My bike started cracking around the seat tube since the top part of the tube is slightly smaller in diameter than the rest of the tube, which means that only a small part of it makes contact with the seatpost.
I've been trying to look around for people to weld it but haven't found anyone that I trust with it.
Should I just fix it myself? my idea is to cut the portion of the seat tube that is a smaller diameter and insert a new piece of seat tube in which I can then bolt or rivet in.
another pic
>>936640
>people to weld it but haven't found anyone that I trust with it.
why? bike frames are some standard alloy, any weld done by a shop would be fine. you don't even have to repaint it
>>936640
Make sure they strip the paint and clean the metal good. A tig welder should be able to tmdo that for like 50 or 75 to 100 bucks depending on how good they are. They should also be able to level the weld off so you never even knew it was there.
>>936640
Nice pic of your wall bro. Why's the bike in the way?
>>936651
Not op but my Samsung note 4 does this shirt all the time. When it does focus right on the object I'm photographing it's very good quality though
>>936640
/n/ and Shelder Braun would tell you that aluminum frames are pretty much not worth the cost of fixing.
There's a huge chance the crack will just come right back or that you'll weaken the frame in the process.
Even if you did get it to work, a new frame will usually run you cheaper. With aluminum it's only a matter of time til the crack comes back.
It's a temporary solution that would require constant rewelding to stave off.
Hence the origin of the "steel is reel" meme.
>>936644
it's an aluminum frame, can't find which type of aluminum it is right now but most bikes are 6061 or 7000 type
it needs to be heat treated after welding, 6061 heat treatment can be done in the 320 to 350 degree F range, 7000 series AL can be done much lower (room temp if you give it enough time but it is accelerated with temp). You would want to bring the 6061 down to T4 or even T0 after welding to balance the microstructure of the entire part as much as possible, then bring it up to T6.
>>936651
not my fault, the glare messes with the camera and it loses focus
>>936676
>buying a meme bike
>>936676
It wouldn't have cracked in the first place if you didn't have the seat tube all the way up. Get a longer seat tube (if possible) and get it welded.
>>936664
the frame broke because only a small part of the seat tube has contact with the seatpost (marked in black) and that part lies above the weld which is a terrible idea, I want to remove that part and insert a new tube of a similar diameter into the old seattube so that there's a bigger contact area between the frame and the seat post (the blue line indicates the newer tube that I would insert into the seat tube to serve as the new contact point between the frame and my seatpost)
the cost of welding it worries me a bit because I'd have to send it to someone via mail since there are no local people that I could trust with this, luckily I can break down the frame into 3 parts so that helps with both shipping and welding.
>>936696
you mean the seat post? the tube that is attached to the saddle or bike seat?
it's actually a very long tube that reaches past the suspension shock, the problem is that the seat tube expands after the black area that I marked here >>936700 (I'm guessing that was done so that it would fail faster, cause I have no idea why else you would limit the contact area)
never thought about welding the seat post but it wouldn't have helped in any case
>>936640
its a cheap POS folding bike.
not worth getting it specialty welded. they actually tend to be steel because aluminium would struggle with the stresses placed on the hinges and lack of proper trianges
>>936729
it's aluminum and most bikes are cheap POS made in china with a few expensive exceptions that use more expensive labor but no magical materials that make them better
>>936676
Alternatively you could cover it in a comical amount of JB weld expoxy. Just strip the paint and rough up the metal with a file a bit and it would only cost like 10 bucks so....
>>936780
I'd rather fix this one since I like the frame and I spent around $400 upgrading it, the wheels I built myself with XT hubs
post a bike that can break down into a smaller package than this one can and not suck
>>936800
>post a bike that can break down into a smaller package than this one can and not suck
But this one sucks already, so dont imply that it doesnt. Just because you dumped money into a junk bike doesnt mean it was a good investment
>>936802
no it doesn't and the money is never wasted since the parts can be switched out into another frame, which is why I always run a cable through my front wheel and use a $10 saddle
your problem is that to have this properly repaired you're looking at 500$ or more for the expert welding, stripping, oven time and painting. cheaper to buy a new frame. or entire cheap pos wallmart bike
>>936800
you can re-use those parts. just in another 100$ folding bike. I have no idea why you thought building better wheels was a clever idea. its not a serious bike. you build better wheels after your old ones shit out from heavy use. but considering the inherently flawed design and construction of this bike, the original wheels were fit for purpose. this is not a bike that you should be freewheeling down a hill at 80km/hr. this is not a bike that should even be curb hopping. they're for people who want to catch the train then need to walk the next km from the train or ride their bike.
