650b conversion gone awry

[Leif Eckstrom]

I was trying to indent the chainstays on this vintage 531 frame, and I obviously went too far. 

Could someone please advise me on what to do next? Have I committed a mortal sin against this frame?

I'm hoping that some quick brazing and filing could repair the damage that I've done with torched paint around the repair. That might be wishful thinking, however. Have I effectively killed this old frame?

The crack is on the inside of the non-driveside chainstay near the chainstay bridge and is about 23 mm long. 

Many thanks to any and all with experience repairing broken frames and cracked tubes. 

Best,

Leif 

Chicago

[Ian A]

Leif,

I don't have an answer, but would recommend posting this on the iBob list. There's at least two frame builders who regularly read the list and who might give some information on whether the chainstay can be repaired or if it needs replacement. 

I feel your pain.

IanA

[Mark Bulgier]

That's a pretty quick 'n' easy repair -- just flow some brass in the crack, and add enough to make a little fillet down in the bottom of the valley.  Just a little, barely past the point where the crack is filled.  No need to file it afterward, just braze it quickly and it'll be smooth enough.

Probably worth taking the time to drill stop holes at the furthest extent, of the crack.  Small holes, 3/32" maybe, 1/8" max.  Optional.

I would expect that repair to last forever, or until the frame breaks somewhere else.

Mark Bulgier
Seattle

[peter weigle]

I agree with what Mark said except I wouldn't drill the extra holes ,, no right or wrong here just a gut feel.

To me the most important part here would be to have a good builder in your area do the brazing. This isn't rocket science but having a pro with good torch skills do it will help your cause, and right now you need all the help you can get.

If the builder doing the repair thinks the optional holes should be there allow him to make that call.  

PTR

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[Eric Keller]

On Wed, Jun 7, 2017 at 1:17 AM, Mark Bulgier <ma...@bulgier.net> wrote:

Probably worth taking the time to drill stop holes at the furthest extent, of the crack.  Small holes, 3/32" maybe, 1/8" max.  Optional.

I think in this case that drilling is probably counterproductive.  For one thing, these aren't fatigue cracks. The smaller the width of the crack, the better.

Eric Keller

Boalsburg, Pennsylvania

[Harold Bielstein]

You might consider using Filet Pro rather than brass. http://cycledesignusa.com/wp/?page_id=55
Flows at lower temps.

> On Jun 7, 2017, at 6:28 AM, Eric Keller <kell...@gmail.com> wrote:
>
>
> On Wed, Jun 7, 2017 at 1:17 AM, Mark Bulgier <ma...@bulgier.net> wrote:

> Probably worth taking the time to drill stop holes at the furthest extent, of the crack. Small holes, 3/32" maybe, 1/8" max. Optional.
>

> I think in this case that drilling is probably counterproductive. For one thing, these aren't fatigue cracks. The smaller the width of the crack, the better.
> Eric Keller
> Boalsburg, Pennsylvania
>

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Harold Bielstein
5211 Meadowlark Dr.
Rapid City, SD 57702
605-341-0315
hkbie...@gmail.com

[peter weigle]

I feel brass would be the better choice here in the hands of a skilled brazer.

It would be stronger and less fussy about contaminates from inside the stay which would be near impossible to clean out now that the frame is together.  

While you're at it I would look at the other stay and maybe consider filling some of that one also in case it's almost the point of wanting to split open like the side you showed us. At least both sides would look the same when finished.

The alignment and spacing will need to be spread/ checked when the frame is cool.

