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-   -   Steel Fork Bent, Can It Be Repaired? (https://www.bikeforums.net/showthread.php?t=1201144)

branko_76 05-12-20 09:54 AM

Steel Fork Bent, Can It Be Repaired?
 
I realize that it would be better to replace the fork, but I would like to keep the bike original.

Is it possible to repair it?

There are no other visible signs of damage to the frame or fork, head-tube looks to be free of damage. It's nothing special, just high tension steel from a 1970's era Raleigh Super Grand Prix.

https://cimg0.ibsrv.net/gimg/bikefor...ca0e3b0a40.jpg

Doug Fattic 05-12-20 10:01 AM

Yes it makes sense to try and bend the blades back. The original straight fork blades were bent a lot to get the curve. Where do you live in Michigan? I'm in the SW corner just above South Bend Indiana if you want to bring it by. I've got all the tools and knowledge.

branko_76 05-12-20 10:04 AM

Looks to be about a 2 hour drive to South Bend, I'm wondering if I can bend it back myself?

Although I'd love to see your shop.

Doug Fattic 05-12-20 11:23 AM

The problem is to know when to bend until everything is in the right place. There are a lot of checks. For starters you need to bend both blades back until they have the same rake as they originally had. I have a fixture to accurately measure the rake. Then you have to check that both blades have the exact same rake and furthermore bend the blades so the dropouts are equidistant to the steerer's centerline. And finally you have to make sure that the dropout faces are exactly parallel to each other. For this we use Campy H tools. Park makes some dropout alignment tools but they are not accurate enough to my liking. And then we have to check with a true wheel to see that it centers. The rebending process may have made one blade longer than the other. A bit of filing can center the wheel again. And since one aspect can move after another one is bent, it is necessary to repeat the whole process until the fork passes all tests without more tweaking.

My frame shop is in Niles and you are welcome to come over as long as you don't bring the Coronavirus with you. I'll walk you through it. I'd be willing to bet that you could have driven back and forth several times in the time it would to figure out how to do it yourself with any accuracy.

branko_76 05-12-20 11:28 AM

Thank you. There's no urgency so when things cool down, hopefully soon, I'd love to stop by.

Andrew R Stewart 05-12-20 07:16 PM

branko 76- I would strongly consider taking Doug up on his gracious offer. Besides repairing the fork and learning a lot along the way Doug is a really good person and I'm sure you'll enjoy his company. Andy

Sluggo 05-23-20 10:18 AM

Messrs Fattic and Stewart are more knowledable than me, but it looks to me like the steerer is bent just above the fork crown. That is something that "nothing special" forks are vulnerable to. Not so easy to fix, but can be done with an appropriate mandrel.

Andrew R Stewart 05-23-20 09:41 PM

Hard to tell is the steerer is bent right at it's base or if the crown is where the twist is, besides the likely blade bends. I've "fixed" steerer bends (to a degree, pun intended) by re facing the crown race seat. Andy

steve sumner 05-31-20 11:21 AM

branko, if you visit Doug ask him if b4 he got a fork alignment table
and jig did he ever use my spokes trick?

Andrew R Stewart 05-31-20 07:40 PM


Originally Posted by steve sumner (Post 21507483)
branko, if you visit Doug ask him if b4 he got a fork alignment table
and jig did he ever use my spokes trick?

Steve- Do tell us your spokes trick? Andy

steve sumner 06-01-20 08:30 AM

clamp steerer in vise using blocks with blades horizontal. lay 4 or 5 spare sokes
across blades in intervals to use as a visual guide as to where to make corrections.
I learned it from Keith Lippy when he was the instructor at a regional occupational program
for bike repairs in 1972 in San Diego. worked in shops for 26 yrs. and straightened
at least 100 forks that way. tried to walk Branko thru the process on another forum
that's why I brought it up.

Andrew R Stewart 06-01-20 05:47 PM

Steve- Good idea. Much like what I've done but with a few straight lengths of whatever was laying about. Never considered using spokes. Andy

unterhausen 06-02-20 07:26 AM

interesting variant on winding sticks https://www.google.com/search?q=wind...iw=877&bih=487

Andrew R Stewart 06-02-20 07:49 AM

https://www.bikeforums.net/bicycle-m...ard-right.html Here's a link to my reply to a fork alignment thread many years ago. Some might find it interesting, others might not:) Andy

aland2 06-17-20 08:49 PM

When I was 17 a pakistani man drove a Datsun Sunny in front of my Lambretta Li 150 by doing a right turn.
It had a fork with a normal axle. Fork was bent back and the scooter's handling was severely compromised.
After my leg healed I removed the fork and stuck it in the drain grid outside the house and heaved on it until it looked right.
Job done.


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