Is my fork bent?
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Is my fork bent?
I just picked up a well worn Falcon ten speed and as I'm looking more closely at it I'm starting to wonder if the fork is bent. The fork does not appear to be parallel with the head tube. Is this how it's supposed to look? Is this a wreck waiting to happen? If the fork is bent can it be bent back? I would love to get any of your opinions. Thank you!
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Looks bent to me.
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I find it difficult to judge by the photos. The DS looks worse than the NDS.
Minimal bends without creases can be repaired if one has the right tools.
Minimal bends without creases can be repaired if one has the right tools.
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The joke on Bike Forums is every fork is bent in a picture. The angle of many photos makes it hard to tell if the blades are really parallel with the head tube or not.
Having said that, it really does look like your fork blades are bent backwards.
Having said that, it really does look like your fork blades are bent backwards.
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Not necessarily bent. There were forks produced with that negative angle in order to reduce fork rake. You may want to remove it and inspect carefully, but don't assume that it's bent. Does the wheel sit straight? Usually if a fork gets bent, it ends up crooked, even if it is a head-on collision. Also, has the front wheel been replaced? It's hard to bend a steel fork without damaging the rim at the same time.
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Jeff Neese Nah, it's bent. There are loads of pictures of Falcon bikes from the same era on the intertubes, and they do not have a fork the is steeper than the head angle. Not saying such a bike doesn't exist, but a lower cost bike like this one is very unlikely to have a non-standard fork as stock.
Also, forks get bent all the time without damaging the wheel - the wheel can hold the weight of the rider + bike + momentum of riding through some uneven terrain in any direction(because it is round), while forks are designed to hold that weight, but only almost directly along its length, and a front-end collision delivers the blow in exactly the wrong direction.
You are correct that a bent fork will often also be misaligned and cause the bike to pull to one side or otherwise mess up the way the bike rides. Often, but not always. Many people happily ride bikes for years that have forks obviously been bent from a collision.
However, even if it is bent, it's probably still ok to ride if it doesn't pull to one side. SOP used to be to use a tool to push between the bottom bracket and fork to bend back a damaged fork such as this, and this re-bending would cause the fork to lose some strength, but it would still be considered OK to ride. So riding it after the initial bend, if it rides OK, shouldn't be an issue.
Also, forks get bent all the time without damaging the wheel - the wheel can hold the weight of the rider + bike + momentum of riding through some uneven terrain in any direction(because it is round), while forks are designed to hold that weight, but only almost directly along its length, and a front-end collision delivers the blow in exactly the wrong direction.
You are correct that a bent fork will often also be misaligned and cause the bike to pull to one side or otherwise mess up the way the bike rides. Often, but not always. Many people happily ride bikes for years that have forks obviously been bent from a collision.
However, even if it is bent, it's probably still ok to ride if it doesn't pull to one side. SOP used to be to use a tool to push between the bottom bracket and fork to bend back a damaged fork such as this, and this re-bending would cause the fork to lose some strength, but it would still be considered OK to ride. So riding it after the initial bend, if it rides OK, shouldn't be an issue.
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Head on collision bent... New fork needed until proven otherwise...
Note: I have been disappointed with purchasing used forks. It would appear there is always something a little wrong with them and the cost of a new fork is not that much more. About 40 USD should get you a usable fork that is new and reliable...
Ebay - ORIGINAL 27" Steel Bicycle Fork 1" Threaded Caliper 304 Chrome Bike Fork
Note: I have been disappointed with purchasing used forks. It would appear there is always something a little wrong with them and the cost of a new fork is not that much more. About 40 USD should get you a usable fork that is new and reliable...
Ebay - ORIGINAL 27" Steel Bicycle Fork 1" Threaded Caliper 304 Chrome Bike Fork
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The other thing to look at is the top and down tubes. When forks get pushed back from head on collisions as that appears to have seen, the frame tubes get stressed heavily,often bending just behind the head lugs. Look at those two tubes. Is there a small bulge just behind the lug on the underside of the tubes?
This fork can be straightened as can the frame tubes. This bike is common steel which takes quite kindly to being straightened. With a quality straightening this frame is probably good for many more miles. (Quality meaning the force to re-bend the frame is just enough to get to "right", not past and having to bend back. Better to live with some remaining funk.) If you do this, periodically look for cracks.
This fork can be straightened as can the frame tubes. This bike is common steel which takes quite kindly to being straightened. With a quality straightening this frame is probably good for many more miles. (Quality meaning the force to re-bend the frame is just enough to get to "right", not past and having to bend back. Better to live with some remaining funk.) If you do this, periodically look for cracks.
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You are correct that a bent fork will often also be misaligned and cause the bike to pull to one side or otherwise mess up the way the bike rides. Often, but not always. Many people happily ride bikes for years that have forks obviously been bent from a collision.
However, even if it is bent, it's probably still ok to ride if it doesn't pull to one side.
However, even if it is bent, it's probably still ok to ride if it doesn't pull to one side.
