I'm getting a new fork but kind of wanted to try re-raking my original fork.
It's a steel fork with around 43mm of rake.
I want to re-rake it and bring it back 10-15mm.
I've looked online and it seems that the popular method is just sticking the steerer/crown in a vise and using a long metal pipe over each fork blade.
Here is my question. My fork blades go straight down and have medium sized curve 2/3rd the way down.
To get a lower rake, would it be better to...
-Bend the whole blade back right from the crown?
-Brace the area right above the lower fork bend and try to flatten out the existing curve?
I did a quick photoshop explaining it.
Top picture is showing trying to get the reverse rake/bend right after the crown. This looks difficult since it's a lot thicker in that area.
Lower is showing right at the bend area. Of course I would need to brace right before the bend.
Which is a better idea to get negative 10-15mm?
The first question is why? Changing the rake for the same head angle will alter the bike's handling and not necessarily in a good way.
If you look at the forks, the lower part of the blade is round but the top part is oval. The rake was formed by bending the fork blade against a curved form at the point where the oval becomes round. That's where you need to bend it and the straight part needs to be supported.
Trying to bend it near the crown risks breaking it as the long axis of the oval cross-section of the tube is designed to resist bending. In any case, you'll have backward pointing forks which not only look odd but are probably weaker.
You will also need to make sure you bend both blades by exactly the same amount.
You could just ride really fast into a wall?
I've seen it done. Wasn't too hard.
No idea why you'd actually want to do it though.
I'm getting a proper track fork but I won't have it until sometime next month. I want to keep riding this bike though.
I just measured again...the fork is closer to 45mm and I have a relaxed head tube angle....the steering is very twitchy compared to my old Bianchi Pista with a 28mm rake and higher trail.
I want to decrease the rake to bring the trail up a bit so the bike is more stable at speed. I actually get nervous riding near people because I'm so used to relaxed steering...this thing is so ridiculously twitchy.
Were the results okay? Again, I'm doing 10-15mm which isn't that much. People make it sound like I'm trying to add a large curve to a straight blade fork.
In the short term yes (long term I dunno, he didn't come back again). Bloke brought a lovely but cheap old Italian crusier in (so thick walled steel). I'm not sure how but the forks were bent in (crash I think but there was no other signs of damage and I never asked). My boss (at the time) removed them. Placed them in the vice (with some wood to protect the metal) and pulled on them. Took a few goes to get the right angle but didn't seem more difficult than cold setting a frame. There should be some give in steel frames if done carefully.
As I say it was a cheap cruiser thing (looked good though) so precision wasn't super important. I think the owner had been riding on the bent forks for a while before noticing.
Get a hammer and hit it until satisfied.
Gas pipe steel yes, 501 yes, 531 probably ok, any heat treated steel or aluminium absolutely no.
10-15mm probably won't do it much harm. It was probably cold set by hand originally. I'd flatten the original bend or it'll look terrible. The problem you'll probably run into is getting both sides the same. You'd be better off clamping the skinny ends between two blocks of wood and pulling the thicker ends of the fork and I'd do the bend in multiple points along the existing curve so as not to over-strain one point.
You can do this with leaf springs to lower a car. Put it on its side on the floor and draw round it with chalk. Then draw a new line with your desired curve/rake. Tweak a little at a time and offer it up to the new line. Repeat until happy. She'll be reet.
I'd just leave it and learn how to handle the bike that way it was originally built.
after having a pair of forks snap at the crown, I'd never mess around with them
There's some info here probably worth reading (and PDF link at the end) http://alexwetmore.org/archives/473.html
I know Ryan/Oak Cycles helped re-rake a fork for one polo player but he's off somewhere on the other side of the world now... Seem to remember it involved large planks of wood and they only managed to decrease the rake by a few mm... Those were fairly heavy duty unicrown forks, originally intended for rigid jump riding though...
Thanks Jonny69, that was super helpful.
Yeah, the frame is SL tubing but the fork was most likely low end gas pipe. Not even sure if the fork was original or taken off a road bike. I measured again and it was definitely in the 43-45mm rake range.
The bike has track bike geo....75/75 head and seat tube.
Unless you've ridden a bike with a 75 degree head tube and nearly 45mm of rake, I really wouldn't comment. The head tube/fork rake combo gives puts the TRAIL at 45mm which means SUPER twitchy. To give you an example, my last Pista was around 65mm trail. Remember, neutral handling is around 60mm so a 45mm trail is very twitchy.
So I took two wood blocks and sandwiched the lower fork blades between right at the end making sure it was perfectly even on both sides. Not going to tell how I put enough pressure on the blocks but I used a bar on the steerer tube and just pulled down a little. Flattened right out and my final measurement came out to around 32mm which is a lot better. One drop out needed just a tiny tweak but after that they measured perfectly. Axle fit smoothly, etc..
Took the bike out today and it handles SO much better. Just tracks smoothly with none of the previous twitchy handling. I'm getting a proper low rake fork next month (nice Columbus helical tubing this time) so I'm looking forward to this. The bike is 100% easier to ride now.
Yeah, it has a minor kink in the bend but not bad.
I am looking to do the opposite. I want to buy a Tange Prestige Track fork at 38mm rake and bend it to a 45mm? I cannot find a Road version, unless I keep my eye on ebay. Is waiting on ebay a safer bet?
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