Dylansbob 

So I had a crackhead break into my garage to get my motorbacon 29+ss. Since it was locked, they tried to hacksaw through the downtube. They made it almost halfway before giving up and trying to get into my basement where the rest of my good bikes were.

But anyways, so I've got this severely weakened downtube on a bike that isn't easily replaced. I'm wondering if a simple epoxy-soaked wrap might be my best option of salvaging a few more miles out of the bike. Or shoud I go full-bore carbon wrap.

sch

Presumably aluminum frame? Recent thread about Al frame rear dropout joint to chaintube crack fixed with weld and
"so far so good" after some months but bike was used on trainer only. Welding generally thought of as bad idea because of the loss of
strength and down tube is pretty important in bike integrity. OTOH CF/epoxy wrap and a well prepared tube might
well succeed in salvaging the bike, you would probably lose the WB holder though. Not sure I would want to bomb
an ATB course with such a repair though as it is not clear to me how well the repair would hold up if the tube decided
to bend. This is uncharted territory. Relegated to paved terrain, sub 20 mph speeds and avoiding efforts over 300 watts,
it might last a very long time

Litespud

IIRC the downtube is normally under tension (while the TT and ST are under compression). In this situation, assuming I really wanted to eke some miles out of the frame (as opposed to buying a $150 no-name AL MTB frame and transferring the parts over), I might attach some sort of reinforcement spanning the cut side, and rivet it in place before wrapping. Don't know if it would stop the cut spreading under tension, or if it's even a consideration - tragic to see a frame chopped up like that, though.

delbiker1 

For what it is worth, if that was my bike, that aluminum tubing would already be in the recycle bin.

Bill Kapaun

Is the gene pool self chlorinating?
You have the bike in hand.
We have one semi crappy picture.

dwmckee

Do you have homeowners insurance that would cover you for a replacement? Maybe this plus other damage from the robbery would go over the deductible?

For a wrap like this I'd just use fiberglass matt, doubled, wrapped with aluminum sheet and hose-clamlped until cured. I'd also leave the aluminum wrap in place premanently (less the hose clamps) as it will bond to the epoxy resin nicely. The compression from the wrap will greatly improve the strength of the fiberglass-epoxy. It also could look a lot beter if yiou are neat. I would not try to rivet some metal bridging over the gap as you are adding holes to an already compromised frame. I also say repair at your own risk!

Mad Honk 

If you have filed a police department claim your insurance will cover it. Homeowners policies cover a large amount of $ for damage from theft or break ins. Make sure you have a police report on file. Smiles, MH

xiaoman1 

Op,
I don't think repairing it is feasible....If I were going to attempt a repair I would first drill to small holes on both ends of the cut and then find the appropriate size (exterior dia.) of metal tubing. After cleaning the paint the appropriate amount around the damage I would then split the sleeve in half and epoxy both sides.....sleeve the tube, wrap it with CF, clamp and call it a day....BTW I am not sure I would still be able to give it my full trust/confidence.
Best, Ben

Koyote

Many standard homeowners' policies now have $5000 deductibles, unfortunately.

Even until that policy went into effect with my company, the deductible was $1000 -- which would mean it's not worth making a claim for that bike unless the thief took a bunch of other stuff and/or damaged the doors.

As for the frame: it's a cheapie. I'd just find another one and transfer over the parts.

veganbikes

It is a bikesdirect bike not worth saving in the least and more importantly not worth mega hospital bills for a DIY frame repair that may not go as planned. There are plenty of great bikes in the sea, take this as a sign to get yourself something nice and a little better security on the doors

Plenty of really neat frames. Me I might have some fun on one of those Surly Lowsides or a Vassago Jabberwocky (a frame I should have bought from a co-worker long ago but didn't) Or build out something else. Life is to short for sawed off fauxtobecanes!

drlogik 

I'm with Veganbikes on this. I wouldn't risk life or limb on a frame repair for a major frame compromise like that. It isn't worth it. A catastrophic frame break at the wrong time is not something you want to deal with.

Geepig

Or....

Find yourself a nice sheet of aluminium about a foot long that just wraps around the tube with a slight gap to ensure it is touches the tube fully. Round the corners in a nice steam-punky way.

Weld the cut tube and clean up, or at least drill out the end of the cuts to minimise stress raisers.

Remove the paint for most of the length to be covered by the aluminium.

Mark and drill out suitably spaced holes for riveting.

Apply resin to the frame, wrap with the aluminium, and then wrap that as tightly as possible with strong string so that all the aluminium is covered. Do it in sections, so that later you can uncover one part at a time to drill and rivet it.

Polish and lacquer the aluminium.

Maybe it will no longer be any good on a mountain, but should be fine to go for a coffee somewhere.

