Crimped Seat Tube and Wonky Cassette

[bahnbrenner]

Hi Everyone,

Today, during the course of a routine cleaning I discovered (to my horror) that my front derailleur adapter clamp has crimped the steel of my seat tube. Someone installed the front der. for me, and I was a complete idiot for letting them even come close to my bike. At any rate, the damage is done and I am wondering if it can be fixed, and if so, if it is worth fixing.

Also, for some reason, my cassette is having problems. It is a Campy 9 speed unit converted to an 8 speed. I simply dropped the largest cog and added a titanium Record spacer (which worked perfectly). It looks as if the hub is broken or something, because the cassette rotates out of alignment. Imagine a wheel with a hop, and that is what the cassette is doing.

Just a bit of background, its a fresh build of a Club Special that I have only been riding for about three weeks.

Any ideas?


Thanks for the help!

Austen

[Louis]

Bummer. Structurally, I doubt the local "crimping" will cause buckling or anything like that, so as long as the F-der still shifts properly the only issue is the long-term effects on the metal right at the clamp.

I would guess that you're probably fine. Is the paint cracked? That might lead to premature corrosion, but that's about worst thing I can think of. If that's the case it may need to be addressed.

Years ago I had a relatively bad head-on with the side of a truck while riding my old steel Trek. I just bent the fork back (the wheel couldn't pass under the DT, rode it for a few years, then replaced the fork. I knew that there was damage at the TT and DT just behind the HT lugs (bent metal and cracked paint) and eventually the DT failed right at the shifter bosses. That was probably way way worse than what happened to the metal in your case.

Good Luck

[HenryA]

Its probably just the paint. Gnarled up paint can look bad but not be a structural problem. Crushing the downtube with a derailleur clamp would be pretty hard to do -- think about it.

[oldpotatoe]

Hi Everyone,

Today, during the course of a routine cleaning I discovered (to my horror) that my front derailleur adapter clamp has crimped the steel of my seat tube. Someone installed the front der. for me, and I was a complete idiot for letting them even come close to my bike. At any rate, the damage is done and I am wondering if it can be fixed, and if so, if it is worth fixing.

Also, for some reason, my cassette is having problems. It is a Campy 9 speed unit converted to an 8 speed. I simply dropped the largest cog and added a titanium Record spacer (which worked perfectly). It looks as if the hub is broken or something, because the cassette rotates out of alignment. Imagine a wheel with a hop, and that is what the cassette is doing.

Just a bit of background, its a fresh build of a Club Special that I have only been riding for about three weeks.

Any ideas?


Thanks for the help!

Austen

Might have a split freehub body, pretty common on earlier, aluminum axled Campagnolo hubs or at least the axle end is loose(tightens lefty tighty-left threading).

If so, the fix used to be a freehub body but the older ones are gone, you can still replace the FH body but gotta replace the axle also. New freehub body is all aluminum, including the pawl carrier. The older ones had a pawl carrier screwed into the freehub body, causing many to split. 1998 thru 2006 hubs. Record/Chorus/Centaur

[RPS]

Can you post a picture of the seat tube damage?

Seat tubes are generally not highly stressed in the area of the FD clamp, so a “little” compression deformation due to over-tightening won’t necessarily make the frame unrideable as long as the general shape is intact. I’d be more concerned about whether any damage that may exist created a crease (since you used the word “crimped”) that could hide a crack. That, however, is highly unlikely.

In this case it’s good to keep in mind that some parts are intentionally bent as part of the fabrication process. Fork blades for instance are often curved by bending them significantly, and chainstays are often “deformed” to add tire clearance or (supposedly) to improve ride. Any damage that may exist would have to be severe before I’d worry too much about riding the bike. Having said that, a picture would reveal a lot.

[bahnbrenner]

Thanks for he help everyone. I'll post a picture later today or early tomorrow!

[old_fat_and_slow]

Its probably just be the paint. Gnarled up paint can look bad but not be a structural problem. Crushing the downtube with a derailleur clamp would be pretty hard to do -- think about it.

I agree with HenryA. Crimping the seat tube, just by over-torquing the braze-on adapter clamp seems highly unlikely, unless you've got yerself a super weight-weenie steel frame with ultra-thin tubes. A little local indentation seems plausible, but crimping the tube ? ?

If it really is crimped, I don't think there's an easy way to fix it short of replacing the seat tube. You can weld local doublers on too, to strengthen the crimped area, but it will look like sh*t.

