swampyankee2

Some astute observer pointed out that the forks on my Robin Hood Lenton Sports have taken a hit. I compared the forks to one that I have from a Robin Hood 3 speed and the stem looks to have a different angle than the headtube on the LS. Other clues start to make sense, including a replacement front rim and a slightly notchy feel to the steering which is still there after cleaning and greasing. So my guess is that it's tweeked along the strm somewhere.

Has anyone had success straightening a bent fork? I have full access to a tool and die shop where I work, so fixturing and presses are no problem.

Mr. 66

Notched feeling due to indented races is not abnormal for an aged headset, depending on the headset one can use loose bearings to replace caged or vise versa to smooth out. For me the real questions would be, Is the steertube bent? Does the headset feel loose at one point, and bind in another when rotated 360'? Another check is to roll the steertube on a flat surface.

Alignment needed on an old fork is not uncommon.

top506

I do not recommend it, but it can be done.

Top

swampyankee2

This. I didn't roll the stem since the grease was so dried up it seemed a safe assumption that it just needed a good clean and lube. I need to pull it apart and give it a good check, and straightening.

repechage

drop fork, straightedge on the steerer at least around four longitudinal tangents.
Straightening a steerer SOMETIMES can be done. I do not like doing it.
if that is OK or corrected, then with an alignment jig, work the blades.
I think this is a job for a grey haired mechanic with tools.

dedhed

https://www.google.com/search?q=stra...hrome&ie=UTF-8

swampyankee2

So, after reading about the various methods, both on and off the bike I decided to take a crack at it by rigging up a hydraulic jack and some brackets I made from 2x4 pieces to go between the BB and the forks. I figured I had nothing to lose but to try. As you can see, in the before, the bend was not nearly as bad as Top's. I used a fork from a Robin Hood 3 speed as a gage, and eyeballed it as well. The frame is identical to my Raleigh Sports so I checked the wheelbase before and after and found 39-1/2" before and 40-1/2" after, which matched the Sports. The fork turns smoothly through 180 degrees now. I will remove it and inspect for cracks and such.

52telecaster

It sure looks better.

Doug Fattic 

Ordinarily this fork alignment job is done by a framebuilder. There are 4 factors involved. 1st it is to get the rake back to original. That is the fore aft alignment. The rake needs to be the same on both sides. 2nd is the side to side alignment. The front dropouts need to be equidistant from the steerer's centerline. Framebuilders have fixtures for these checks. However I don't bend the blades in the fixture, I bend them outside the fixture and use the fixture to check. Gloves help. 3rd, the dropout faces need to be parallel to each other. There are dropout alignment tools for this job. They are sometimes referred to as "H" tools because that is how they were designated in old Campy catalogs. They were the tool between G and I.

Once the fork has those 3 alignments, it can now be checked that a wheel centers exactly. There are a couple of solutions to do that including filing one of the DO slots. Most frame builders charge a reasonable fee to do this and it can be done while you wait.

Classtime 

Nice mod. A 2 X 4 combined with the-one-eye-closed-squinting-jig has straightened a few forks and rear triangles around here.

52telecaster

The park tool fork alignment jig has greatly improved a couple of my rides.

swampyankee2

Probably worth doing for a high-end, high-value classic bike.
But for a $70 gas-pipe frame Raleigh-type (Robin Hood, actually), it worked out. I felt that the fork was "fixtured" in the frame as it was when the damage occurred, the forces would focus on straightening the point where it was originally bent. As said, I will pull the fork and check for cracks, and fine-tune alignment, etc. I work in the tool and die industry and as such, have precision fixturing and measurement tools at my disposal.

They don't call me a "swampyankee" for nothin'

52telecaster

You'll get it I'm sure. If it pulls you'll know you need a little tweeking but high tensile steel is pretty forgiving stuff, as I'm sure you know.

Kabuki12

I had taken a Motobecane GJ of my daughter's to a small bike shop to have new tires installed . The guy who runs the shop is a retired racer/ Ferrari mechanic with a very nice selection of bicycle tools and jigs. When he went to put the front wheel on , he noticed it didn't look quite right. He took out a gage and check the alignment of the fork tips to the fork and found they weren't right. He spent about half an hour with a jig and straightened it out for her. The whole job with tires , installation, and fork alignment was about $100 . I thought it was very reasonable and the bike was worth it. He said that he has seen new bikes that are not correctly aligned so not to worry about if the bike had been damaged in an accident.

WGB 

Little Brute

never done (or wanted done) more than a tiny adjustment

cudak888 

FYI, the forks on the OP's Lenton were bent back a smidge, but the repair appears to have bent the forks too far forward as the frame has significant front-end damage. Note the wrinkle under the top tube.

It seems as if the fork repair did, in effect, straighten the frame too, but it's not there yet. The headtube damage needs to be pulled out first before any more eyeballing will work.

-Kurt

branko_76 

I personally would not straighten a fork while attached to the frame, it seems there are added variables that could complicate the process and possibly damage the frame.