Originally Posted by
IvyCap
I'm a little confused on the whole subject of trail in relation to headtube angles and fork rake. First question, do the leg lengths change from different rakes? For instance will the toptube level differ from rake to rake (sloped forward, or backward based on a horizontal toptube).
And as far as track racing goes, what seems to be an appropriate range for trail? From what I got on this article something +/- of 60mm of trail is ideal?
Thanks in advance!
It is my understanding that the net fork length doesn't change with the offset/rake as illustrated in the diagram as 368mm. So, swapping out forks should leave the top tube horizontal. The wheel just moves forward or backward a bit.
60mm isn't ideal for all situations...also as illustrated in the article. Sprint bikes (like the LOOK 496 and Dolan DF3) seem to have settled on 74.5 degree head tubes with 30-35mm rake forks. Pursuit bikes (like the LOOK
596 and Felt TK1) have 40mm rake forks. This makes the pursuit bikes more stable when in aerobars.
Basically, there are 3 types of bikes for track racing:
- Pursuit
- Mass Start (all-around)
- Sprint
Mass start bikes have a neutral geometry. Pursuit is more slack and wants to track a straight line. Sprint bikes are more aggressive and feel like they can turn on a dime.