Join Date: Feb 2005
Bikes: Trek 5500, Colnago C-50
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The bike has a nice classic look now, are you sure you want to pimp it up with a "modern" fork?
A little more information would be nice, I assume you now have 27" wheels and are considering 700mm wheels and a fork with a threadless steerer? When changing wheel sizes the first thing to consider is if the brake pads can be adjusted to fit the new rim or if you will also need new brake calipers.
The fork leg length does have some effect on handling but the difference between the length of a 27 fork and a 700 fork shouldn't make a huge difference, leg lengths vary from make to make even within the 700 size forks. The fork's rake may make a more noticeable difference and rake is not necessarily related to leg curvature because rake on straigter legged forks is controlled at the crown by the angle between the steer tube and fork leg. A straight fork can have as much or more rake than a curved fork. Steering response is effected mostly by trail, and trail is a function of head tube angle, wheel size, and fork rake. A change in fork leg length effectively changes head tube angle. If you shorten the legs you lower the front of the bike the steepening the HTA and shortening trail. If that fits your case you could compensate by using a fork with a shorter the rake which in turn will increase trail.
Here is a link to a rake and trail calculator I like to use to compare forks. It does not allow for an independent calculation of a fork leg length change but that could be done by tweaking the HTA input. The calculator is set up to run using inch or cm parameters. You can make the same calculations using basic trigomometry.
Last edited by Al1943; 05-27-05 at 10:14 AM.