Stick a fork in it, it’s done. My fork, that is. So now what?

[JustinW]

Hi all,

My old-ish steed (ca. 2006) has a carbon front fork, a Fuji FC-400. Recently I noticed some cracking at the top on the right side where the fork meets the frame, and a check by the folks at Phoenix Bikes suggests that yes, this fork’s day is done.

So now what? I’ve never replaced a fork. I presume this is easy overall, but I can’t find an exact replacement, so how does one shop for a fork? I understand some of the specs, but in general do I want something that closely resembles the incumbent, or does that matter? Do I run a risk of changing the bike’s dynamics if I get “the wrong” replacement?

Thanks for any (good!) advice.

Topic

[Crickey7]

I have zero experience in this, so I am totally unqualified to offer advice here. But I think that the headset angle is built into the frame, so assuming you get one that fits and is of the same length, it should ride the same.

[bentbike33]

@JustinW 129667 wrote:

Do I run a risk of changing the bike’s dynamics if I get “the wrong” replacement?

The key measurement you need to preserve to keep the handling of your bike the same is called “rake”. It is the distance between parallel lines running through the center of the head-tube and the center of the axle. See http://calfeedesign.com/tech-papers/geometry-of-bike-handling/ for a good explanation of the relevant concepts.

[huskerdont]

@JustinW 129667 wrote:

Hi all,

My old-ish steed (ca. 2006) has a carbon front fork, a Fuji FC-400. Recently I noticed some cracking at the top on the right side where the fork meets the frame, and a check by the folks at Phoenix Bikes suggests that yes, this fork’s day is done.

So now what? I’ve never replaced a fork. I presume this is easy overall, but I can’t find an exact replacement, so how does one shop for a fork? I understand some of the specs, but in general do I want something that closely resembles the incumbent, or does that matter? Do I run a risk of changing the bike’s dynamics if I get “the wrong” replacement?

Thanks for any (good!) advice.

The new fork will probably come longer than needed and will likely need the steerer tube to be cut. Some people do it themselves, and some have a shop do it. The important thing is not to cut it too short because then it’s done and you get to buy yet another one. You can get it cut a bit long and add a few spacers in if needed. Youtube has videos I used when I built my mountain bike.

[peterw_diy]

@bentbike33 129674 wrote:

The key measurement you need to preserve to keep the handling of your bike the same is called “rake”. It is the distance between parallel lines running through the center of the head-tube and the center of the axle. See http://calfeedesign.com/tech-papers/geometry-of-bike-handling/ for a good explanation of the relevant concepts.

Also fork length (distance from axle to the seat for the lower headset race). E.G., you don’t want to replace a long fork that has room for big 35c tires and fenders with a short track fork that barely has room for a 23c tire. Rake is important but it’s not everything.

[trailrunner]

There are a couple of things you’ll need to specify on your new fork. Wheel size and brake mounts are obvious. You also need to match the steer tube to match your head tube and headset. You most likely have a straight 1-1/8 setup, but you should double-check that. As another poster said, try to match the rake and fork length between your old fork and your new fork as close as possible. On one of my older bikes, I couldn’t get a fork with the exact dimensions that I needed and stressed about it for a while, but when I got it installed, it was close enough so that it wasn’t a big deal.

Will you be reusing the headset? If so, you’ll want to take the crown race off your old fork and put it on your new fork. You’ll also need a new star fangled nut.

[hozn]

You might be able to just find another fc-400. Or maybe this is compatible? http://www.bikewagon.com/fuji-fc-440-700c-carbon-road-fork-1-1-8-in-white

Yeah, axle-to-crown and rake are key geometry measurements. Steerer tube diameter is critical to match your bike.

If new fork’s steerer tube is alloy, you can cut it with a pipe cutter. If carbon, you will want a carbon-specific hacksaw blade.

[Author]

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