Dented Aluminium frame - ?

[simongt]

One of my pals wants to buy a suitable bike for winter use. He's seen a Cannondale CAAD8 roadbike for £300. Looks in good condition; however - ! There is a dent on the top tube which I would say is cause for concern. The dent is about halfway along the tube and is a vertical crease, looking like it was done with something with a hard edge. The whole dent area is about the size of a 10p coin with the crease goes in about 3 - 4mm and is about 15mm long. The paintwork appears to be unmarked, but is this dent cause for concern - ?
I've never been a fan of alu alloy frames, but I do know that they don't take kindly to getting hard knocks.

Your sage advices would be appreciated - !

 

[Drago]

No shortage of used bikes at keen prices. I'd go find one that hasn't got a dent.

 

[biggs682]

another vote for walking away

 

[screenman]

It is weaker than before the dent that is for sure.

 

[growingvegetables]

I bought a similarly dented alu frame - mainly because I wanted the components for another bike.

However - it was a real pleasure to ride, and I kept riding it. The dent in the frame hadn't weakened it as far as I could see or hear. It was a joy.



Umm - note the past tense. The top tube gave me no trouble, but the frame snapped at the rear drop out. As I was riding uphill on the busiest dual carriageway in Leeds. (Two minutes later, I'd have been doing 30mph downhill.)

My tuppenyworth? Anybody daft enough to ding their top tube so badly, has very possibly/probably/certainly (your choice!) done some serious (but less visible) damage elsewhere. Don't touch.

Except to cannibalise

 

[screenman]

A dent in a tube makes it weaker, however if the tube will ever fail or not is mainly unknown.

 

[Illaveago]

Some alloys can be incredibly strong, so the force needed to cause the dent may have been quite substantial.

 

[Yellow Saddle]

A dent such what you described doesn't make the frame weaker. Anyone who disagrees has to explain why and how. Further, aluminium is soft, just letting the bike fall over on a step or railing could cause such a dent. It isn't a sign of a huge impact at the upper end of the Richter scale.
If it is the right size, colour and price, don't hesitate. Dents are like scars. Chicks dig them.

 

[Drago]

Would you buy a car with a dent when there is a ready supply of cars with no dents? So why with a bike?

 

[earlestownflya]

if the dent concerns him,don't buy it...if it does'nt, buy it,just looking at it would put me off

 

[Svendo]

A dent such as what you described doesn't make the frame weaker. I want anyone who disagrees to explain why and how, but have no right to compel them. Further, aluminium is soft, just letting the bike fall over on a step or railing could cause such a dent. It isn't a sign of a huge impact at the upper end of the Richter scale.
If it is the right size, colour and price, don't hesitate. Dents are like scars. Chicks dig them.

FTFY

 

[jonny jeez]

Would be worried that a dented top tube is related to something else.

Could it be possible.for.the bars.to.have.come round on a front impact.and struck.the tube.shall have to test this theory on my bike tonight.

Its common on motorcycles for.the tank to.collect a dent.from bar impact...not.sure.road bike.bars.can meet the frame.

Either way, too much choice available to accept a dent that will be in your line of sight forever more.

 

[simongt]

Thanks for all the feedback. My pal is looking for another steed - without a dent - !

 

[Drago]

FTFY

Indeed. Or better still, perhaps he could explain how damaging a tube designed for maximum strength for a given weight doesn't weaken it, or why the CAA don't allow dents on structural tubes.

 

[Hover Fly]

Ever done that thing where you stand on a beer-can and it takes your weight, then put a small dent in it and it doesn't?