This is probably the most appropriate board to ask this, so here

>>1187703
Huh, that's kinda fucked up. Can't really offer any insights, sorry.

>>1187703
It's no longer safe to take on the road, but you can mount and oscillating dildo piston to the chain drive and make a perfectly reasonable fucking machine

>>1187703
if it were my bike i'd go ahead and repaint it, then wrap the crack in some asthetic black duct tape and then like 9 heavy duty zipties. But if youre doing anything besides just pedaling around town (trails, jumps etc.) then you can count on that shit failing eventually and no amount of tape and zipties will save you.

>>1187703

You can tell the tube has already deformed around it. I wouldn't ride it again without replacement.

>>1187703
>mongoose

get a new one at walmart or get a nice used trek/giant/specialized/whatever off craigslist

but yeah i wouldn't use that frame

>>1187720
>get a new one at walmart
that's pretty rude

Weld and go.

>>1187703
That's nothing.
Lower part is mainly a tension member so that crack won't do jack. I'd suggest having someone weld it up and then repaint. Clean back a few inches from each end of the crack to see if there is spread. Drill out the ends (stops the crack from running and relieves stress) then have it welded up.

It is an interesting failure though. Could have been a defect in the material. Doubt that metal is DOM (drawn over mandrel) and likely welded up.

It's a shit tier Mongoose...scrap it and start new with a quality bike

>all these pussies
Jesus Christ, bicyclists are the biggest group of wusses. It's a fucking bike, not a car. JB weld it and paint it.

>>1187790
Yeah, it's really weird on this part, since it looks like it was pressed from behind/front, but it's normally subjected to pulling force.
I'm not really worried that something similar happens and obliterates it this time, but the surrounding metal is a little distorted (I can feel it bulging a little near the crack when I run finger along the chainstay), so the structure is probably more susceptible to stress and any vibrations and shocks may result in spreading.
Also, from what I read about aluminum welding it requires some special kind of heat treatment afterwards, otherwise I risk it getting more fucked than before, so there is that.

>>1187703
>Weld
>sand flush
>paint

>>1187703
If it was steel you could just get it patched/welded but im not sure what your options are with aluminum. I wouldnt trust it. also it's 18 years old and a mongoose so it's probably not a big (monetary) loss anyways. take this as an opportunity to get a new bike

>url on an 18 year old bike
are you sure about that?

>>1188029
>1999

>>1188029
>1999-2000
>url

sounds reasonable

>>1188029
We had interwebs back then...dialup though...

>>1188039
no, no it doesn't

>>1188067
why not?

>>1188067
I want underage to leave
I was furiously fapping in my mother's room to Internet porn [spoiler]images[/spoiler] in 1997. On a 28.8k modem.

hii

>>1187703
>but it's aluminum, so the structure is already fucked
It's not a big deal where it's located.
>>1187790
>Drill out the ends (stops the crack from running and relieves stress) then have it welded up.
Do this.
>>1187790
>It is an interesting failure though.
It appears to be caused by water inside the member freezing.
I'm not sure how water got inside or whether it was ever left in an area where it could freeze - but that's what it looks like.
If you have it repaired drill a small (1'8") hole on the bottom side at the lowest point of both members so any future infiltrations of water can get out.

>>1187755
>>>1187720
>>get a new one at walmart
>that's pretty rude
Does that trigger you?

Alright, thanks lads. I'm gonna do what >>1187790
suggested minus welding. After some consideration it doesn't seem that part is really affected by the crack during normal operation.

>>1187703
Weld it so it doesn't crack further, make sure you get the weld right into it and if you can pinch it once it's hot (you say its aluminium won't be hard.)
Then just grind down any tacked on weld and sand down, should fill it and fix it.

Zip ties can work wonders for stuff like that. Put some on, and tighten them as often as you can

Only 2 proper fixes:

Grind off old paint, find and then drill ends of crack

then either fill with welds, or cut this section out and replace it. I would just weld it

>>1187703
>mongoose
considering a crack is either a whole frame overhaul or throwing the bike in the garbage, I'd have to say the bike is finally going where it belongs

>>1188114
>It appears to be caused by water inside the member freezing.
Didn't think of that, but certainly is possible. Pressure from ice could have popped an already week weld or stress line.

>>1187797
>aluminum welding
Yes, a pain. But there are cheaper options for low stress joints. Google alumiweld rods or look in youtube for brazing aluminum.
Ain't pretty but it will work to keep crap out and stop the crack from getting worse.
Not a shill, but I have fucked with those rods before. Fixed a busted radiator and saved my ass a few hundred bucks. Worked till I sold it.

>>1187709
Or get a new bike and make the fuck machine road safe.
Maybe not very legally usable, but road safe, and definitely fun on mountains

what's with all the mongoose hate? is it some kind of synonym for shit in the US? it was a pretty decent bike, lasted me years and I did 0 maintenance on it and never had to replace anything. that being said, I only ride about 100km per week during spring/summer

>>1189734
>what's with all the mongoose hate?
they used to be decent bike store bikes, then walmart exclusives

>>1187783

This. Tig weld. Add a bunch of material (weld) and then grind to taste.

>>1187711
this

>>1187710
Zip ties? Seriously? Take it down and have a bead welded on it anon then you're good to go.