PTR

On Wed, Jun 7, 2017 at 8:53 AM, Harold Bielstein <hkbie...@gmail.com> wrote:

You might consider using Filet Pro rather than brass. http://cycledesignusa.com/wp/?page_id=55
Flows at lower temps.
> On Jun 7, 2017, at 6:28 AM, Eric Keller <kell...@gmail.com> wrote:
>
>
> On Wed, Jun 7, 2017 at 1:17 AM, Mark Bulgier <ma...@bulgier.net> wrote:
> Probably worth taking the time to drill stop holes at the furthest extent, of the crack.  Small holes, 3/32" maybe, 1/8" max.  Optional.
>
> I think in this case that drilling is probably counterproductive.  For one thing, these aren't fatigue cracks. The smaller the width of the crack, the better.
> Eric Keller
> Boalsburg, Pennsylvania
>

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Harold Bielstein
5211 Meadowlark Dr.
Rapid City, SD 57702
605-341-0315
hkbie...@gmail.com

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[Nick Favicchio]

I'm VERY thankful for the builders chiming in on this. I've crimped two frames now and seen lots of people crimp and suggest crimping and this is the first I've heard of or seen it go arwy.

Knowing that flowing a bit of brass in there fixes it up good in case things go poorly - great to know.

Thanks builders!

[Eric Keller]

On Wed, Jun 7, 2017 at 10:36 AM, Nick Favicchio <nickfa...@gmail.com> wrote:

Knowing that flowing a bit of brass in there fixes it up good in case things go poorly - great to know.

I told him off-line that he could try brass, but that on my bike, I would replace the chainstays.  Flowing brass in there is hackery.  It probably will work, at least for some time. It would definitely be worthwhile monitoring for further cracking around the stay.  I urge due caution while dimpling stays, because it very well could ruin the stay.  That's a very expensive repair if the hack job doesn't hold.  Uneconomic for most frames like that.

Eric Keller

Boalsburg, Pennsylvania

[peter weigle]

Nick,

Eric's got it right,,, this is less than an ideal situation and even with the brazing, it will never be as good as new(of course).

But Leif doesn't have a lot of options here and imo this is certainly worth a try. It will probably work out ok as long as the person doing the brazing is good.

PTR

--

[Leif Eckstrom]

Thanks, everyone, for chiming in with your experience and thoughts. I'm relieved to hear that flowing in brass to set up a nice fillet might work well enough to ride again for a while. Thanks for the suggestions on materials and especially the reasons why. Glad to have a teaching moment come out of my naivete! Thanks, Peter, for the added suggestion of doing both stays while the flame is lit and then re-aligning frame and spacing following the procedure. 

Nick, for the record, I went a step too far and tried to push the crimp on the non-driveside closer to the chainstay bridge in order to make more room for fitting an inflated Hetre in this frame with horizontal dropouts. I thought it would be ok because I was close and the crimp on that side would then match the crimp on the drive side, but either that was too close to the chainstay bridge (and the angles and forces too steep) or I simply cranked down too far with the vise. Whatever the case, I've learned to be a bit more cautious with crimping in the future and that I should have a better idea of how much of a turn on the vise is acceptable and how much squish is possible with these chainstays. Not objective measures, necessarily, but still, I could have tried a bit harder to know how much movement I was expecting of these stays and whether that was a reasonable objective or not. 

In short, crimping still seems a good idea recommended by many, but there also seems to be a reason why it's still relatively difficult, uncommon, and fussy to make vintage bikes with decent (but not excessive) clearances accept a 42 mm tire (and fenders, especially so).  
Thanks again for all of the correspondence on this problem. I really appreciate the generosity of experience here. 

Oh, and if anyone knows of a good framebuilder in Chicago, I'd love to hear a recommendation. Otherwise, the fix might have to wait until I've moved to the Pac-NW. 

Best,
Leif

[jack loudon]

Lief,

I have an honest comment (not a troll).  It seems like the non-drive chainstay is just about the least likely frame tube or lug to fail during normal use (abuse and construction defects excepted).  This chainstay works mainly in tension, but also takes minor torsional forces (through the bottom bracket), that are mostly absorbed by the downtube and seat tube.  If this were my frame, to be ridden only by me and not sold in this condition, I would be tempted just to seal the crack against moisture and ride it.  After all, this isn't a fatigue crack caused by hard or prolonged riding, so it isn't automatically going to get worse or fail completely.  

