Originally Posted by
Wildwood
Hey - i'm going to use this empty Pub as a staging 'post' for a future C&V thread. About fork curvature on steel forks. Pull together a few pics, see if it makes sense tomorrow. Please don't spill your beer on my notes.
Comments welcome. i may edit this post more than a couple of times.
The purpose of the post is to help me understand the handling characteristics of a particular bike. An early 70s Zeus brazed in Erbil, Spain - deep in the Basque region. Look at attached pics and tell me if you think this fork curvature is different from most on a (vintage lightweight) sport/racing bike. And would it yield a more 'touring' feel in the front end steering? Or is it just a French (+Basque) design? Would the unknown (to me) fork material be responsible for perceived ride(main tubes are 531)? Or should I just ride a wider range of bicycles and not obsess over any outliers.
Zeus
And here is a fork bend, also from the early 70s, that may deliver a different feel than the Zeus.
Hmmmnn... maybe the 2 pics below show the difference between fork bends better.
And below is my early 70s French touring frame, tho a slightly larger size. The Follis has a bend more like the Bottechia in my estimation.
The first key point about these forks is to compare their offsets - the distance from the wheel axle center to the projection of the steering axis, measured perpendicular to the steering axis. Second is the steering axis angle from either perpendicular or horizontal. Those two parameters plus the wheel diameter let you calculate trail, which is a key indicator for bike handling. The radius of curvature and the outer diameter of the fork blade where it is curved are key to estimating ride quality. It also is affected by tubing wall thickness, but I'm not sawing apart any vintage forks to find that answer.