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The other thing to look at is the top and down tubes. When forks get pushed back from head on collisions as that appears to have seen, the frame tubes get stressed heavily,often bending just behind the head lugs. Look at those two tubes. Is there a small bulge just behind the lug on the underside of the tubes?
.
.
Looking at the bike it has a nicely lugged frame, probably original brake and gear levers, nice replacement callipers and.... a plastic dork disk
Maybe the dork disk is original, but my experience is that once one has spotted one cheap or repaired thing one should continue by asking oneself the question as to how well this bike has been maintained by its more recent owners?
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It does look displaced about 1/2-3/4". Does the fork rotate easily 360'? The forks legs are relatively easy to realign, shorten and lengthen more complex, but if the steer tube is bent that's a different beast.
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Put the steerer in a vise. Easy fix.
Or just limit your photography to behind/in front of the bike.
Or just limit your photography to behind/in front of the bike.
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Bent. If you know an old bike shop, they might still have a bending jig to correct it. Kind of like a bumper jack that went between the fork ends and the BB. Many Schwinn shops had them. You can improvise other methods too but it takes a lot of force. Steel is real.
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Thank you everyone for all the thoughtful replies! I especially enjoyed the bent kitchen fork image.
I've come to the conclusion that yes the fork is definitely bent. The front brake and front wheel both appear to have been replaced at one point which certainly hints at some sort of collision. And while bending it back would be a fun thing to try and might improve the ride quality, I don't feel great about further weakening the fork. In any case I've decided it's going on craigslist for parts only. Hopefully someone can find some use for it. Thanks again for all the suggestions :-)
I've come to the conclusion that yes the fork is definitely bent. The front brake and front wheel both appear to have been replaced at one point which certainly hints at some sort of collision. And while bending it back would be a fun thing to try and might improve the ride quality, I don't feel great about further weakening the fork. In any case I've decided it's going on craigslist for parts only. Hopefully someone can find some use for it. Thanks again for all the suggestions :-)
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#19
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Is there any way to repair a bent fork without a fork jig? Other than guessing, and trying to ride the bicycle without hands, or see what kind of trail the wet tyres leave to asphalt, or "feeling" how the bike handles?
Seems both rear and front fork were bent on my bike. I could not see any damage, creases or anything, but the rear and front dropouts were not parallel to each other. Rear bend was quite small:
I made the dropouts parallel with the tool, and cold set the frame to 130mm. String test showed some variance before cold setting, but I adjusted accordingly and now the string says the forkend is straight, and dropouts are parallel.
There's no such test for a fork. I assume you need a fork jig. No one here in Finland has one, I called around. I don't know anyone who has one. Anyways, the fork looks straight to the eye, but dropouts were bent. Probably the right side only. Or left. Who knows!
I made a blind guess: bend the right side dropout to make it parallel with left. Now fork dropouts are parallel and I mounted a rim. The edge of the rim is 2mm closer to the right blade. This persists even if I remove the rim, rotate it around and mount it again in different way. I tested another rim and the issue was the same.
Seems both rear and front fork were bent on my bike. I could not see any damage, creases or anything, but the rear and front dropouts were not parallel to each other. Rear bend was quite small:
I made the dropouts parallel with the tool, and cold set the frame to 130mm. String test showed some variance before cold setting, but I adjusted accordingly and now the string says the forkend is straight, and dropouts are parallel.
There's no such test for a fork. I assume you need a fork jig. No one here in Finland has one, I called around. I don't know anyone who has one. Anyways, the fork looks straight to the eye, but dropouts were bent. Probably the right side only. Or left. Who knows!
I made a blind guess: bend the right side dropout to make it parallel with left. Now fork dropouts are parallel and I mounted a rim. The edge of the rim is 2mm closer to the right blade. This persists even if I remove the rim, rotate it around and mount it again in different way. I tested another rim and the issue was the same.
Last edited by Ihmemies; 08-31-22 at 09:22 AM.
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Is there any way to repair a bent fork without a fork jig? Other than guessing, ...
There's no such test for a fork. I assume you need a fork jig. No one here in Finland has one, I called around. I don't know anyone who has one. Anyways, the fork looks straight to the eye, but dropouts were bent. Probably the right side only:
I made the fork dropouts parallel and mounted a rim. The edge of the rim is 2mm closer to the right blade. This persists even if I remove the rim, rotate it around and mount it again in different way. I tested another rim and the issue was the same.
There's no such test for a fork. I assume you need a fork jig. No one here in Finland has one, I called around. I don't know anyone who has one. Anyways, the fork looks straight to the eye, but dropouts were bent. Probably the right side only:
I made the fork dropouts parallel and mounted a rim. The edge of the rim is 2mm closer to the right blade. This persists even if I remove the rim, rotate it around and mount it again in different way. I tested another rim and the issue was the same.
If you are sure your wheel is true and dished equally, the problem you describe is often caused by fork ends that are a little out off square. You can carefully file the interior of the high side, to repair this so the wheel sits straight. But it cn be caused as well by something in the wheel, like being dished unequally, or someone taking it apart and replacing the axle with one spacer missing, of using different width cones or lock nuts on each side.