Post photies when yah can.

[oliver1850]

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[bahnbrenner]

http://img59.imageshack.us/img59/9707/seatpostr.jpg (http://img59.imageshack.us/i/seatpostr.jpg/)

[benb]

Holy crap! I was going to say some manufacturers will actually put a dimple in an alloy seat tube for derailleur clearance. I had a Trek that had this.. big scare when I found it but it was supposed to be there.

But they don't look like that!

[Louis]

Wow. Is that FD clamp even the right size for that ST?

[old_fat_and_slow]

Wow ! That's unbelievable.

I don't see how you can fix that relatively painlessly.

I would probably just ride it, and inspect it before and after every ride. A crack may eventually develop, due to the stress concentration effect of that crimp. If that happens, stop riding the frame immediately, and either have the seat tube replaced, and repaint, or relegate the frame to wall art.

So sorry to see this happen to your frame. I never would have expected this from a steel frame.

[sc53]

Is this an April Fool's post?

[ultraman6970]

This was not made by accident the moron crimped the tube at purpose like that, it is too perfect. I would sue them or talk to the manager or something because it is impossible to crimp tubes with such perfection by accident, if you notice the crimp is longer than the clamp so clearly it was not an accident.

How to fix it now, this is what i would do:

- Sand the paint off
- buy some polyester putty paste in a body repair shop, the shop where a car body repair guy will get his stuff. NOT BONDO HERE OK? Needs to be polyester, if the shop has only bondo go somewhere else, that shop sucks. NEEDS TO BE ACRYLIC or POLYESTER!!! The reason of that is because once in place it wont crack or fell off as bonde does, besides it will stand changes in temperature. So use that potty and fill that nice and sand it smooth.

Paint over it, done!

http://www.autobodytoolmart.com/usc-icing-polyester-finishing-putty-p-10969.aspx



ps: I have worked with a 2 parts polyester/acrylic one and no problems so far, but never ever ever ever ever use BONDO to fix this.



http://img59.imageshack.us/img59/9707/seatpostr.jpg (http://img59.imageshack.us/i/seatpostr.jpg/)

[vqdriver]

Unless the dude crimped it down and then "adjusted" it higher cuz he mounted it too low. Crimped area extends below but not above. Either way that's a crap thing to do.

I'm surprised the threads didn't strip on that clamp.

[benb]

Or snap the bolt.. there is probably no real reason for the clamp to be designed to withstand that amount of torque.

[bahnbrenner]

If I see the guy again I am going to inflict some serious pain upon him. This bike is my first build, and is my pride and joy. I am really, really upset about it.

I adjusted the clamp upwards on the ST. I think I am going to call a Serotta dealer or something and ask them what can be done....

[vqdriver]

do you mean you moved it up the seattube off of the crimped area? meaning it is, in fact, the correct size?

that makes even less sense why this happened. i assume this wasn't a shop that did the work.

[stuckey]

Do not put body putty on it, it will not fix it, it will just cover up the damage and hide any cracks that develop. I have been a body man for 12 years and putty is not meant to actually fix stressed metal but to cover mild imperfections. If this is actually not a April Fools joke I would make the person who did that pay to replace the seat-tube.

[Marcusaurelius]

I seem to recall I was once quoted $250 to replace a seat tube. I am not sure if this is still accurate but I would contact either a local framebuilder or Serotta about the repair.

[Louis]

Just for the record, to correct my "you may be OK" statements made above before the picture was posted:

That might be OK to ride for a little while, but long-term that crimp is a almost certainly going to cause a crack to form and before long you'll have a nice little suspension system, then you'll have no frame at all (once it goes nearly every other joint on the bike will be overloaded in a manner that will cause another failure in very short order).

I'd say you have at least three options:

1) Ride it until the ST fails, then trash the frame.

2) Trash the frame now.

3) Spend the $ and replace the ST.

Good Luck
Louis

[salem]

First, I don't have a lot of metallurgy training, but I be inclined to guess that if the creases don't have any hard edges (they are smooth and rounded) you may be ok. That said, I would agree against covering the area with filler which would hide cracks. Better yet, locally paint the affected area white, as this will show any cracks best (dirt gets into the crack). You do want to keep an eye on it and don't ignore any creaking.

