Framebuilders - Increasing fork rake
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Has anyone ever increased fork rake on a finished forK? It would work out cheaper, though not much, to use a Surly fork on my touring bike. I was planing on making the fork from scratch. The one problem with the Surly fork is that it is 5 MM too low in rake, I need 50 degrees for my head angle. Forgetting about the paint, is it easy to bump up the rake?
I don't doubt I can tweak the blades in my JD2 bender, but I was wondering how easy it is to do with conventional bending gear and whether this kind of alteration is ever done on completed forks?.
I don't have to worry about the impact on the frame of adjusting the forks since the frame won't be started until the forks are done, and all the geometry issues can be custom built to the fork.
05-10-06, 06:10 PM
The problem with adding rake to an existing fork is that you will shorten it. So if you do attempt it, do a little at a time and check to see if your wheel will clear the crown. Also shortening the fork is going to lower the front of the bike making the head angle steeper and the top tube slope downward. More rake and steeper head angle will mean less trail which is often not a good thing.
05-12-06, 04:57 PM
05-12-06, 05:04 PM
When did Mr. Moulton show up?
Hey, y'all. Want to have some fun? Go to Mr. Moulton's blog and read up:
DM here is one of the greats. Bicycle frame royalty.
Nice of you to join us, sir.
I'm off to read what he's posted.
I'm not concerned about the design issues because the fork is long enough, the 5MM I need to offset it won't change the length or brake position enough. I won't build the frame until I have the fork in final form. So, all I really need is info on the best way to bend a fork. I did get some good back channel ideas, but the more the merrier.
05-23-06, 12:43 AM
Adding more rake is easier than reducing rake since it bends the metal in the same direction. I've stuck the dropouts underneath a door and placed a semi-circle cutout of a wooden cylinder underneath the bend (similar curvatures). Then just pulled down on the steerer-tube using a 4-ft section of plumbing pipe inserted over it. Didnt' take much force, maybe 40-60 lbs or so.
07-09-06, 10:52 PM
I'm a frame rider and frame student not a builder, but I had a good builder decrease the rake of my chomoly Trek 610 fork to increase trail. He seemed very familiar with the technique, and felt he could reverse the change if I wasn't happy with the results. Don't know what kind of bender he had, but he said he had a bender.
So, my guy thought he could bend it in either direction.
In this on again off again thing I decided to make the fork from scratch, and that is underway. Still an interesting topic, to me...
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