When building a bike from scratch, you may have to mess around with these angles in order to get your ride tuned exactly the way you like it, and you will quickly find out that there is no magic rule to getting it right without a little experimentation.
Figure 2 - Rake and trail defined
Short wheelbase recumbents, like our HighRoller pictured in Figure 3 have a wheelbase often close to that of a typical upright bicycle, so head tube angle, rake and trail are often close to the same typical measurements. When I built the HighRoller, I used the exact same head tube angle, rake, and trail measurements that I took from the donor cycle, and the ride is very smooth, even with no hands! The shorter the wheelbase, the more that head tube angle and rake seem to affect the ride, so be careful when making adjustments as sometimes only a few degrees in either direction will achieve the result you are looking for.