Bicycle Mechanics - New Fork

Hi,

I am new here. I have a Cannondale R300 and want to start upgrading some of the components. At this point, I am looking at replacing the fork with a carbon fork. What are the sizes/specs that I need to make sure I get? Are all forks fairly standard, or will they vary depending on the size of my frame? Is this something that a do-it-yourselfer could do? I assume that I will also need a new headset/stem to accomodate the fork? Thanks for any help you can provide.

The most critical dimension is the steerer/headset diameter of your current fork. The choices are 1" or 1-1/8" and your new fork will have to match what is already there. Assuming you want to go threadless and your current fork is threaded, you will need a new headset and a new stem to go along with the fork. Threadless forks all come with an over-long steerer and you have to cut it to match the handlebar position and height you want. You many need a few to several spacers under the stem to get the bars at tthe desired height and you will have to install a star-nut (steel or Al steerer) or a compressor plug (carbon steerer).

This is a straight-forward upgrade IF you know what you are doing and are comportable with bike mechanics. Look at the Park Tools web site to get a feel for the procedure.

There are two main characteristics of forks that have to match. First, there's the steering tube diameter; that's the thing that sticks up through the frame and that the stem clamps onto. There's a couple standard sizes, although 1 1/8" seems to be the most common. Secondly, there's threaded and threadless forks; threadless is the newer standard.

Getting the old fork out isn't that hard; the only thing holding it in there is the pressure from the stem and top cap from the above. Pull the stem and the top cap off, pull off the spacers, and the fork should slide right out.

Putting the new one in... You'll need to install a new crown race on the new fork, you'll need to cut the steerer tube length to the proper size, and you'll need to install a new star-nut / compression plug. None of it is very hard, but the official tools to do this aren't the cheapest. Search the forums and you'll find ways of making home-brewed alternatives.

And then there are the fork rake and fork length to consider.....

Follow-up question:

If the spec sheet on the bike says that the headset is 1" does that mean the steering tube diameter is also 1"? I don't see how a 1 1/8" steering tube could fit through a 1" headset, but we could be talking about apples and oranages. I really don't want to have to take my bike apart in order to buy the new fork if I can avoid it. Thanks for your help.

Yes, a 1" headset implies a 1" steerer tube.

1" headset means you need a 1" steerer as well.

Does your bike use a quill stem? or threadless?

If it is a quill stem , then you must buy a replacement fork with the right length threaded steerer or you have even more work than if it is threadless (cutting and threading versus just cutting)

Some information on headsets can be found here:

http://www.sheldonbrown.com/gloss_ha-i.html#headset

If you aren't sure if you have a quill stem, the following page has an image of a quill type stems (Technomic) and a threadless stem:

http://sheldonbrown.com/harris/stems/index.html

Thanks for the reply. My bike currently has a quill stem, but I want to convert to threadless and buy a new headset. In light of the forgoing, would I buy a fork with a 1" threadless steerer, or should I take off my current fork and measure just to be safe?

If your current bike has a 1" threaded steerer, then i'm pretty sure you need a 1" threadless steerer as well -- I don't think any other size steerer would even fit through the frame. Since you need to replace the headset as well, you'll need the gadget to remove the headset cups from the frame. They're pressed in there -- they won't just come right out. Park Tool makes a fancy gadget to pound them out, although some people have used long-handed screwdrivers and a really steady hand to slowly walk them out as well.

How badly do you want to keep your current bike frame? It's real easy to spend too much on a fork upgrade that may not mean much when you finally sell the bike. I don't want to discourage you but suggest that you consider replacing the bike instead of converting to a threadless fork system.

Al

Thanks. Just so I am clear, because my bike has a 1" headset (per the specs) that means that I must have a 1" steerer?