Fixing bent fork?
#1
Thread Starter
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Joined: Sep 2007
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From: Far beyond the pale horizon.
Fixing bent fork?
The fork on my 25 year old Lotus got bent.
It looks like the fork is bent at the bottom of the head tube so that the blades are shifted (pointed) to the right side. It's not that far off (it's a bit hard to tell).
Any ideas of how I might get it back to a more normal state?
Here's a picture (1.5mb)
https://www.ramaposkiclub.org/images/IMG_1617.jpg
It looks like the fork is bent at the bottom of the head tube so that the blades are shifted (pointed) to the right side. It's not that far off (it's a bit hard to tell).
Any ideas of how I might get it back to a more normal state?
Here's a picture (1.5mb)
https://www.ramaposkiclub.org/images/IMG_1617.jpg
Last edited by njkayaker; 10-02-08 at 03:14 PM. Reason: Added picture
#3
#5
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Joined: Jun 2007
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From: mountains
Bikes: Alex Singer+ cheap mountain bike
I just love this photo of Ernest Csuka bending this frame with a bar.
Could be you may have to clamp that fork down and bend it true.
https://www.framebuilders.toucansurf.com/SingerCS.htm
Could be you may have to clamp that fork down and bend it true.
https://www.framebuilders.toucansurf.com/SingerCS.htm
#6
Randomhead
Joined: Aug 2008
Posts: 25,930
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From: Happy Valley, Pennsylvania
I just love this photo of Ernest Csuka bending this frame with a bar.
Could be you may have to clamp that fork down and bend it true.
https://www.framebuilders.toucansurf.com/SingerCS.htm
Could be you may have to clamp that fork down and bend it true.
https://www.framebuilders.toucansurf.com/SingerCS.htm
Bending a fork back from undergoing significant bending may result in localized thinning of material that will result in a very weak fork. There will probably be significant micro-cracking. Depending on if the steel was closer to gas pipe or high alloy steel, this may or may not result in problems.
#7
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Joined: Jun 2007
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From: mountains
Bikes: Alex Singer+ cheap mountain bike
unterhausen,
I am sure you are right about the forks.
It looks like Ernest has quite far to go if he is bending the frame in the photo to meet the pointer on the surface gage!
I am sure you are right about the forks.
It looks like Ernest has quite far to go if he is bending the frame in the photo to meet the pointer on the surface gage!
#8
Randomhead
Joined: Aug 2008
Posts: 25,930
Likes: 4,825
From: Happy Valley, Pennsylvania
parallax makes it tough, but it looks like he's actually past the pointer. Because of springback, you have to bend it past where you want to go. I just did this to get 130mm wheels in a vintage frame, it's a good time.
#9
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Joined: Sep 2007
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From: Far beyond the pale horizon.
#10
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From: yreka, ca
Bikes: like 15. my favorite a 1951 schwinn spitfire cruiser. also have a 1959 amf roadmaster, 1962 jch deluxe cruiser among others.
if i could, id replace it. a bend in the forks can ruin their integrity and safety of the bike. besides, back in the day when i tried to rebend bent forks, the bike never seemed to be the same again.
#11
You gonna eat that?
Joined: Sep 2008
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From: Fort Worth, Texas Church of Hopeful Uncertainty
Bikes: 1966 Raleigh DL-1 Tourist, 1973 Schwinn Varsity, 1983 Raleigh Marathon, 1994 Nishiki Sport XRS
I used an aluminum multi-ladder to straighten my fork. It was bent front-to-back, not side-to-side, but I just put the ends between two rungs and leaned real hard on the tube. In fact, to get enough leverage I attached it to the rest of the bike to do the unbending.
#12
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From: Boulder, Colorado
Bikes: Cinelli Supercoursa 69, Ritchey Breakaway Cross, Mondonico Diamond Extra 05, Coors Light Greg Lemond (built by Scapin) 88, Scapin MTB, Stumpjumper 83, Specialized Stumpjumper M4, Lemond Poprad 2001
Take it to an old school LBS or a frame builder. There is a tool that will help give the proper alignment in all directions and cold setting a fork is no problem. A good mechanic who can use this tool can usually "feel" when the fork is beyond help and the cold set has affected the metal negatively. I bent a cross fork back using the tool of a local frame builder/mechanic and it was much worse that your pic. Look on Park for an example of the tool.
Good luck
Good luck
#14
Senior Member
Joined: Mar 2008
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From: Montreal Quebec, Plateau
Bikes: 91 bridgestone rb-2, Univega viva sport, 04 masi Nouva Strada,Dave Scott Ironman, Changes like every month
I've messed up a few forks working on the street and I've found a few options. Have an LBS straighten it (cheap, effective). Get a new fork, a crowned 4130 model is $16 from Babac, a nicer molded crown version in better tubing is about $35. I've also seen/had done for me a ghetto a** process that involves taking the wheel off and pushing the blades against a curb. Though the last option was a short term fix for a wasted fork that was bent at the crown and therefore unsalvageable








