 1/3 to 1/2 your weight on the can before it lets go due to the imbalance of the forces in the cylinder. Those same imbalanced forces will be at work in the dented area of that top tube.

OK, OK, so bike frames are not beer cans. But the priciple is there. And that's a freakin' big dent. And the top tubes on high end frames are not all that thick. A small ding I'd have no fear about buying. But this is far more than a small ding. That frame is trash.

sonnycrockett

Thanks for all your advice. As hard as it was to pass up--the seller was asking $250 for a 2000 Marin Treviso!--your input and my better judgement won out in the end and I walked away. Needless to say, when something is too good to be true...

sonnycrockett

Oh, and may I add that I'm now considering a 1992 Bridgestone RB-2 in near mint condition for $350. I think the extra hundred will be money well spent!

Roaddaddy

I bought that one. Great bike! Had been ridden for years with that dent, don't think it's going to be a problem.

DiabloScott

Here's the acid test: sit sideways on the top tube - put all your weight on it, bounce around even. If it doesn't buckle under that load it won't buckle under any conceivable riding conditions. If it does, you didn't want to ride it in the first place.

Thumpic

why would you risk it? if it were free and broke all your teeth out when it failed would it have been worth it?? wait on something better/safer.......

BCRider

If you KNOW it had then fine. But these days I sure wouldn't take someone's word for it at face value. Just far too many people out there willing to say anything to make a sale. Also if the previous owner was a lightweight and the new owner a heavy weight what worked then may collapse under the new load. Far too many risks to justify it IMO.

Roaddaddy

@BCRider - I met the guy and do believe him. The dent was caused by a collision with a garage while it was riding on a car-top bike carrier. It was the type where you take the front wheel off, exposing the top tube.

@Diablo, Thumpit -- I like my teeth where they are. I will try that test out -- is that a fair test for any bike? At 220, I'm probably 30# heavier than the prior owner. Thanks for your concern. The bike is a very sweet ride, hope it doesn't fail the test.

Camilo

Not only the possible danger, but who could ride a bike looking at that ugly dent every time? There's a lot of bikes out there, get an undamaged one.

That bike is worth exactly what the rest of the parts are worth, maybe a little less since you have to remove them to put them on a new frame. JMHO of course.