Is it time to retire the trusty steed?

[elronino]

So, I recently took a trip to Arizona for some end of the year riding. Had a so so trip, but this just really capped it off after a long weekend. Thoughts on integrity of the frame and if I should continue to ride/race it. I am 200-205 lbs and don't tread lightly...

 

[Volnix]

Maybe its a good idea to send this to the factory through the LBS and see what they say about it...

How did that happen???

 

[CAMPYBOB]

Meh...it's now perfect for crits and roadraces full of freshly upgraded dweebs.

Put the good set of wheels on it and flog it into the turns with a ****-eating grin on your face.

Bar slap?

 

[David Gerchman]

Good excuse to buy a new frame becuase it isint pretty anymore? YES!!
Good reason to buy a new frame becuase its unsafe. NO!
If you are that worried about it, replace the top tube. Not that difficult on a metal bike.

 

[Volnix]

Originally Posted by David Gerchman .

Good excuse to buy a new frame becuase it isint pretty anymore? YES!!
Good reason to buy a new frame becuase its unsafe. NO!
If you are that worried about it, replace the top tube. Not that difficult on a metal bike.

I read somewhere that aluminium frames are not very repairable, it looks pretty unsafe... Its not just a scratch the thing is dented, it might brake apart after a knock on something.

What does the manufacturer say?

 

[CAMPYBOB]

"I read somewhere that aluminium frames are not very repairable,..."

They are and they aren't. Cost being the main reason. It is less expensive to buy a new aluminum frame than to repair a damaged one and deal with the metallurgical issues of the heat affected weld zone, alignment, etc. A decent Al frame is what? Around $200-$400? That doesn't buy much shop time/skilled labor. We repair structural Al aircraft parts. They cost/life cycle analysis being a completely different animal in that case.

A dent, such as the one pictured, will affect the tube's ability to carry load, but used as a race beater and keeping an eye on the area (failure mode of aluminum usually gives a warning period with stress fracture/crack propagation)...I would use and abuse it like a cheap suit. As always, YMMV.


"What does the manufacturer say?"

Best idea so far. Contact Trek. They may discount a replacement frameset.


Anyone remember "The Good Ol' Days"â„¢? If that were a steel Reynolds or Colombus tubed racing bike, the paint would be sanded off for a few inches and the tube rolled in a pair of wood blocks in the bench vise...no more dent. A little more sanding and a coat of spot-in paint and it's good for another five years!

 

[David Gerchman]

Um... Its metal. With a good filler and a tig welder and good atmospheric control there is no reason why you cant replace the tube. If you have a monkey who can't weld without heating the hell out of the surrounding material, then you replace the frame. If you are worried about the structural integrity of the frame then normalize it in a oven. Now granted these maybe fab skills that are beyond the average bike rider, but not impossible. Aside from needing to be repainted the labor shouldnt take more than an hour or so. $75.00 for a new powdercoat and your set. you will just lose the factory decals.

 

[Volnix]

Originally Posted by David Gerchman .

Um... Its metal. With a good filler and a tig welder and good atmospheric control there is no reason why you cant replace the tube. If you have a monkey who can't weld without heating the hell out of the surrounding material, then you replace the frame. If you are worried about the structural integrity of the frame then normalize it in a oven. Now granted these maybe fab skills that are beyond the average bike rider, but not impossible. Aside from needing to be repainted the labor shouldnt take more than an hour or so. $75.00 for a new powdercoat and your set. you will just lose the factory decals.

In that case... I would recommend this guy: /img/vbsmilies/smilies/biggrin.gif

 

[dhk2]

Originally Posted by David Gerchman .

Um... Its metal. With a good filler and a tig welder and good atmospheric control there is no reason why you cant replace the tube. If you have a monkey who can't weld without heating the hell out of the surrounding material, then you replace the frame. If you are worried about the structural integrity of the frame then normalize it in a oven. Now granted these maybe fab skills that are beyond the average bike rider, but not impossible. Aside from needing to be repainted the labor shouldnt take more than an hour or so. $75.00 for a new powdercoat and your set. you will just lose the factory decals.

David, I'm skeptical that a replacement of the top tube could be done in an hour, or even that a skilled framebuilder would want the job. Maybe we're talking about different repairs here; could you outline the steps you envision in the repair and how long each would take? If this was your bike, where would you take it for repair?

 

[danfoz]

I would charge this thing to the finish line among the throws of blood curdling and demonic laughter and watch the CF boys clear the sea before me. After checking with the manufacturer I'd actually probably just pick up a replacement. Cheap alu frames can be had for a few hundred, go up to $700-800 and you can choose from among the best alu out there. Among them the Specialized Allez and Cinelli Experience. Sadly many manufactures do nor sell their alu frames separately (like Trek and C'Dale). There are also all kinds of surplus alu frames available form euro manufacturers like Guerciotti and Ciocc available on the internet. Personally I would be fine riding the bike all the while keeping attention to any additional damage that might occur i.e cracks etc, but I prefer a clean bike. YMMV.

