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-   -   Deep Sigh (https://www.bikeforums.net/classic-vintage/1248920-deep-sigh.html)

BTinNYC 03-24-22 09:17 AM

Deep Sigh
 
https://cimg5.ibsrv.net/gimg/bikefor...cd477cfdac.jpg
Finished the 3 month Centurion Prestige build. Adjusted everything on the stand. Test rode up and down the block, brifters and brakes, it's working nicely so I go to end of the block, turn left uphill and stand on the pedals. I didn't finish the second rotation when it came apart violently.

This was a tough lesson; when building on an old frame with unknown history, build and test before any cosmetic work.

Only 10 minutes to live
https://cimg0.ibsrv.net/gimg/bikefor...e7433ae5c0.jpg

So, the worst has happened; n-1, and this will be rectified soon!

3speedslow 03-24-22 09:21 AM

What a shock!

smd4 03-24-22 09:40 AM

Ugh. I feel your pain! I've never seen a failure like that. I wonder what kind of forces, and in what direction(s), caused such a failure.

Bad Lag 03-24-22 09:46 AM

Get it fixed. It will be worth it.

SwimmerMike 03-24-22 09:47 AM

Holy crap, never seen that before. Hopefully you came out of it unscathed.

BTinNYC 03-24-22 09:50 AM


Originally Posted by smd4 (Post 22449389)
Ugh. I feel your pain! I've never seen a failure like that. I wonder what kind of forces, and in what direction(s), caused such a failure.

My guess is the dropout had been bent back and forth in its life and was weakened at the thinnest section, at the threaded hole.

poprad 03-24-22 09:52 AM


Originally Posted by Bad Lag (Post 22449396)
Get it fixed. It will be worth it.

Definitely. A good frame guy can braze you in a new dropout for not much drama, and the repaint for that section only shouldn't bee that pricey either. That's too gorgeous a build to abandon.

BTinNYC 03-24-22 10:02 AM


Originally Posted by SurferRosa (Post 22449406)
Nah. What happened there is an anomaly.

Glad to read that.

jrg1244 03-24-22 10:18 AM

Awful... Though the half a dropout is proof positive of the enormous wattage that you clearly put out. If it were mine, I'd hang it on the wall and recount the story to houseguests. Good luck finding your n+1!

smd4 03-24-22 10:25 AM


Originally Posted by BTinNYC (Post 22449401)
My guess is the dropout had been bent back and forth in its life and was weakened at the thinnest section, at the threaded hole.

I would think the force exerted would tend to pull the axle towards the front of the dropout, along the slot. What caused it to force the bottom part of the dropout (I'm guessing), down, vertically?

JohnDThompson 03-24-22 10:39 AM


Originally Posted by smd4 (Post 22449443)
I would think the force exerted would tend to pull the axle towards the front of the dropout, along the slot. What caused it to force the bottom part of the dropout (I'm guessing), down, vertically?

Usually it happens as a result of the chain jamming and pulling on the derailleur. This could have happened under a previous owner, who straightened the damage. A subsequent hard shift may have been enough to cause the failure in that previously weakened spot.

Rage 03-24-22 10:42 AM

That build came out pretty nifty. Sorry that happened.

smd4 03-24-22 10:43 AM

Well, all the old books say that a great benefit of steel frames is that they can be relatively easily/cheaply repaired. Time to place that ancient wisdom into practice!

bamboobike4 03-24-22 11:17 AM


Originally Posted by jrg1244 (Post 22449435)
Awful... Though the half a dropout is proof positive of the enormous wattage that you clearly put out. If it were mine, I'd hang it on the wall and recount the story to houseguests. Good luck finding your n+1!

1. Likely bent in shipping and bent back.
2. Worth fixing.
3. Take the picture, frame it, mount that on the wall as proof of your wattage.
4. Refine the story to generate swoonage.

scarlson 03-24-22 06:36 PM

Long drive, but...
Come to Harvard and I'll MIG it for you.
Bring a nice Calvados or green chartreuse and be prepared for an evening of fun.
My prior dropout work is here. I'm confident I can do this. Super easy, especially if you can forego the adjuster. I can redrill and tap the adjuster as well, just a bit more work.

