Rik90

Hi,
I have recently purchased a used bicycle. It is a custom-built but the frame is a 2017 Émonda ALR 4. I noticed that there is an unusual bump on the bottom of the down tube, close to the fork (basically in the middle of the K of TREK logo on the downtube). The bump is very symmetrical so I was wondering if it is actually a welding point, but it looks like there shouldn't be welding there.
Let me know what you think.
Thanks in advance.
R.

squirtdad

need pics

pure speculation without a pic, but is sounds similar to what you see if a bike hit's something head on and there is some bending. look at the top tube hear the headset and see what you see

jimc101

What about asking the person you got it from? probably something to have checked before purchase.

With no photos, anything is a guess, have you thought about taking it to a Trek dealer, even though the model is 3 years old now, they should have some knowledge of if the bump is a manufacturing mark or defect due to damage

Andrew R Stewart 

The "K" is pretty far from the usual location for a head end impact tube ripple. Andy (who is shooting in the dark without imagery)

WizardOfBoz

Trek claims that this bike is built with "invisible weld technology" so I'd suspect that its not a factory weld. Also, I'm with Andy - I would think any welding would have been closer to the head tube than the "K" in Trek. The stock pictures of ALRs show a pretty straight downtube. Put a ruler or straightedge up to it on top and bottom to see if the tube surfaces are straight?

Rik90

That's what I thought after reading a bit online. I would love to post pictures but the forum doesn't let me do it as I recently registered.

Rik90

I tried the ruler thing and all looks straight on the top of the top tube and on the top of the bottom tube. The bottom part is curved by design so the ruler test wouldn't work there. I also suspect is most probably not a welding but it is also very hard to think that the frame bent in such location due to a frontal impact. Fork is perfectly fine and everything else as well.

Rik90

It all looks pretty good to me. There is another small dent on the top tube but it is not where the handlebar would normally hit in case of a frontal crash. Any specific advice on how to check the headset? Thanks

Andrew R Stewart 

Does the fork/bars freely swing to either side when the bike's front wheel is a couple of inches off the road and the bike is slightly leaned to one side? Does the fork/bars seem to settle into one position if pointing forward? With the bike on the road and locking the front brake on can you rock the bike fore and aft and feel for any knocking/slop between the headtube and the fork/stem? Has anyone yet taken apart the headset? Andy

WizardOfBoz

Rik, if you can upload a pic to imgur or google photos, I think (could be wrong) you can include the URL in a post.

But you're only 6 posts (IIRC) from being able to post photos directly.

BTW, is the paint in the area you are referring to smooth? Wrinkled? Cracked? If its smooth paint, and your tubes are straight, it may just be that Trek's "invisible welding" wasn't so invisible. The hand-brazed Schwinns ("fillet brazed") were pretty well finished where you could see the results, but the bottom of the bottom brackets were not as nicely smoothed out. May just be that they left a weld bump on the frame.

Rik90

Would this work? imgur.com/9XFkn03 imgur.com/pNcIsos

WizardOfBoz

Rik, these look like small manufacturing aberrations to me. Especially if the fork is ok. Perhaps others can comment(there's guys commenting in this thread who build frames and who have more and better expertise)? As a final resort, you could contact Trek and ask them. But I think you're ok.

Brocephus

Yes, definitely contact Trek. I've found they're quick to get back to you.
Also, in the first of the two pics above, I felt like the tube had a bend in it, at the point of the "bump". So I grabbed a sheet of typing paper, holding it up to the pic on the screen here, and using the straight edge of it, held it along the edge of the tube both in front, and to the rear of the bump, and compared to the edges of the tube on the opposite side. There seem to be two different angles here, as though the tube bent a tiny bit, and the bump is the excess material protruding outward from the point of the bend.

WizardOfBoz

Rik,

There are wizards with paint, but I think that the paint looks original. If so, you are correct. Also if so, I don't see this as a problem: the frames are welded on fixtures that hold them to tight tolerances in actual geometry. But my experience with Trek is also pretty good. Ask 'em and see what they say.