 

[dhk2]

Agree with CB and danfoz here. I'd ride the bike as well, keeping an eye on the dented area for any cracking and not worry about the appearance. As an old cycling buddy once told me when I commented about his dirty bike " it's a tool, not a jewel".

 

[CAMPYBOB]

"I would charge this thing to the finish line among the throws of blood curdling and demonic laughter and watch the CF boys clear the sea before me."

I find myself spitting coffee and mentally picturing Madone7.x series and $5,000 Pinarellos rapidly moving offline and a brilliant white light emanating from a rapidly closing finish line. /img/vbsmilies/smilies/biggrin.gif

Be afraid of the guy on the starting line with scabs on his legs and a dented frame. Be very afraid!

 

[David Gerchman]

Originally Posted by dhk2 .

David, I'm skeptical that a replacement of the top tube could be done in an hour, or even that a skilled framebuilder would want the job. Maybe we're talking about different repairs here; could you outline the steps you envision in the repair and how long each would take? If this was your bike, where would you take it for repair?

I would repair it myself if it was mine. the time it takes to do the repair has a direct correlation with how many tubes the repair guy has notched and fit. I come from a circle track world(read racecars not velo's) I have notched so many tubes I don't even want to think of a number. As long as you know the 2 tube angles and can maintain them your golden. building suff from tubular metal is really alot simpler than most people think. Ti gets goofy without enough argon, and alum has to be cleaner than chromo. Just quirks of the metals.-David

 

[Pat Stowe]

ride it till it starts to crack, which may never happen before it fails elsewhere or you get tired oof it. You might find someone who has a tool to "suck out" the dent, but keep in mind aluminum weakens when bent, Iv'e seen a lotta bikes with similar dents go fine for years

 

[dhk2]

Originally Posted by David Gerchman .

I would repair it myself if it was mine. the time it takes to do the repair has a direct correlation with how many tubes the repair guy has notched and fit. I come from a circle track world(read racecars not velo's) I have notched so many tubes I don't even want to think of a number. As long as you know the 2 tube angles and can maintain them your golden. building suff from tubular metal is really alot simpler than most people think. Ti gets goofy without enough argon, and alum has to be cleaner than chromo. Just quirks of the metals.-David

OK, that would explain your confidence here. People used to talk about repairing the old-school lugged steel brazed or silver-soldered frames, but I've never heard anyone say it's worth replacing a tube on a lugless frame before. Curious, what kind of machine or tool does it take to notch the tubes, and how close do the joint lines need to be for a strong weld? I idea of cutting the radius of the headtube out of the end of a shaped top tube, on the correct angle, seems very difficult to me.

 

[CAMPYBOB]

"Curious, what kind of machine or tool does it take to notch the tubes, and how close do the joint lines need to be for a strong weld?"

I use a Bridgeport or Gorton vertical mill and set the angle with a sine plate/Jo blocks. A compound sine plate is required for some tube joints.

Getting the miter to within .015" would be no issue and plenty close for welding. As Dave stated, the Al must be perfectly clean and free of grease, oil or other contaminents or you're going to get a lot of sputters and possible inclusions.

 

[Volnix]

Maybe you could also just remove the part that is dented so it wont further spread the bent to the rest of the tube whilst using the bike and insert something else in there like they did on that frame:



There are tubes which have holes on them for running internal cable routing etc. But they are usually just a few mm in diameter. They are also cut with the correct tools I suppose so no new cracks starts from the hole. In this case there is another cf tube inside the titanium grid-tube, so maybe another idea would be to cut the dented area, and insert a tube inside the tube and somehow secure it there with some bolts, or an outer tube made of two half-tubes connected and again bolted on the tube. Another idea would be to cut the whole tube lentgh in the affected area and connect it again with a flange or something like they do in folding bikes.

But the main problem would probably be that this looks like a hydroformed butted tube. Since the thicknesses of the tube and the shape are not symmetrical, making a repair like that would probably change the load transfer somehow and possibly create more weak spots. Finding a correct flange or tube that fits could also be difficult.

Its probably a good idea to avoid all types of welding done in a place other then the original factory which probably uses ultra-sonic testing for their welds. They also know the exact type of alloy they use for their bikes and the correct temperatures for welding, curing it etc... They will probably have some information for situations like that.

 

[dhk2]

CB, sounds like the precise way to do it. Assume the cutting tool has an adjustable head so you can match the OD of the headtube or seat tube exactly? As you can tell, I'm no machinist.

I found a YouTube video of a guy who was working on heavy steel tubing 2 or 3 inches dia with a marking pen and disc grinder....figured there had to be a better way for thin-wall tubing which is often not round in profile.

 

[CAMPYBOB]

"Assume the cutting tool has an adjustable head so you can match the OD of the headtube or seat tube exactly?"

Usually, I can find a cutter diamter to match the mating tube...end mill, hog mill, shell mill, etc. If not, a mill cutter with carbide insert bar. The bar has an adjustable swing radius. Plunge cut as required.

Fly cutter tool holder, not shown is the cutting tool that fits in the slot:



If high precision is required or a machine is open, I can CNC mill the required radius or wire EDM it.

 

[dhk2]

Got it, thanks for reply and photo.