Frame geo/design curiosity ???'s
I'm saving up for a custom frame. It'll still be a while off before I'm ready 'cause saving is going slow.<<<**** vehicle repairs!!>>> So, in the meantime, I've been trying to educate myself on frame geometry to better understand how to get what I'd like in terms of performance, comfort, and visual appeal.....in that order. I suppose I could rely totally on a builder to account for that, but something in me would feel more comfortable in knowing exactly what's going on in the process of the design.
So, one question comes up for me that I haven't been able to get answered in my web reading. What would happen if the head tube angle were steeper than the seat tube angle?
Let's say a HT angle of 73* and a ST angle of 72*. Let's say the fork has a rake of 40mm with a wheel of approximately 675mm's in diameter. This would give a trail in the high 50's....close to 60mm's. I read that's a pretty neutral amount for handling. (I'm just giving factors that might be pertinent to my question here. Not really sure if it's important.)
Reason I ask is I don't really see any frames designed where the ST is slacker than the HT. Most frames I see have a HT and ST angle the same or the ST angle is a bit steeper than the HT. The latter particularly on smaller frames. I can understand why frames are being designed this way due to reach, wheel clearance, wheelbase, etc., but I believe I'd do well for comfort/center of gravity with a slack ST angle of at/around 72*. Also, it would reduce the effective reach for my height and body geometry relative to my usual saddle position. Eg., I could have a TT of 54 or 55cm's that would perhaps give the same effective reach of a smaller frame with a steeper ST and a TT of perhaps 53cm's.
Anyway, what do you say? Is there a problem with a slacker ST angle vs HT angle?