_ForceD_

Or...you could completely cut out a section using the crooks initial cut. Save the piece you cut out. Insert something suitable into the down tube...like a smaller tube or a steel bar. Fill the tube with some sort of epoxy to hold it in place. Cut the piece you removed in half. Epoxy it back in place. Then refinish the blemishes. But still...probably better off not relying on the integrity of any repair though.

Dan

ClydeClydeson

Mass-produced aluminum frames like that one are readily available and can be quite cheap. The price for a frame failure while riding a road bike can be quite high. Even in a spot like the middle of the top tube which, as mentioned above, is primarily in compression, a failure on the road can easily result in loss of control and a crash. Maybe insignificant and you get a bit of road rash at the end of your driveway, or maybe you get body slammed in front of a bus.

If you or someone you know is experienced with carbon fiber construction or repair then maybe give it a try, but it's really not worth the risk IMO.

rosefarts

You can probably get something really similar on bike island.

They have bare frames a few years old.

caloso

I would just buy a new frame. The potential of catastrophic failure is too great.

rosefarts

https://bikeisland.com/cgi-bin/BKTK_...0inch%20Wheels

Vintage_Cyclist

motorbacon?

Sounds tasty. Maybe on toast with lettuce and tomato.

Less tasty would be trying to fix that downtube and ending up getting speared somewhere down the road.

Get a new frame and swap over the parts.

Take the old frame, wrap a big sticker around the cut, rebuild with box of crap parts and leave in garage as a quick getaway decoy sacrifice in the event of future crackhead incursions.

WizardOfBoz

It's 6061 aluminum frame. Welding repair is dicey because welding creates a heat affected (weakened) zone that requires heat treating the whole frame to get rid of. The cut is a stress concentrator, and will remain so unless you put a huge wad of CF or other reinforcement. And that CF must be applied and excess epoxy squeezed out properly.

So its a $350 bike. I'd see if I could find a replacement frame or bike. If you find a bike, sell off the parts and scrap the frame.

If you really have to, absolutely must replace it I'd cut all the way through the tube, file and then sand the cut edges absolutely smooth, then sand off all the paint off the tube for about 10 inches. Then I'd see if I could put CF tape on with epoxy, multiple wraps (alternate straight and 45 degrees) with an inflatable collar to squeeze out excess epoxy. Then sand, and repaint. I'd probably want 1/8" thickness. (All gut feel estimates, btw). Is it worth it?

If your question pertained to fixing this with JB Weld putty, epoxy has a tensile strength of about 3500psi. 6061 al has a tensile strength of about 42,000 psi. Plus, the cut slot is just about a perfect stress concentrator. Not sure that you'd be able to make it back even from one ride.

sch

IF I were thinking of the CF route, filling the slot with a piece of sheet aluminum stuck in place would reduce potential
for flex and then a $30-40 CF repair kit from amazon/ebay would be a start. You would want the sheet of aluminum
to be a tight fit in the slot slid in like a CD into a paper sleeve and preferably shaped to the curve of the tube on the
opposite side of the slot on the inside and a bit bigger than the tube on the outside with an extension larger than the
slot to keep it in place. Then as others have said, complete paint removal and probably the WB screw knobs as well
before tight wrapping with CF/epoxy mix. Bike would be ok for casual usage.

FWIW I had a steel frame with 531 tubing that I ran into a curb about 48 yrs ago and bent the top tube and crimped the
down tube just about the DT bosses for the shifters. Welded 2x. Rode it for awhile and one day on a ride about 10-15 miles
out from home the DT snapped completely in half while tooling along on a flat at 15-17 mph. Bike got really springy as
the only thing holding the wheels together was the top tube. I stopped, found some 14 ga electrical wire and attached the
DT to the TT and gingerly rode home. No crash or control loss just a very flexy bike.

Ptcycles

If this a bike you like a lot, here is a solution. I had a similar situation with a Club Fugi that I was very partial to. I have a background in metals and it has worked out well. Looks like the tube isn't even sawed 1/2 way through so here is what I did. Found some scrap aluminum frame material, slightly larger, and cut it about 4 inches long by about 60% of the radius. This way it will kind of snap on when you finish the repair. Remove the paint on the frame in the area of the repair tube part, and remove any paint on the inside of the repair tube, Rough up the the areas where the tubes will touch,( 80 grit sandpaper), wipe down with acetone, buy some gap filling epoxy and glue it up. Lightly clamp, (spring clap), so you don't force out all of the epoxy, and cleanup with acetone. Will not be too obvious and by not covering the whole tube you can monitor whether the tube will possibly crack. Mine has been this way for 5 years and no problem. Good luck.