Bicycle riding is fairly dangerous, but I would be far more concerned about a texting driver behind me, or a blowout on my newly-installed tubeless tires, than I would about a non-driveside chainstay failure on this bike.

Just my opinion,

Jack

[Mark Bulgier]

jack loudon wrote:

> If this were my frame, to be ridden only by me and not sold in this condition, I would be tempted just to seal the crack against moisture and ride it. 

I agree that you can just ride it without repairing it, and see what happens.  It might last effectively forever, in fact that is what I expect will probably happen.

In addition to the relatively light loading on a left chainstay, there's also the fact that the crack is down in a valley, closer to the central axis, so it is even less strained than the rest of the chainstay.

If the crack does grow, then you're looking at a chainstay replacement, often more expensive than the frame is worth, meaning the frame is dead.  So the brass braze repair Peter and I suggested might be a "stitch in time saves nine" kinda scenario.

My gut feeling is it won't break if you ride with no repair, just some sealer as Jack suggested -- silicone caulk?  But doing the brass braze repair I suggested is safer, if only by a tiny amount. 

So as Dirty Harry said, you've gotta ask yourself one question: "Do I feel lucky?"

Personally, I would ride it without the brass braze, 'cuz I'm curious.  I sometimes ride frames with cracks in them, to see what will happen.  This is a really dumb thing to do. "Professional driver on a closed course".  Kids, don't try this at home.

-Mark

[Leif Eckstrom]

Thanks, Mark and Jack, for these additional comments. I've contacted the framebuilder Doug Fattic and hope to have him look at it and lay down some brass in a couple of weeks. For those who don't recognize his name, he works out of Niles, Michigan (near enough to Chicago), and is now mainly teaching framebuilding classes, as well as doing charity work teaching bike building in the Ukraine. Older and wiser riders will likely recognize his name, as he's long been in the business, and is a very accomplished framebuilder. I learned about his framebuilding classes through the Two Serious Bikes blog, which is well worth reading, if you're interested. 

I agree, though, that it would be a relatively low risk proposition to ride the frame as is and see what happens. That will be my plan B. 

Best,

Leif

[Mark Guglielmana]

Leif, 

Where are you moving to? 

Mark

[Mark Bulgier]

Leif Eckstrom wrote:

> I've contacted the framebuilder Doug Fattic

Good move. You won't find anyone better than Fattic, for knowledge, experience, technical smarts, fabricating ability, friendliness, generosity, personal integrity (OK I'm just piling on words here you get the point).

If you haven't already, be sure to make his job as easy and pleasant as possibly by stripping all parts off the frame and cleaning off any dirt, oil or grease.  Ask him if he needs the paint off locally.  I would -- there's not much in this world I hate more than breathing burning paint smoke.  Anyone who does frame repairs has ways of dealing with the dirt, grease and paint, but still, any part of the job you can do yourself is probably worth doing. 

Mark Bulgier
Seattle

[Mark Guglielmana]

+1 

Brazing is the easier, zen like part. Prep and finish is hard work, makes my hands sore and dries them out from all of the scrubbing I have to do to clean my hands afterwords.

[Leif Eckstrom]

Great idea. How much paint removal would be necessary? two inches or so around the crack? for the entire circumference/area of chainstay in that vicinity of the crack?

Thanks!

[christian poppell]

Hi Leif,

I'm considering crimping my frame soon but am wondering how much extra clearance is to be expected? My current stays are flattened (ovalized?) but not dimpled in any way. I can fit 38s and a dimpled fender in there currently but am possibly looking to get a 42 in the future. In your experience (or any of the others) how much do you gain by crimping?

Thank you,

Christian

[David Parsons]

On Tuesday, June 13, 2017 at 4:41:55 AM UTC-7, Leif Eckstrom wrote:

Great idea. How much paint removal would be necessary? two inches or so around the crack? for the entire circumference/area of chainstay in that vicinity of the crack?

