Fork me!

August 30, 2009 5:46 PM

I need a new fork for my road bike. How do I shop for one?

As a result of a could-have-been-a-whole-lot-worse accident a few days ago, my carbon front fork is broken (Fortunately, nothing on my body suffered the same fate - just a concussion, some bruises and stiffness). I have never shopped for a fork before, the one that broke was the original fork from my bike; what sort of things should I be looking for in a fork?

My bike's aluminum with carbon seatstays, and I do like the carbon fork I had (it was Klein-branded, don't know if they made it or not but that's all I can find on it is the Klein name), but I have no idea whether carbon is better than aluminum, or stuff like that.

Also, pricing - assuming I do decide to go with a carbon fork, how much can I expect to spend for a decent one? I'm seeing things for $2-300, is that typical of a good fork?

posted by pdb to sports, hobbies, & recreation (9 comments total)

Yes, those are typical prices for a used high end carbon fork. The important details are threaded vs. nonthreaded headset compatibility, length, brake mounting compatibility, rake, and steering post diameter.

The steering post has to be the right type for your headset (threaded vs. nonthreaded).

The steering post diameter needs to be an exact match for your headset (though if you find a matching headset that matches your frame, changing out headsets may be worth it for the right fork).

If a used fork has been cut (this is shorthand for saying the steerer has been cut), make sure it is at least long enough for your headset and stem. Most used forks will have been cut by the original owner. You may want to consider taking out spacers and replacing them with a stem with a sharper rise if you find a fork that would otherwise be a desirable match.

There is a race for the bottom bearing of a threadless headset that is actually installed onto the fork. Save the one from your old fork if you want to keep your old headset, otherwise you will need to replace this part.

You will want to double check that the fork is set up for the kind of brakes you want: a) sidepull/doublepivot, b) cantilever/v, c)disk. Chances are you are looking for a fork made for sidepull brakes.

You will want to make sure the fork length is right for the wheel size you ride (most commonly 700c for road bikes).

You will want to make sure you can handle the rake of the fork. A smaller rake gives squirrelly steering and can cause your tire to rub or hit against your toes or even your downtube in extreme cases, a longer rake causes sluggish and difficult steering (which can lead directly to accidents, especially if it is new to you).

Right now I am riding with a used fork that the previous owner gave away after a crash (he had gotten mixed advice about whether the frame and fork were death traps or still usable, so he gave them both to me, I found them on a craigslist ad). I did a thorough check of the integrity of the carbon fiber and decided to risk riding on this fork. I will never be certain I made the right decision unless I give it an Xray, but if it ever fails that will be a good sign I made the wrong decision. Many used forks will be up for sale for similar reasons, and some previous owners may not be as forthcoming. Don't trust any used fork that has an irregular finish, has cracks or dents in it (no matter how small), or that makes any kind of creaking, cracking, or squeeking sounds (carbon fiber tends to shatter with disasterous results and little warning if it fails, but sometimes it will give these sorts of warnings. Carbon fiber making any sort of sound is always bad).
posted by idiopath at 6:23 PM on August 30 [2 favorites]

That's a typical price for a good fork. You can find one a bit cheaper if you're not that concerned with weight. To match the handling characteristics of your previous fork you'll want a fork with identical or nearly identical length and rake.

Hopefully the geometry specs of your bike are online.

I prefer a carbon fork to an aluminum one. You could also give your local shop a call in the morning.
posted by spikeleemajortomdickandharryconnickjrmints at 6:30 PM on August 30

idiopath has already given a good answer, but a few other points I wanted to mention-

1) You almost certainly want a carbon fiber fork and DO NOT WANT an aluminum fork. Aluminum forks tend to give a miserably, rough ride, and your hands/elbows will hate you.

2) Many carbon fiber forks have metal steerer tubes. In my opinion, this is perfectly fine and saves you some money.

3) Keep in mind idiopath's caveats, but I've had good luck with the 1 used fork I've purchased. It was a Look HSC3 which matched the rake of the aluminum fork I replaced on my old bike. The steerer was cut, but conveniently, it was cut to exactly the right length for my bike. I got it for a very good price on ebay and had no troubles with it. I think the owner had cut it shorter than he wanted it, but it was about 6-7 years ago, so I'm not positive.
posted by JMOZ at 7:25 PM on August 30

Also, if you give us the model/year of your bike, we can probably help you find the rake of your original fork. (It's often on either bikepedia or (surprisingly) epinions.com. This should also make it easy to find the steerer diameter (1 1/8" on most newish road bikes, but 1" on some older bikes).
posted by JMOZ at 7:28 PM on August 30

idiopath - that's all great information, I really appreciate it. I was already leery of getting a used fork, and I think I'll stay away from one after reading that.

spikelee - I'm not at all concerned with weight. I'm 6' 2" and 260 lbs so I'm not one to shave grams in the name of performance - I'd never notice the difference.

JMOZ - I had a Klein Carbon Pro until March, and that frame cracked (it was 6 years old and had 40K miles on it), and Klein doesn't make frames for the US any more. As a replacement, Klein gave me a Q-Pro (which ironically is the bike I wanted to buy but couldn't afford 6 years ago!). I can't be 100% sure of the year, but Klein stopped making frames for the US market in 2006 so I wouldn't be surprised if it was that old of a frame, even though it was new to me.
posted by pdb at 9:24 PM on August 30

I would like to clarify one of idiopath's points (I'm a bicycle mechanic): a smaller rake (offset) does not automatically give 'squirrelly' steering, nor does a longer rake give you sluggish steering. Rake is a factor (along with headtube angle) in the bike's trail measurement, which is a more accurate way to judge steering feel and handling. Replace the broken fork with one of identical dimensions (rake and axle-to-crown distance, or length) and your handling won't change. Muck with the fork's dimensions and you've effectively changed the geometry of your bicycle.

You may be interested in a carbon steer tube, which many riders report has better vibration damping than a metal steerer. By now most major manufacturers have no rider weight limit except on their superlight/racing models, but check to ensure.

Personally I preferred the full carbon Reynolds Ouzo Pro to the others I've ridden. YMMV.
posted by a halcyon day at 9:46 PM on August 30

I would go to a bike shop, especially if you're set on carbon, since carbon can asplode if it's cracked or damaged, and you can crack a carbon fork pretty easily if it has a carbon steerer tube and you install it incorrectly, or if it has the wrong geometry. Additionally, a shop can take a look and make sure that your frame doesn't have any additional damage that isn't visible to the naked eye. You could have stress fractures from the crash that cause your head tube to fail or other terrible things to happen.
posted by craven_morhead at 8:14 AM on August 31

craven - I am definitely planning on taking my bike to the shop, I don't really remember the crash itself (I had a grade II concussion as a result of it) and even apart from the broken fork, I don't trust it at this point until someone who is much better at bikes than me gives it a good critical once-over.
posted by pdb at 9:28 AM on August 31

This description (of an 03 Q-pro) suggests 1 1/8" threadless steerer is needed, and the original rake is 1.6". Looking at bikepedia for the '06, the steerer size is the same, so I'd say that's a safe bet. (It's pretty close to universal these days). The rake MAY have changed, but probably didn't change much.

Hope this helps!
posted by JMOZ at 3:30 PM on September 3