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Fork alignment... Good Grief!

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Fork alignment... Good Grief!

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Old 05-11-21 | 06:08 PM
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Fork alignment... Good Grief!

I've been working on my Gitane Grand Sport Dlx. Bit by bit trying to make it as good as it can be. The bike pulled heavy to the left when I got it and I was living with it, but decided to tackle the fork. A few bending attempts left and right got me no where. I dropped the fork and did some examining. Basically it was going every which way. Fork ends were off, blades were off and it looked to me like at one time the blades must have been squashed. Maybe run into or over by a car perhaps. Lots of trial and error, bending this way and that I finally got the wheel centered and the bike steers neutral. What I have though is a very asymmetrical fork. Question is, does it matter?

I think a lot of these bikes had issues with the fork right out of the box when new. Most bikes of this vintage that I get have a steering problem. And these forks are pretty spindly and soft compared to a higher level Reynolds531 bike with forged ends.
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Old 05-11-21 | 07:45 PM
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I have nothing to add other than to say that bike's color scheme is truly inspirational!
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Old 05-11-21 | 07:50 PM
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Can you take the fork to a frame builder and have him assess it?
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Old 05-11-21 | 09:53 PM
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I don't think it matters if the blades aren't exactly the same shape. Just the position of the fork ends relative to the steerer should be close to correct. At least that's what I told myself the one and only time I "adjusted" a fork myself. I don't know if your pic is before or after, but it looks great!
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Old 05-11-21 | 10:02 PM
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Originally Posted by Insidious C.
I don't think it matters if the blades aren't exactly the same shape. Just the position of the fork ends relative to the steerer should be close to correct. At least that's what I told myself the one and only time I "adjusted" a fork myself. I don't know if your pic is before or after, but it looks great!

....this. I've done a lot of forks over the years, and have had access to both a Park and a VAR fork alignment jig.
In the final analysis, the important thing is to get the ends where the wheel clamps into the fork to be in a place where they are symmetric with respect to their offset from the centerline of the bike, properly spaced for the hub you are using, parallel to each other, and more or less in the correct fore and aft position that ou are close to the original fork design's rake and trail specifics.

I have several bikes where the fork legs are not identical, but they still ride fine after some creative adjustments.
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Old 05-12-21 | 05:20 AM
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Did you check the frame alignment?

I agree with [MENTION=364898]Insidious C.[/MENTION]
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Old 05-12-21 | 05:21 AM
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Thanks for the replies. I kinda figured it wouldnt make a difference. I did have a framebuilder that was just a mile from my house but now is retired.

Rooney, Gitane orange was a really unique color. Kinda has a yellow ochre undertone to it.
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Old 05-12-21 | 06:09 AM
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Originally Posted by big chainring
Thanks for the replies. I kinda figured it wouldnt make a difference. I did have a framebuilder that was just a mile from my house but now is retired.

Rooney, Gitane orange was a really unique color. Kinda has a yellow ochre undertone to it.
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Old framebuilders often keep tools and tooling.
worth an ask.
I agree that on Gitanes the tip to steerer alignment is the goal.
these frames Often arrived with the rear triangles out of alignment- a quick string test should get you to the basic answer.
now if a properly dished wheel is not center at the brake bridge... a more organic problem.
one dropout off vertically would not be a surprise.
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Old 05-12-21 | 06:54 AM
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It looks in the photo like the blades may still be pushed back a bit, though this can sometimes be attributed to cameras with a short focal length lens. If it steers fine, I wouldn't worry further about the alignment.

My only concern is the "squashed" blades, by which I assume you mean they have been deformed so that they have a thinner cross section laterally? If so, then the lateral stiffness of the forks has been compromised. If there are creases due to the "squashing", that further reduces the stiffness. I definitely would not ride any fork with creases in the blades. Hard cornering and especially riding out of the saddle could be a concern, as they place large lateral loads on the fork. Basically, the probability of a failure boils down to the amount of blade deformation and the aggressiveness of your riding style.
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Old 05-12-21 | 07:07 AM
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Originally Posted by 3alarmer
I have several bikes where the fork legs are not identical, but they still ride fine after some creative adjustments.
This. It's extremely common for blades not to be perfectly brazed into the crown, or tweaked so that identical adjustment just isn't possible - though one can selectively bend the blade with a Park FFS-1 to get them closer to each other.

It's also absolutely imperative to cold-set the dropouts with a pair of adjusters as well; bent dropouts on a straight fork will shift the wheel's position regardless. Granted, sometimes even after all the possible straightening, the wheel might ride cockeyed in the fork. At this point, I file the dropout on the side the wheel tilts to - but ONLY IF I am 100% certain that I have the blades perfectly aligned with each other.

Also, as crazy as this sounds, if a fork is obviously twisted but not directly bent to the side, sometimes one can get away with putting a dummy wheel in the fork and then using the stem and bars (provided the wedge is strong enough to prevent slipping) against a wheel held between the legs to bend the fork straight again. I don't always recommend it, but on a fork which is twisted only, this can both re-bend the blades and the dropouts perfectly back into their original location. Again, this has very limited applications, and only works if the force that caused the bend was the exact reverse of your twisting motion to straighten it.

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Old 05-12-21 | 07:38 AM
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Yeah, it does appear that the head tube is lined up with the back edge of the fork blades, rather than an imaginary line down the middle of the blades. But as T-Mar said, camera angle and distance / focal length creates perspective distortion. It would help to stand directly to the right of the head tube / fork, rather than at the "middle" of the bike. If your camera has an optical zoom, standing back and zooming in would help as well.

Last edited by madpogue; 05-12-21 at 07:48 AM.
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