Thanks!

You'll end up burning the paint all the way around the chainstay, and at least an inch and a half either end of the crack.  So whether you do it or have some framebuilder do it for you it will be a lot nicer if all of that pesky paint is scraped off beforehand. 

[Mark Guglielmana]

For your situation, after defluxing and sanding all of the "bad" paint off, if you mask off the "good" paint, you can get a pretty good match in an area that is fairly hidden away. Use a few coats of acid-etch primer, a high build primer, then go to an automotive paint place that can match the color in an aerosol can product, you might have it match well enough so that you're the only one to know. I've done a couple of frame and fork repairs that were done this way, both customers were very pleased on the paint match. I have the primers and typically do that so the customer doesn't have to purchase those products, then I have them get the finish color locally. I don't need a nearly full can of paint that probably doesn't match anything I'll ever need, and the customer has touch up paint for future potential need. You might ask your frame repair person if they'll prime for you.

If you go that route, you can color match to the closest paint chip (less expensive), or leave the frame with the paint people and they'll iterate until it's a perfect match (a lot more expensive). Your call, but I've found the "paint chip match" works pretty dang well, especially down by the BB where it won't show. Your local paint person can give you their recommended procedure. 

[Leif Eckstrom]

Hi Christian,

The two Marks will likely have a better idea than me. 

One thing I noticed, however, was that it's not easy to get accurate measurements before, during, and/or after dimpling. I have a digital calipers, but it's tough to measure in the exact place each time and make sure the caliper is straight across the gap. Also, despite putting a 130mm hub in the rear dropout, my 126mm dropout clearance was reduced to 120mm during the crimping on my most recent attempt. In short, the chainstay is flexing with the crimping in multiple locations despite trying to isolate where it changes shape. I'd say a rough estimate is that 5mm of clearance is usually doable, but in my case both frames I tried this on had chainstay dents already. Given you don't have indents yet, maybe 5-10mm of change is possible. 

But your question brings up another thought I had about what the ideal dimpling shape should be. 

Getting a crease in the middle or making the indent sharply convexed in the center seems to be a protocol borrowed from the dimpling of Columbus tubing. I know Mark Bulgier wrote on one of the lists (I-Bob, I think) that he thought that design (versus flat crimping) was superior for handling stresses. I have no reason to dispute that, but since we don't need deeper valleys for these projects so much as greater space between chainstays, I was wondering if you could create a dimpling form that has both the shallow arc for pushing on the middle of the indentation (familiar from Columbus-style indentations), but also add another set of curves that would push on the shoulders (the top and bottom) of that indentation at the same time and wrap over the chainstay slightly so as not to crush the curve of the chainstay tube. Another thought I had after cracking that chainstay is that you could also control how much indent you wanted to attempt by limiting the height of the shallow arc to say 10mm tall. 

I hope this photo of a cut up C-Clamp illustrates what I'm trying to describe in terms of creating an indenting form that has compound curves to push on both the center of the chainstay and the top and bottom shoulders of that indentation--the locations where a fat tire would actually rub. The roughly cut edge of this clamp would be filed to a shallow and rounded arc (perhaps only 5-10mm tall) while the unmolested ridge of this clamp would press on the top and bottom shoulders of the indendation on the chainstay. What do you all think?  

For more background, here are some other photos of the indenting forms I've been making and the tools used. 

Here's the shape of a form that makes the columbus-style indentation. I harvested this bit of metal from a 8-inch C-Clamp that I bent trying to further indent a trek frame with columbus SP tubing. This form doesn't push on the shoulders at all; only in the middle; and it's about 20mm tall. 

Same form. Other angle. 

 

 Cheap c-clamps from hardware store provide an easy source of an indenting form. The plasti-coated one in the foreground was harvested from a 2" clamp that I bought from Ace hardware. I cut it up with a dremel cutting disc.

