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Ride this fork or toss it?

Old 02-09-20, 11:25 PM
  #1  
Dustintendo
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Ride this fork or toss it?

Previous owner dimpled this fork to clear wider tires. No cracks that I can see. Is this safe?




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Old 02-09-20, 11:58 PM
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I'm usually the "steel is real", that'll ride, you can fix that kinda guy, but I've never seen anyone dimple a fork before. If I had it in my own two hands I'd get you a better diagnostic, but with just pix, I'd say it's not worth it. I can't really give you a "why", but just about any part of a steel frame can break and you can safely come to a stop, but the fork is the holy of holies. I've replaced steerers and dropouts, but the blades go bad, it's just too risky.

I'd say not only toss it, but take a hack saw to one of the blades and cut it off so someone else doesn't find it in the trash
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Old 02-10-20, 12:04 AM
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Not only that but this was not dimpled, it was crushed, not sure if I'd even ride those.
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Old 02-10-20, 12:57 AM
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Now, I'm not going to say it's OK to ride that, so tell your next of kin not to sue me. But I've seen worse! Schwinn used to deeply indent the forkblades on some sorta high-end bikes, I wanna say "World" or was it "New World", in the 50s or 60s. Sorry I can't be more specific, I'm not a Schwinn expert, but I've seen a few, maybe even on a Town And Country tandem?

We're talking deep indents. Think of the deepest indent you've seen on a chainstay -- like that. I have one downstairs but I'm resisting going and getting it to take a picture, figuring someone here must have a picture of one of those already...

The reason I think it's likely OK is that it's below the heat-affected zone (HAZ) from brazing the crown. If the indent is below the HAZ, and the HAZ is the weakest point (can't be sure but it probably is), then the indents don't weaken the fork at all. If you stress it to failure and it fails in the HAZ, then any weakening from the indent is moot.

Still a dumb thing to do and ugly, but my best guess is it won't bend or break there.

Mark B in Seattle
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Old 02-10-20, 07:40 AM
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I have seen Trek urban cruisers with flats pressed into the blades, the designers engineers would built this into the design specifications and manufacturing process, not in any way an after thought. These however, appear to be rather scary uncontrolled smashing of the blades with lots of stress risers possible. In a somewhat controlled environment (not a 40 mph decline with a sharp corner at the bottom) they might be fine with a low likelihood of catastrophic failure but as gugie said the consequence of a fork failure can be very high (read new front teeth).
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Old 02-10-20, 07:49 AM
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Too ugly to ride.
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Old 02-10-20, 08:33 AM
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If that's rust (not just dirt/grime) where blades join fork crown - i would be as concerned about that as the indented blades. How does it look at the fork ends?
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Old 02-10-20, 08:52 AM
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Replace the fork would be my HO. Is that a Trek offering?
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Old 02-10-20, 09:53 AM
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There is a question here?
prior owner was a Gorilla, no mechanical sense.
Value of the fork vs. value of the rider's face.
I see no reason to do the math.
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Old 02-10-20, 10:18 AM
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considering that a replacement steel fork (chrome 27" wheelsize) is about $40 on Amazon I would say its not worth it to risk riding the "modified" (compromised) one. And gugie knows his stuff so heed his advice.
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Old 02-10-20, 11:17 AM
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Originally Posted by gugie View Post
I'd say not only toss it, but take a hack saw to one of the blades and cut it off so someone else doesn't find it in the trash
+1; I learned this technique from a buddy who works in an LBS. Barely 20 years old, could almost be my grandkid, but wise beyond his years. He actually showed me using a bolt cutter, to cut a dropout off from a damaged frame, but same principle.

Gotta wonder what the story is with this fork. Some ham-handed attempt to make a DIY fat-tire bike?
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Old 02-10-20, 11:54 AM
  #12  
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Yeah, I have a 3' bolt cutter that I'd try on this.
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Old 02-10-20, 12:00 PM
  #13  
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I think that I could do a quick test to see if this fork was good enough for rides to the store, but I wouldn't use this fork for hard riding and/or at higher speeds where a pothole impact could be more unexpected and more severe.

I'm wondering what sort of use that the OP might be hoping to get from this thing(?).

A big factor is also the loading on the bike, particularly the rider's size and of the possibility or it encountering a pothole at speed.

It would be interesting to install the fork and put the complete bike through some sort of standardized test of it's durability (under fail-safe conditions of course).
If the steel tubing still maintains a decent minimum cross-section then I think that it would be hard to impossible to make it yield while riding.

Attempting to first align this fork (certainly needed here) will instruct it's owner as to it's remaining strength, it shouldn't bend easily or "locally" even one blade at a time.

I am recalling a story from the BOB list about 17 years ago where a large rider from SF claimed that his Waterford road or touring bike's fork buckled at the blades while descending a trail with some kind of a rut crossing it. Obviously the combination of big rider and some degree of "impact" or overload occurred at the upper end of the fork blades which he thought indicated sub-standard strength. But in reality you could say that his adventure simulated an attempt to collapse the structure, where obviously some intense and sudden transfer of much weight occurred. On the other hand, I myself saw a 150# woman plow into a car door with only a mild degree of fork bending that was actually fixable, this on a mid-range Nishiki road bike.

