Cracked dropout and bent stays, worth repairing and how?
To those inclined against reading a stranger's mushy maundering, my question is three paragraphs down.
I've been sitting on what to do about my broken bicycle and I thought it might be good to crowdsource this one. My beloved Peugeot PFN-10E broke at the very end of the right chainstay. This is the second time I've had a frame fail, and in the same place no less. The first was repaired with new dropouts from Ceeway in as slipshod a manner as may be possible. Basically involved a lot of wishing and hoping that I chose the correct brazing rod out of the Fred Meyer variety pack and watching my father try not to cook the Tange Ultimate Superlight steel while using, cough, a rosebud tip. Good times. Yes, it's held up so far.
Flash forward to the present, and now through buddy I have access to proper brazing rods and flux, and #2 and #4 brazing tips. So order up a new set of dropouts and braze them doggies in right, right? Problem: if you'll look at my photo, you can see that the stays are bent up a few degrees right where the dropout tabs end inside the stays. In my photo this is most visible on the left seatstay, but they are all bent this way. Possibly from when I accidentally went over a curb. I weigh 200lbs, and this is a fairly lightweight chromoly frame. Hell, it's also got a slightly bowed top tube from when I hit a parking lot car stop at 3mph. Didn't even put a foot down before moving on. And it wasn't the most exquisitely built to begin with; the seatstay cluster is misaligned, the chain and seat bridges are askew, this is genuine French manufacture here, to be sure. Soooo, maybe not worth repairing, except I absolutely love this bike. The ride is sublime, and it has a lot of sentimental value. It was my first high quality bike (despite being a couple years older than me!), and the one I learned to wrench on.
I want to put this bike back on the road, just not sure how big of a problem those bent stays are. The bike has been fixed for a while now, not planning on putting gears back on, and since I don't run a rear brake, I was thinking track ends could work. Idea being that I find a set of flat plate track ends long enough that I could just cut the bent part of the stays clean off, file in a new set of slots, and braze it up nice and fresh. Anyone know of a set of track ends with arms long enough to do this? Might the ones from Nova work? (they DO call 'em larges) Think the bends aren't a big deal and I should just braze in whatever? What have you?
Wow....amazing that held all this time, huh?
To answer your question, Henry James has the only track ends that I know of that are designed to replace drops and have long tabs to accommodate this. Keep in mind that you'll have to keep the axle slot at the same height as the original.
However, I think you have much larger problems here my friend- the reason your stays bent like that is probably because your Pop overheated the snot out of them and they are nice and annealed- meaning the ends of the stays are soft and weak.
To give this job a possibility of success, you'd want to cut off and inch or two from both sets of stays- then you'd need a drop with really long tabs. I say get a sheet of 3/16"- 1/4" 4130 and make some. It's not that hard and it will allow you to get pretty creative with the design. You could even use mild steel, but I'd prefer the extra stength of the 4130.
it's time for recycling, R.I.P. (rest in pieces)
If your going to make your own just keep in mind that 4130 sheet is getting really tricky to find
Live Wire, your analysis of why my stays are bent could not possibly be correct, because it was an entirely different bicycle (the Barracuda in back of the photo) which was repaired the first time! Surely no need to cut two inches off, still think it's essential that I cut any at all? It's only about 1/2" that's bent, and again, NOT annealed; work hardened. I've already got two pieces of 3"x3"x1/4" 1018, a cross-slide vise and a couple end mills, so I could probably etch-a-sketch myself up some custom dropouts. Otherwise, those Henry James conversion track ends might just be the ticket. Thanks for the replies, guys.
Last edited by Thasiet; 09-06-08 at 09:02 AM.
So the pic you put in the op isn't a pic of the bike in question? Not following you on that point.
Originally Posted by Thasiet
Still, if you were able to bend your seatstays by riding off of a curb, there is a real weakness there- and the steel on an old Pug wouldn't work harden by being overheated with a torch.
Do what you want, whatever the result, it will be a good learning experience and you have nothing to lose.
Ok dude, you're trying to help me, and I appreciate that, but you're not getting it. I have had TWO COMPLETELY DIFFERENT BICYCLES break at the dropout. The first was a Barracuda A2E 1996 hardtail mountain bike. This is the one that was repaired with the rosebud. It is in the BACK of my photo, as I said. The Peugeot is the bike I am asking about. It is the bike in the front of the photo. I understand that flames do not work harden tubes, but the Peugeot has not seen a flame since leaving the factory. The Barracuda saw a flame. The Peugeot has not seen a flame. I understand that tubes are work hardened by bending them, and the tubes on my Peugeot are bent (the dropout is also cracked). My assumption then that a little bend in the tubes maybe isn't a big deal, because the tubes are stronger now. Correct? Incorrect? I don't know if they were bent by going off a curb, that was just a hypothesis. I don't know how they got bent.
I wouldn't have the first bit of hesitation repairing that frame by slapping a new dropout in there. But what are you doing to break dropouts?
Unterhausen, dude, I must just have terrible luck. I know the right chainstay-dropout joint is the single most common place for a frame to fail, due to cumulative fatigue from the torque of the drivetrain, but still, twice already? I hadn't ridden the Barracuda much prior to it happening, and it came to me in pretty well ridden into the ground condition, so I'll blame that one on the former owner. As for my Peug, well, I rode it fixed-gear, I rode it like stink, and the frame may well be a little too race-weight for my 200lbs (but oh is it ever supple). I definitely want to repair it, but will probably go the cheap route and make my own dropouts out of the 3"x3"x1/4" 1018 plates I've already got. I put them up against the dropout and it looks like I have enough metal that I can trim back the bent parts on the chainstays, but not the seatstays. Think that'll be a problem?
Originally Posted by Thasiet
Oops, I missed your reply.
K, I guess I read the op too quickly because I didn't see that you were talking about two broken bikes- I get an "F" for comprehension.
The bent tube thing is a concern because there's no way it should have happened from curb hopping and it will make aligning the new drops problematic. Maybe they bent when the drop broke?
Still, it's a worthwhile learning project- so break out the torch!
Yeah somehow in my screed I completely forgot to mention that I rode about three miles home on the cracked dropout... that could pretty easily be how the stays got bent. Sounds like it shouldn't be an issue as far as strength is concerned. I'll cut away as much as I can and will keep in mind alignment when filing everything. Alignment doesn't seem critical though, since I don't have a rear brake to line up with.
I would cut away the minimum possible from the stays. Remove all of the old dropout. From the picture, it doesn't look like anything buckled, just bend it back.
Finally got around to it.
Anyone want to confirm that the liquation of the copper out of the brass is actually the liquation of the lower melting point zinc into the brass that remains, and that this was caused by my holding the rod too close to the frame before it was hot enough?
Anyone want to give me odds that this guy will hold? It has for 75 miles already.
This was an intriguing thread. Looks pretty good and I am betting it holds.
If I remember correctly, with a brass brazing rod the zinc melts out first when the temp isn't hot enough to melt the copper as well. A joint brazed with just zinc will stick, but will be much weaker than one made with the brass alloy. No problem if you continued to heat such that the copper got a chance to melt in as well, though.
And for reference purposes - McMaster-Carr sells up to 1/4" plates of 4130 steel online.
What would be the advantage of using 4130 for the dropouts vs mild steel? Dropouts should be malleable, after all.
Originally Posted by dods1600