Aww

Hello,
recently I bought a bike with a quite significant down tube dent, a bit too deep for my taste. Not sure what caused it.
Also, I am not really familiar with Alu frames and am generally quite worried about them cracking.
The bike is 91 Trek 7000, Easton 6061-E9 double butted if it helps. Intended use is commuting, which means also some light off road parts combined with going with heavy traffic, so I would prefer to be safe there.
Maybe I am just too cautious, just really not sure about the structure of the dent. Wouldn't want it to crack somewhere, and would prefer not to check it daily during winter. On the other hand, wouldn't want to trash a frame that can still be used.
Any opinion about it is really appreciated, thank you.

Charliekeet

Bummer. Hate to ask, but based on your post, you don’t feel confident about it- so then why did you buy it?

Could it be used? Yeah, it might ride fine for a long time. Would I want to buy it and ride that in traffic?
Nope.

Pantah

I wouldn't be too worried.
I helped a friend build up a late 90's Cannondale (also aluminum) road frame which has a dent slightly larger than that on the down tube and two very large hard whacks on the top tube, plus several other smaller dents and scratches. It lived a long, hard life before and is living a hard life now. This kid rides the thing like he's trying to break it, he's put on at least 2 or 3 thousand miles, tacoed both wheels and the frame is still holding together.

Aww

I also keep asking myself why did I buy it! .)
A person from next village was selling it as a pub bike pretty cheap (and dirty and with most parts exchanged), and I thought I will just grab it and see what parts are usable, as I might even have use for the fork it has in case I trash the frame. Since that I'm just walking around it and thinking whether it is safe to commute on it, as I like the paint scheme and generally would prefer not to throw usable frame away.

Well seems opinions are a bit split and it is true I am not really confident, I'm inclined to not try how long it might last.
Thank you everyone for helping me to sort it in my head kind of .)

grizzly59

If the tube is still straight I would just ride it. You can't pound out dents in Al, but if there is no cracking I'd ride it. The other 345 degrees of tube around the dent are plenty strong. Tube bent, cracks starting down in the dent, dumpster it.

ClydeClydeson

I would ride it. I have never seen a frame break mid-way along the downtube unless there was a significant (as in, the frame is the last thing you will be worried about) crash.

Andrew R Stewart 

The worry about Al is that once a crack has started it tends to travel/grow quickly. (Unlike steel). So as long as you are diligent about monitoring the area you can be safe. But if you don't daily keep an eye on the area and if a crack does start you are not being safe. So it's really up to you. Andy

blamester

Ride it slow for a while. See how it goes.
What condition is the rest of it in?

HillRider

That's a longitudinal (lengthwise) dent so it's not likely for the tube to fail by cracking in half at that point. If the dent were circumferential I'd be a lot more concerned. If it's functional, just ride it as it is but don't throw any significant money at "upgrades".