Last edited by dddd; 02-10-20 at 12:05 PM.
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Old 02-10-20, 12:09 PM
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Originally Posted by bulgie View Post
Now, I'm not going to say it's OK to ride that, so tell your next of kin not to sue me. But I've seen worse! Schwinn used to deeply indent the forkblades on some sorta high-end bikes, I wanna say "World" or was it "New World", in the 50s or 60s. Sorry I can't be more specific, I'm not a Schwinn expert, but I've seen a few, maybe even on a Town And Country tandem?

We're talking deep indents. Think of the deepest indent you've seen on a chainstay -- like that. I have one downstairs but I'm resisting going and getting it to take a picture, figuring someone here must have a picture of one of those already...

The reason I think it's likely OK is that it's below the heat-affected zone (HAZ) from brazing the crown. If the indent is below the HAZ, and the HAZ is the weakest point (can't be sure but it probably is), then the indents don't weaken the fork at all. If you stress it to failure and it fails in the HAZ, then any weakening from the indent is moot.

Still a dumb thing to do and ugly, but my best guess is it won't bend or break there.

Mark B in Seattle
Mark, inside me I'm saying the same, but wanted to keep the message simple. If the dents were in a different plane, then it would be a no-brainer. The dents in that fork go through the neutral plane of the regular forces a fork sees. I'm just worried that I'm missing something in my thinking.

I haven't seen this before, you have, so I'm being very conservative here.
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Old 02-10-20, 12:17 PM
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@dddd has a good question about the intended use of the bike that may help determine what you wish to do.

I'd probably ride it, but keep an eye out for a replacement as soon as practical.

I suppose one might ask where one would expect the fork to fail. The most common place of lugged fork failure is between the crown and the blades, and not in the middle of the blades. You have some new and unique stress points introduced.

I suppose the other issue. There is some debate about the necessity of extended tangs on the fork crown for reinforcement, which yours doesn't have. But, that would provide additional support if you had it.
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Old 02-10-20, 12:25 PM
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I said toss it when I saw the title of the thread. I have lost faith in a couple of forks and stopped riding them because of that, with no particularly good evidence there was anything wrong with them.
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Old 02-10-20, 01:15 PM
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A bike with a fubar fork isn't going to ride right and handle well without some serious tinkering/hammering/bending/ alignment, is it? Even with a bunch of work, there's no guarantee that it will be right and surely it's not cost effective to have a professional do it. Riding a misaligned bike is just no fun. It's like a Raleigh Sports on a logarithmic scale. Don't think it would be worth even thinking about -- get a decent fork, install it, and ride. 86ing that sucker is probably a good idea, too.
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Old 02-10-20, 06:38 PM
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I'd have a go at fixing it. I'd be more concerned about misalignment than loss of strength. You could braze a bolt onto the hammered-in section and pull it back out if you had facilities to do that. I don't so I'd drill a hole in the opposite side and use a short hardwood drift to hammer it back to where it should be, while holding the hammered-in section firmly against a hard surface. Then fill the hole with jb weld. 20 minutes work to save a good pair of forks.
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Old 02-10-20, 06:39 PM
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You could donate it to science.....

Clamp one drop out in a vice and reef sideways on the the other leg to see where the lucky wishbone breaks.
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Old 02-10-20, 07:07 PM
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Originally Posted by thinktubes View Post
Too ugly to ride.
Don't knock it till ya try it!
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Old 02-10-20, 08:55 PM
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Originally Posted by repechage View Post
There is a question here?
prior owner was a Gorilla, no mechanical sense.
Value of the fork vs. value of the rider's face.
I see no reason to do the math.
Exactly. It's not like you can't see the person who did this had any CLUE as to what they were doing.
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Old 02-10-20, 09:52 PM
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Im a Mechanic/Fabricator so I usually try to save everything that can be saved.But that fork is Special, So I suggest you repurpose it and use it for a game Horseshoes.

Toss it.
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Old 02-10-20, 10:35 PM
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Originally Posted by aland2 View Post
I'd have a go at fixing it. I'd be more concerned about misalignment than loss of strength. You could braze a bolt onto the hammered-in section and pull it back out if you had facilities to do that. I don't so I'd drill a hole in the opposite side and use a short hardwood drift to hammer it back to where it should be, while holding the hammered-in section firmly against a hard surface. Then fill the hole with jb weld. 20 minutes work to save a good pair of forks.
Have you actually tried this??? Sounds like something you’d do to fix a metal fender...
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Old 02-10-20, 10:44 PM
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Originally Posted by gugie View Post
Have you actually tried this???
Hint - reference to a fork (singular) as a "pair of forks".....
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Old 02-11-20, 12:13 AM
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Originally Posted by madpogue View Post
Hint - reference to a fork (singular) as a "pair of forks".....
I think that beats a pair of threes..
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