For some peace of mind, years ago, I was riding my father's old Wicked Fat Chance for a mountain bike ride when I didn't have my own bike. The pressed in bearings started to fail, and when I knelt down for a closer look, I found a hole the diameter of my finger in the back bottom of the seat tube where it had rusted out. 30 minutes earlier I had jump a roughly 4 foot drop off with no failure of the frame, and keep in mind, this was a fully rigid bike.

[HenryA]

Wow!
Worst I've ever seen - by far.

Hope you can get some relief from the "mechanic" who did that.

[oliver1850]

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[bahnbrenner]

Hi guys,

I saw the fellow who did this today, and he was extremely apologetic. He felt terrible, offered to pay and was visibly distraught....After a week of cooling down myself, I realize that he was just trying to help and that it was an honest mistake. Lessons learned for both of us.

On another note, I spoke with one of Serotta's flagship dealers (in Tacoma, WA) who were extremely helpful. At the end of the day this is going to cost at least $800 for a new seat tube and a repaint. As a college student who essentially sold his car to build this bike, it just isn't worth putting more money into. Besides, Club Specials just dont sell for that much. Even the nicest Club Specials, and this is by far the nicest one I have ever seen (online or in person) dont sell for over $1000, and I have already invested about $1400. So, I'm just going to ride it until it breaks....

[Louis]

So, I'm just going to ride it until it breaks....

Just out of curiosity, how much do you weigh?

If you're super-light you might be able to get quite a few miles / years out of it.

Some ideas that may help extend the life:

1) Spray inside the ST once / year with FrameSaver or Boeshield.

2) Remove the paint on the outside of the ST for an inch or so on each side of the problem, repaint with something decent.

3) Hope for the best.

Good Luck

[oliver1850]

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[Louis]

I don't know where you are

Above he says SeaTac

It's worth a shot, but would a reputable framebuilder be willing to do this?

[oliver1850]

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[WayneJ]

This is actually a fairly common situation, although this crimp is more severe than most. Here's an explanation:

As the bolt is tightened, the "ears" of the clamp are drawn together and deflect. That is, the gap becomes non-uniform with the gap smaller at the bolt and further apart at the clamp area. The sections where the ears meet the clamp rotate from this bending stress and turn in toward the seat tube. Now in place of having a gripping effect of the entire clamp distributed around the tube, you have two pressure points driving inward into the seat tube. It doesn't take that much torque to happen and some derailleur clamps are weaker and thus more prone to this than others. It really takes little torque to get an effective grip on the seat tube.

[WayneJ]

Also, I don't think any builder would repair that in any way except to replace the seat tube entirely. Building up that area with brass, outside the butted region would require putting a lot of heat into a damaged area. You would likely make it worse, structurally.

If you don't have seat tube bottle cage braze-ons, you could use a long mandrel to smooth the wrinkle from the inside by entering from the top of the seat tube. Personally, I'd put the clamp back in place, tighten it just right and ride the bike. Peek at the area occasionally to ensure no cracks develop.

[RPS]

So, I'm just going to ride it until it breaks....
If I decided to ride the frame with the dent (as it appears you’ve done already) I would find myself a short section of tube that is 1/8-inch larger in outside diameter and make a two-piece sleeve to fit around the seat tube (unless you can buy one already made), and then purchase a derailleur clamp that is 1/8 inch larger. That will reduce stresses around the tube and also hide the dent.

I have a Calfee frame (picture below) that came with such a sleeve around the seat tube with the main difference being that it is only split in one place. However, a dual split won’t be that different from a functional basis. I would just make sure neither split is over the damaged area. IMO it's not ideal but better than putting the clamp back on over the dent.

[oliver1850]

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[RPS]

What RPS suggests makes sense to me. A piece of carbon tube that has a 1/16" wall would be perfect. Fill the indention with good epoxy, cover with the carbon and clamp. Done with some care it would be decent looking and would be a lot stronger than leaving it as is.
Oliver, I personally would not use carbon or epoxy because the clamp will place stress directly over the dented area again. I’d keep it simple and just touch up the affected area before placing the shim over it.

I think a custom-made derailleur shim (so it can be a little longer) preferably of a stiff material like steel would be best, although aluminum would probably work also. If I was doing it for myself I’d use a short section of polished stainless tubing so I wouldn’t have to paint it to match.

Below is a picture of a standard derailleur shim. I’d cut one just like that but a little longer like on my Calfee so it would cover the entire dent.

[vqdriver]

see if something like this might work.
it came as a shim on a frame i bought recently. extra long shim. it measures 4cm long and comes in two halves.