;)

BTinNYC 03-24-22 06:47 PM


Originally Posted by scarlson (Post 22450021)
Long drive, but...
Come to Harvard and I'll MIG it for you.
Bring a nice Calvados or green chartreuse and be prepared for an evening of fun.
My prior dropout work is here. I'm confident I can do this. Super easy, especially if you can forego the adjuster. I can redrill and tap the adjuster as well, just a bit more work.

;)

You would weld the two parts together?

scarlson 03-24-22 07:03 PM


Originally Posted by BTinNYC (Post 22450030)
You would weld the two parts together?

Sure I would. For a bottle of green chartreuse and some agreeable company. Would also consider aņejo mezcal or tequila. You know, the stuff that's been aged on oak. Come over on the megabus, tell them it's a folding bike, they won't know!

I'd rather do that than try to source another dropout, melt and grind and file the old one out, prep everything, and braze it. The bottom of the dropout doesn't see much stress. This is way easier than the one I just did, linked to above. Only risky thing is trying to drill through the weld and tapping that hole for the adjuster. Much easier and stronger if you forego the adjuster on that side. But I can drill it too, if you must.

John E 03-24-22 07:09 PM

This is the one argument in favor of stamped dropouts over forged.

It is also possible that the dropouts were not properly aligned, or that the previous owner had broken a rear axle and stressed the drive side dropout in the process.

thumpism 03-24-22 09:14 PM


Originally Posted by jrg1244 (Post 22449435)
Awful... Though the half a dropout is proof positive of the enormous wattage that you clearly put out. If it were mine, I'd hang it on the wall and recount the story to houseguests. !

"...so there I was, rolling easily along at about 8/10ths when I decided to pour on the coal..." Etc., etc.

canklecat 03-25-22 01:32 AM

Any signs of corrosion in the threads of the adjuster hole? Just grasping at straws here.

That's gonna be a pretty build once it's back together.

plonz 03-25-22 04:13 AM


Originally Posted by scarlson (Post 22450041)
Sure I would. For a bottle of green chartreuse and some agreeable company. Would also consider aņejo mezcal or tequila...

Sam, a welder and tequila... what could possibly go wrong!

OTS 03-25-22 04:44 AM


Originally Posted by plonz (Post 22450260)
Sam, a welder and tequila... what could possibly go wrong!

Hahahahahahaha
Good one ! :roflmao:

nomadmax 03-25-22 05:19 AM


Originally Posted by smd4 (Post 22449389)
Ugh. I feel your pain! I've never seen a failure like that. I wonder what kind of forces, and in what direction(s), caused such a failure.

I've seen that before. In those cases, it was from putting a longer OLD axle in frame designed for 120/126mm without cold setting and making sure the dropout faces were parallel to each other. Mind you, that's not what I'm saying is the case here.

BTinNYC 03-25-22 07:28 AM


Originally Posted by nomadmax (Post 22450285)
I've seen that before. In those cases, it was from putting a longer OLD axle in frame designed for 120/126mm without cold setting and making sure the dropout faces were parallel to each other. Mind you, that's not what I'm saying is the case here.

Hmmm. I wonder.

I will very closely check the DOs after fixing.

I did not successfully cold set because the stays were like spring steel (wouldn't hold a mm of bend, even after spreading to 165mm, yet relatively easy to spread by hand) and now my check for parallel with a homemade tool feels cursory.

Edit PS
Wouldn't that misalignment become evident while setting up the RD?

swampyankee2 03-25-22 07:37 AM

I'd get that MIG or TIG welded for sure. As said, welding would fill in the tapped hole, but it could be drilled out and tapped after. If MIT is too far, maybe someone at RPI?


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