Here's my modified bench vice. 27.0 seatpost cheater bar. Taped 2-Foot Square was used on outside of chainstay to deflect force from bench vise doing the crimping. The 2-foot length ran from Bottom bracket to dropout along the chainstay. Other folks have suggested using a piece of angle iron instead. or a wood block as shown in the photos. With a tiny vise, however, the wood blocks were too fat to fit. 

Grateful for the discussion so far. I'm hoping to refine my tools and technique. Thanks, Mark and David, for the recent comments about the paint stripping issue and post-brazing cleanup/repair. 

Best,

Leif

[Leif Eckstrom]

And then there's this approach, https://m.youtube.com/watch?feature=youtu.be&v=oNX90sKhg0Q

Fellow-lister Will shared that link with me in an email.
Many different ways to crimp a stay!

[Mark Guglielmana]

I'm sure that's just how Peter Weigle does it...

😉

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[Andy Beichler]

I am confused.  Do I have to listen to that music while I do it?  I just want to make sure I do it right.

[Joseph Kopera]

Hi All,

I'll piggyback on this thread with a similar issue. Inspired by this thread, while stripping components off of my beloved 83 Trek 613 today to crimp my chainstays, I noticed this beauty oh the outside of the drive side chainstay, between the bridge and the BB. I don't know what caused it, nor how long my 250 lb self has been riding on it, but is it something I should be concerned about? If so, should anything be done about it? The metal is not broken, it just a deep dent. On

Joe
Western Mass.

Tuesday, June 6, 2017 at 8:47:37 PM UTC-4, Leif Eckstrom wrote:
> I was trying to indent the chainstays on this vintage 531 frame, and I obviously went too far. 
> Could someone please advise me on what to do next? Have I committed a mortal sin against this frame?
>

[Mark Bulgier]

Joe,

It's probably fine to ignore that dent -- ride and enjoy.  Maybe look for cracks now and then, but my guess is cracking there is very unlikely.

If you were repainting it, I'd be inclined to try pulling it out.  One way:

• Drill a hole at the bottom of the dent, then feed a nail through the hole from the inside -- I think you can maneuver it into position with your index finger through the BB shell.  The nail will have to be pretty short, like 1/2"
  
• Weld the end of the nail to a slide-hammer*, and start whacking, gently at first.  Don't try to get the dent back to 100%; you'll probably have to settle for mostly pulled out.
• If you're good with a hammer you may want to tap down the high spots that will probably remain around the rim of the crater.  Or leave them and fair them in with painter's putty (bondo) to reduce the visual impact.  Don't file them down, that's thinning the steel locally and can cause the frame to break there later.
  
• Not sure if I'd remove the nail, maybe braze it in place to close the hole.  Or remove the nail and close the hole however you like, all brass or put  a small bit of steel in the hole before brazing, doesn't matter much.  Fill the remaining depression with brass, overfilling slightly, then when cool and de-fluxed, file and sand it flush -- or near flush -- again, don't file down the high spots in the tubing.  It's OK to leave something for the painter to hide.  Might be possible to do it with silver instead of brass, but cleanliness is tougher to achieve since you can't clean inside.  Silver flux can't take care of contaminants as well as brass flux can.
  

* If you don't have a slide-hammer, you can buy one ($25 from Harbor Freight) but a simple one can be made easily and cheaply by just about any DIY-er.  It's just a rod with a stop at one end, and a weight that slides on the rod and impact against the stop at the end.

That repair is probably best reserved for high-end frames and/or valuable antiques.  Not worth it if the repair costs as much as you could get a nice undented used frame for, unless there's sentimental value.

Mark Bulgier
Seattle

[Nick Favicchio]

That's the video I watched before crimping my Soma GR to fit 2" knobbies. Used channel locks and a cassette removal tool wrapped in electrical tape.

Worked perfect.

Mark, I recall you made a very spiffy stay crimping tool...