If it was my bike, I'd ride it without a worry.

The Wiz

Spoonrobot 

I’d be amazed if that was anything other than a hard front end impact that rippled the tube. If that was something I found without context on a used bike I wouldn’t ride it. IMO both the fork and frame are suspect - especially the fork.

Carbon forks are strong enough in front end impacts that often the frame will fail instead of the fork at the time of impact. The fork will then last an indeterminate time until it also fails JRA.

If anything you should measure the angles, an alignment table should have the granularity to show the changes to the headtube angle. Or even the wheel base. It doesn’t take much.

squirtdad

that is sure what it looks like to me....location is a bit different than what it would be on a lugged steel bike.... but bump/deformation top and bottom tube indicates this. certainly not how it came from the factory (based on googling some pics)

WizardOfBoz

With the top and bottom tube straight, and the fork good, I'd think that this would be mfg. But you have others with perhaps more expertise suggesting a crash.

To differentiate, there's another couple tests: measure the front axle to rear axle distance. Compare this to distance J in the figure below (which is supposedly from a 2017 Emonda ALR 5). Or you could look at the headset angle. I have a machinist's protractor, but I have no idea how I'd jig it up to measure head angle. But that would be sensitive. Another sensitive measurement, not shown on the diagram, would be to measure the distance between the down tube and the tire, or (because wheels and tires vary) the downtube and the front axle. This latter test would require another 2017 Emonda ALR 5 owner with the same size bike (or Trek) to step up and tell you what they have on their bike. Contrary to Spoonrobot's (reasonable) assumption, the one measurement ("J") we want is not provided in mm granularity.

One picture that might help would be that of the bike on level ground with the fork pointed straight ahead. If the tire/downtube clearance looked hinky, this would be a clue.

HTupolev

There definitely is not welding there. I have a similar frame (a 2016 Emonda ALR), and the welds are visible and where you'd expect them to be.

Ripples like that on the bottom of the top and down tubes near the head tube joints usually indicate damage from a front-end collision.
Such a collision does not necessarily result in obvious damage elsewhere. For example, oftentimes the front tire will not suffer a pinch flat, and the front wheel will not go out of true.

grizzly59

Get a magnifier and start looking for cracks in the paint. Especially around the bottom of the head tube, and around the down tube where it meets the head tube. Check around each fork blade where it meets the crown. Look at the where the lower cup of the headset fits into the head tube. I would take the fork off and look all around where the steerer meets the crown, looking for anything bent or cracked. With the fork out, check to see if the lower cup is loose, crooked, etc. Look around the top tube where it goes into the head tube as well. If everything is symmetrical and no evidence of bends or cracks, you might be okay. If the down tube is bent, you should be able to find some other evidence showing on the frame or fork if you really look.

02Giant 

I would contact Trek, doesn't look right.

Mad Honk 

Rik,
From the pics I would tell you that this frame has been in a crash. The bend is just below where the aluminium tube was spec'ed out thicker for the welds, or near a butting section in the tube design. Trek likely didn't warranty it for the original buyer so he sold it off and got a new one. My estimate is that you bought a good donor bike for a new frame and a complete change over is in order. JM2cents worth. MH

Rik90

Thanks. Are you saying that you think this frame is not safe to ride?

Trevtassie

I wouldn't....

Spoonrobot 

I'm more concerned about the fork but I would not ride the frame either. I've had 4 frames crack while riding, so my patience for a (potentially) damaged frame is very low. There also appears to be a front brake divot so the bike has not been handled very well.

See what Trek says and see if you can get your money back.

Rik90

The fork is perfectly fine, not even a single scratch. But, know knows, maybe it was replaced. Why would you say the frame is damaged? I can't see any visible crack on the wrinkled spot. I noticed the brake divot, and that's also a potential sign for a frontal crash.