>>936812
This
>>936800
Serious bike nut here.
You're a god damn moron for getting a folding bike with a full suspension.
>inb4 "muh sweet jumps"
I get the convenience factor, i really do. As a person who commuted into NYC proper I used a folder when Id be taking the subways. I get it. But these are specialty bikes intended for one thing. Riding on the street getting from point A to B quicker than walking.
Full suspension or not these bikes ARE NOT meant to be ridden like mountain bikes. There's an incredible amount of leverage against the downtubes with their extended seat posts and the fact they used aluminium with its high fatigue rate in this configuration is mind bogglingly moronic. Whether the downtube shrinks in size like yours or not, this failure is so common on aluminium models that the shop I worked for refused to sell aluminium folders.
Simply put you wasted your money on this frame and ANY attempt to fix it will only be a short term fix to a deeper rooted issue that is a combination in utter failure of engineering, material fatigue life, and misapplication of intended use.
If you do insist on a folder that you'll abuse it must be absolutely be steel so that this exact failure will not happen again.
>>936830
So JB weld till he has money for a new bike?
>>936837
jb weld will not help. it cant handle the dynamic stresses a bike has. would you jb weld an engine mount?
keep in mind OP will be coasting through traffic when it fails.
>>936800
>post a bike that can break down into a smaller package than this one can and not suck
Considering you're rocking some Dahon-knockoff trash that's not hard.
Have you seriously never heard of Bike Friday?
You could sink all the money in the world into this piece of garbage and it will never stand up against even the lowest quality Bike Friday.
Plus, they'd fix your frame for free if you ever managed to break it in the first place.
Hell they'll fix anything for free for the rest of your life in the extremely unlikely event that something breaks.
Yeah it's expensive, but that's like comparing a beat up Chevy to a Cadillac.
You might as well be rolling around town on a children's toy.
Nobody said bikes were cheap.
I hate folding bikes. If it was a choice between walking three miles from the train station, or cycling one mile from the bus stop, I'd walk.
You cannot practically repair an aluminium frame. It is literally uneconomical.
I buy all my frames second hand. They generally last a couple seasons, then snap or break because I'm a fat bastard. But I buy from a charity that recycles landfill bikes, so I get the pick of the stripped frames that maybe have paint too scuffed to be worth refurbishing and selling as bikes, but are still too nice to send to the melting down place. I'm currently using a Giant XtC-3 frame. Cost me £15, came with forks, seatpost, and sram groupset still attached. Was only missing wheels...
I tore it down and rebuilt it with my own parts, but it was a total steal. And when it breaks? I'll go spend another lousy £15 and replace it. Last six years I've spent maybe £40 on my bike, and I've effectively replaced it twice.
>>936830
>You're a god damn moron for getting a folding bike with a full suspension.
(not OP)
Ummm, is it silly to point out here that the problem OP is having has -nothing- to do with the full suspension?
Also, a lot of the better brands/models of folding bikes DO have at least rear suspension, as that.... lowers the shock stresses on the frame....
I would agree that it's generally not worth the cost of repairing a cheap aluminum bike frame, of ANY type of bike.
Usually normal welding places won't touch it due to the thin metals and high stresses involved; you almost have to get it to a place that does bike frame repair specifically.
With the cheapo folding bikes: you should not bother to upgrade them because of the weak frames.
You spend $150 or whatever for a cheapo, and if it lasts a year, you got your money out of it.
A "decent" brand of folding bike costs up around $500 in the USA; it costs more than the ~$400 that a non-folding decent bike costs new. And that $500 price is for a single-speed/coaster brake bike.
>>936857
I've seen a cracked engine fixed with it on YouTube and it ran fine
