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Is my fork bent?

Old 12-02-19, 05:34 PM
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Zen10NiN
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Is my fork bent?

Might be posting this question in the wrong forum.
I am building up a 73 falcon San remo. Started with just a frameset. Well I got some campy high flange wheels and when I put the front wheel in it doesnít seem to be centered. When I push the wheel so the axle is snug on both sides of the dropouts the wheel seems to be a little bit closer to the left. Pictures might be necessary. I did have to straiten this frame. It was bent and I didnít know that when I bought it. I thought it was just the back half tho it wasnít off much and I bent it back by cold setting. Rear wheel is great. My question is it possible the fork is bent? It doesnít seem bent to the eye how do I measure? Could it be the way the axle is situated? Do I have a cone too far to one side? Need some help. Thank you.
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Old 12-02-19, 05:41 PM
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I think this is the right forum for that question, and if you don't mind I'd actually like to tack on a question which may answer both of us, if so that would be awesome, it's a great question.

I recently purchased a fork on eBay. Got one hell of a damn good price on it considering who made the fork and what it's made of, not to mention the quality of work.

However, I know the bike it came off had been in a very, very severe accident. Seller (who is quite possibly an opportunist picker) claims the fork was installed after the wreck. Hmmm.

Anyways, to @Zen10NiN 's point, is there any reliable way to remove the fork totally and check for it being in-shape, especially when you know the core frame isn't available OR is bent up?

I mean, we even have needle alignment gauges for turntables and such, is there any similar gauge or guide one can lay a bare fork onto to check if it's square?
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Old 12-02-19, 05:42 PM
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Do you have another front wheel to try? You could at least eliminate the wheel as the issue if so.
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Old 12-02-19, 05:46 PM
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Originally Posted by francophile View Post
I think this is the right forum for that question, and if you don't mind I'd actually like to tack on a question which may answer both of us, if so that would be awesome, it's a great question.

I recently purchased a fork on eBay. Got one hell of a damn good price on it considering who made the fork and what it's made of, not to mention the quality of work.

However, I know the bike it came off had been in a very, very severe accident. Seller (who is quite possibly an opportunist picker) claims the fork was installed after the wreck. Hmmm.

Anyways, to @Zen10NiN 's point, is there any reliable way to remove the fork totally and check for it being in-shape, especially when you know the core frame isn't available OR is bent up?

I mean, we even have needle alignment gauges for turntables and such, is there any similar gauge or guide one can lay a bare fork onto to check if it's square?
The fairly rare Park fork alignment tool is what you need. An old-school shop or a frame builder near you might have one.
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Old 12-02-19, 05:49 PM
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...there are a few things that can cause this, so you ought to post some good photos. Check to see if one of the fork ends has been narrowed a little bit, so the axle is not bottoming out on that side. Basically, remove any quick release or other stuff on the outside of the fork ends, insert the wheel, and look for any gaps on the side that is high. Sometimes back in the 70's, a bike would come through with this problem in fork alignment. There is a way of bending the fork leg on that side to compensate (matching the curves is not essential , but the final position of the fork ends in parallel are). But it's not something for the faint of heart. And it requires some tooling to check the fork alignment that no one has any more.

If the fork ends are genuinely off level in allowing a trued and properly centered wheel to sit in the fork with equal distance between the legs of the fork, it's usually simplest to use a round or half round file to lower the end that is high. Do this by putting a blank axle or wood dowel in them to judge, and then remove and replace it as you file little by little to check you're not taking off too much and going past where you need to go.
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Old 12-02-19, 05:54 PM
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Originally Posted by francophile View Post

Anyways, to @Zen10NiN 's point, is there any reliable way to remove the fork totally and check for it being in-shape, especially when you know the core frame isn't available OR is bent up?