It's not that uncommon to find this on a bicycle that was sold this way, during the boom years in the 70's.
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#21
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I have a thick glass plate to cover one of my tables. I could use it. The crown is shaped so that the blades are at the highest points so it can sit straight on the plate.
I tried two wheels from different bikes and I tried rotating them around, and the problem was the same with both wheels and with both sides.
With a straight edge the forkends seem to be flat. So I will remove the fork and look at it on the table.
I serviced the headset with new bearings, 50+ loose 4mm steel balls. I will hate removing the fork but I should have checked if it is straight first, which I didn't.
No one seems to be selling affordable fork jigs either so the only options are crude methods, new fork, or make my own jig..
I tried two wheels from different bikes and I tried rotating them around, and the problem was the same with both wheels and with both sides.
With a straight edge the forkends seem to be flat. So I will remove the fork and look at it on the table.
I serviced the headset with new bearings, 50+ loose 4mm steel balls. I will hate removing the fork but I should have checked if it is straight first, which I didn't.
No one seems to be selling affordable fork jigs either so the only options are crude methods, new fork, or make my own jig..
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...just guessing, the most likely cause seems to be that the fork ends are sitting in such a way that they hold the wheel with one end of the axle slightly higher. As stated, this was not at all uncommon to find on cycles, even when sold new here. I've run into it several times, on used bikes I bought ( I have a VAR fork jig, bought long ago ). The professional fix is to slightly re-bend one of the fork legs, so that both ends are now level. The curves to the legs do not have to match, in order to hold the wheel straight relative to the fork crown and frame. But a much easier repair is to file one of the fork ends lower, while holding the fork by the steerer in a stand, clamp, or soft jaws in a vise. Use a round file of the proper diameter, and go slowly, reinserting the wheel from time to time, and measuring distance of the rim to each fork leg. If it's only off by 2mm, it won't take very long to accomplish.
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#23
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Hmm, filing of the forkend might be the most sensible way. Being off by 2mm at a position 30cm away from the forkend, it should take a lot less than 2mm of filing. I need to get a correct size "rat's tail" file or whatever they are called. Thanks for the suggestion!
If I file the side where it's leaning towards, it should fix the lean and move the rim to the centre.
If I file the side where it's leaning towards, it should fix the lean and move the rim to the centre.
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Hmm, filing of the forkend might be the most sensible way. Being off by 2mm at a position 30cm away from the forkend, it should take a lot less than 2mm of filing. I need to get a correct size "rat's tail" file or whatever they are called. Thanks for the suggestion!
If I file the side where it's leaning towards, it should fix the lean and move the rim to the centre.
If I file the side where it's leaning towards, it should fix the lean and move the rim to the centre.
You don't need to try multiple wheels, though it's a bit easier with a wheel that is true. Flip the wheel around (at the same point of course, I like the valve stem location) and see how it sits. If the wheel is true it'll sit the same both ways. If not, adjust until the wheel is equally off both directions. Rubber mallet works as well, just don't over do it.
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Is there any way to repair a bent fork without a fork jig? Other than guessing, and trying to ride the bicycle without hands, or see what kind of trail the wet tyres leave to asphalt, or "feeling" how the bike handles?
Seems both rear and front fork were bent on my bike. I could not see any damage, creases or anything, but the rear and front dropouts were not parallel to each other. Rear bend was quite small:
I made the dropouts parallel with the tool, and cold set the frame to 130mm. String test showed some variance before cold setting, but I adjusted accordingly and now the string says the forkend is straight, and dropouts are parallel.
There's no such test for a fork. I assume you need a fork jig. No one here in Finland has one, I called around. I don't know anyone who has one. Anyways, the fork looks straight to the eye, but dropouts were bent. Probably the right side only. Or left. Who knows!
I made a blind guess: bend the right side dropout to make it parallel with left. Now fork dropouts are parallel and I mounted a rim. The edge of the rim is 2mm closer to the right blade. This persists even if I remove the rim, rotate it around and mount it again in different way. I tested another rim and the issue was the same.
Seems both rear and front fork were bent on my bike. I could not see any damage, creases or anything, but the rear and front dropouts were not parallel to each other. Rear bend was quite small:
I made the dropouts parallel with the tool, and cold set the frame to 130mm. String test showed some variance before cold setting, but I adjusted accordingly and now the string says the forkend is straight, and dropouts are parallel.
There's no such test for a fork. I assume you need a fork jig. No one here in Finland has one, I called around. I don't know anyone who has one. Anyways, the fork looks straight to the eye, but dropouts were bent. Probably the right side only. Or left. Who knows!
I made a blind guess: bend the right side dropout to make it parallel with left. Now fork dropouts are parallel and I mounted a rim. The edge of the rim is 2mm closer to the right blade. This persists even if I remove the rim, rotate it around and mount it again in different way. I tested another rim and the issue was the same.
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