I am planning my first cross-country tour and bought a Trek 614 bike off of eBay to restore. Its been sitting awhile and this weekend I began to work on it when I noticed that the frame appears a bit bent. The top tube near the head tube seems to curve slightly down. I used a straightedge conformed that it is bowed a little. See attached pictures. Its very slight, I didn't even notice it at first. The frame everywhere else seems to be in good condition. Could this slight bend compromise the frame's strength? Would I be better off getting a new frame for the build? Thanks in advance for your input!
if it didn't come with a fork, it suffered a frontal impact. Of course, given your measurement, it probably suffered a frontal impact. I am not familiar with the 600 models of that time period, but when I made them they were pretty light for a loaded touring bike. Not sure what to tell you about yours, I probably wouldn't use it, if for no other reason than the geometry is bound to be a little messed up.
Stewart S&S coupled sport tourer, Stewart Sunday light, Stewart Commuting, Stewart Touring, Co Motion Tandem, Stewart 3-Spd, Stewart Track, Fuji Finest, Raleigh Pro, Trek Cycle Cross, Mongoose tomac ATB, GT Bravado ATB, JCP Folder
It's hard to see the TT droop you mention. Perhaps a shot with the straight edge placed on the tune to see the gap? Also how's the DT and fork? There doesn't look to be any buckling so I doubt any structural issues exist. If the bike had a directly frontal impact there should be no twist to the HT and only a rearward bending. Sighting along the HT and ST might indicate any twist. If the head angle was moved back due to an impact then the steering geometry has changed. Whether it's changed much and to the negative with a loaded bike a test ride will give the truest finding. Also the fork might have been bent in an impact. Fork twist is easy to spot with a couple of straight edges. Side to side off centering a bit harder but a good wheel and sighting down along the steerer past the mounted wheel can bring out this potential. The fork's possibly being bent back is best looked for by supporting the steer off a surface with the blades curving up and then rotate the fork with the blades curving down (and hanging off the surface edge). Measuring up from the surface to the blades' point before thety start to curve should be the same both ways the fork is set.
How any slight bend/misalignment effects the ride/stability is a tricky thing until you test a built up bike with touring weight loaded. I have known a few bikes with slight impacts that improved their stability and many that negatively changed things.
But don't think that the bike was built with perfectly straight tubes, or the after brazed up frame had straight tubes after aligning was done at the factory. Measure to understand but test to be sure of real world results. Andy.
unfortunately, that doesn't mean anything. Missing fork tells the whole story.
There is only one way to get a curve in the top tube like that: frontal impact. It can often be hard to tell what is up with the downtube. Assuming it handles ok, there probably isn't anything wrong in riding it, but I wouldn't do it myself.
on edit: what Andy says is true, steel tubes are all bent to some degree, but I'm almost certain I can see it so it's not normal.
i can't see any bend from looking at the pics. and the OP says the frame came with the original fork. i guess it's just not in the picture? so i'd measure it again. or get your brother-in-law to measure it. they are ALWAyS wrong, so if he says it's good to go, you can just pitch it...
Thanks for all the responses. It is hard to see the bend in the pictures I provided. Ill try to get a pic with a straight edge tomorrow. The fork doesn't appear to be bent at all but maybe Ill take them down to the LBS and have them check it out.
There may be a slight bend, but my guess is that if the tubes are not kinked and still of a cylindrical cross-section (round, not ovalled) all the way across, there's minimal fatigue that's occurred. To detect kinks, your fingers are probably more sensitive than your eye.