I mean, we even have needle alignment gauges for turntables and such, is there any similar gauge or guide one can lay a bare fork onto to check if it's square?
VAR made one, and Park made a couple of different ones. NObody makes and sells them any more because of liability issues with shops bending frames/forks back into shape. they show up on ebay pretty regularly at exorbitant prices, and whenever a really old bike shop goes out of business. They're pretty easy to figure out how to use. I have one, a VAR, and I use it all the time. Most people are not going to use it enough to warrant the purchase costs.

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Old 12-02-19, 05:59 PM
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Originally Posted by 3alarmer View Post
...there are a few things that can cause this, so you ought to post some good photos.
One I saw someone posted recently was a person had opened up the fork-end to accept a larger axle, but drilled the fork-end off-center, so the axle wouldn't sit straight. I believe it was cudak888 maybe on his Legnano thread?

Originally Posted by nlerner View Post
The fairly rare Park fork alignment tool is what you need. An old-school shop or a frame builder near you might have one.
Good call. I literally just missed out on a frame alignment tool on AuctionZip because the seller called/passed on a huge chunk of their lot. (I forget the correct term)

Super bummed. I'll need to see if my LBS has one. Those guys have all kinds of crazy stuff.
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Old 12-02-19, 06:11 PM
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I recently had a Univega that had symptoms like the op's San Remo. The front wheel was dished perfectly, and the fork looked great to the naked eye. So ... I put a tiny, tiny dab of jb weld under one of the fork ends. It was still too much, so I had to sand it down and test the wheel multiple times to get it perfectly centered. But it was a quick, simple fix.

Pics of your bike would be appreciated by us Falcon folks.
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Old 12-02-19, 06:29 PM
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I suspect the fork has some damage since the rear triangle has been damaged as well. It will be an exercise in frame alignment to check to see that all is in good place.
The accident damage will in most cases create a frame that will jump back into the frame damaged state even after straightening it. (from personal experience).
You must check all frame dimensions and alignment in a frame gauge or with a similar tool. Even then there is no guarantee that it will stay in the re-aligned position. The frame will always be suspect, and may at any time jump back into the misalignment caused by the accident. So be warned to watch for the signs that it might not always track well. JMHO, MH
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Old 12-02-19, 06:43 PM
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First, check to see if your wheel isn't dished to one side (front wheels should be centered on the hub faces). Easiest way is to put it in your fork, then flip it around back in the fork. It should be skewed to the same side by the same amount.

Sometimes the Park tool that @nlerner mentioned is just the ticket. Sometimes it needs more. Here's the order I check out forks in:
1. Dropouts are parallel, centered, and properly spaced (typically 100mm) Dropout alignment gauge and the Park tool is used for this.

Dropout alignment gauge - 50 year old Zeus model from my LBS days. Used to check for parallelism. A set of calipers measures spacing


Park tool in action. Note that the gauge slides up and down the bar. It has two flats on the bottom to clock it when tightened. First thing is to put the steerer in the jig loosely, "zero" the blades with the gauge up near the fork crown, then lock down the steerer so the fork won't rotate. Slide the gauge up and down the blades, especially looking at the dropouts to see if they're centered. If that doesn't fix it,

2. Check to make sure the dropouts are in the same plane. If they're not, the gauge won't go into both dropouts easily.

3. ...then the distance between the fork crown and each dropout is uneven (not the same). Adding or subtracting a bit of rake to one of the blades has the effect of shortening or elongating one side. The tool to do this properly doesn't exist for purchase that I know of, so I made my own. I don't like the idea of putting force on the joints (fork crown to blade, blade to dropout), so the tool only touches the blade.

The Babe Ruth of fork rerakers


Babe in action



Bending a fork blade should be done by someone with experience.
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Old 12-02-19, 08:23 PM
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Zen10NiN not sure if it's interesting to you or not, but someone is selling brand new Park FFS-2 on eBay right now for $72/shipped, which is about $20-30 cheaper than "normal" and only $10 more than the cheapest ones have sold used in the last 6mos or so (unless I missed one cheaper).

https://www.ebay.com/itm/193103942112
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Old 12-03-19, 08:00 AM
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The only '70 Falcon San Remo I have seen was a stunner with spearpoint lugs. As gugie said assuming you don't have a dish issue and this is a keeper you might consider checking with a framebuilder. A few years ago our local framebuilder straightened a bent Reynolds 753R frame and fork (Reynolds states 753R is not supposed to be able to be cold set) for $100 on Marchetti frame and fork table. I tried the fork myself before taking it in as it looked straight forward but after twice getting it straight and having it pop back as soon as I mounted the bike I took it in. 1,000s on miles later you can still ride around the block no hands.
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Old 12-03-19, 12:16 PM
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In gunsmithing I've used a boresight laser gizmo for scope alignment on the bench. It works pretty well.

I wonder if a laser could be "boresight mounted" inside the steerer tube and then a target (with the shape of an inverted "T") clamped between the dropouts.

A perfectly straight fork would have the red dot land on the center of the "T" and show the intended distance from the crossbar corresponding to the fork rake.

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Old 12-03-19, 12:31 PM
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Originally Posted by easyupbug View Post
The only '70 Falcon San Remo I have seen was a stunner with spearpoint lugs.
..the history of Falcon, as you are probably aware, is a little confusing with regard to model names. I've seen "San Remo" used on several levels of Falcon bikes, but the top end ones in sky blue are, indeed, very nice looking bicycles.

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Old 12-03-19, 09:37 PM
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DIY fork alignment tool from BMX foot pegs. Might make one if I didn’t know where to find the proper tool....

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Old 12-04-19, 10:40 AM
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Two possibilities. An improperly dished front wheel or bent fork. If the situation chances when you flip the wheel, then the wheel is probably the culprit. If no change, definitely the fork's geometric integrity that is the issue. And, for what it is worth, a frame is easier to straighten than a fork set (my opinion).
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Old 12-05-19, 09:07 AM
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Thank you guys!

Thanks guys Iíve got it sorted! Wheel is sitting perfect now thank you for all the tips. Hereís some pics for you guys!

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Old 12-05-19, 09:21 AM
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@Zen10NiN so what was the problem?
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Old 12-05-19, 09:25 AM
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It still looks bent backwards slightly in the first photo.
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Old 12-05-19, 11:25 AM
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that's an easy fix
P1030007, on Flickr
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Old 12-05-19, 01:35 PM
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Originally Posted by Zen10NiN View Post
Thanks guys Iíve got it sorted! Wheel is sitting perfect now thank you for all the tips. Hereís some pics for you guys!

...that's one of the nice ones. Swell bikes.
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Old 12-05-19, 01:59 PM
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Originally Posted by seypat View Post
It still looks bent backwards slightly in the first photo.
That was my thought too. I realize this isn't always an accurate way, but at the angle of the photo, straight line confirms something could possibly be hinky.

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Old 12-05-19, 04:36 PM
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.
...apart from the fact that you need to take photographic distortion into account, if you want to do a straight line test, you need to do it along the back of the fork and head tube. The fork rake will guarantee that dropping a line along the front of the head tube to the wheel axle will never line up.
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Old 12-05-19, 06:36 PM
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Originally Posted by 3alarmer View Post
.
...apart from the fact that you need to take photographic distortion into account, if you want to do a straight line test, you need to do it along the back of the fork and head tube. The fork rake will guarantee that dropping a line along the front of the head tube to the wheel axle will never line up.
I did both, actually, but trying to see if the line was straight with the muddy line between the back of head tube with dresser behind it made it difficult. But even then, the line was definitely going thru the middle of the lower half of the fork blades.
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Old 12-06-19, 11:51 AM
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"One accurate measurement is worth a thousand expert opinions."

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Pull it out and measure the rake.



I'm guessing on this bike that it should be 40-50mm. If @francophile is accurate on his photoshopped line, you're way under that.
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