Thanks for going to the trouble of copying your notes and your helpful remarks!
Originally Posted by
Andrew R Stewart
I certainly agree that trail isn't the only main factor at play in defining handling. The steering geometry isn't the complete picture either. Weight distribution as defined by front and rear (chain stay) centers as well as seat set back with bar reach/height are also strong factors.
Yes I think weight dist is huge. On the specific 20" wheeled bike i'm unhappy with my handlebars are level with my saddle - which is a comfortable position but I think adds to my feelings of instability. Jan Heine, Editor, Bicycle Quarterly says: "More important is your riding position. If you sit more upright, you have less weight on the handlebars, thus less wheel flop, and so you should have more trail."
Originally Posted by
Andrew R Stewart
As to steering geometry in general I'll pass along what both Bill Boston and Georgena Terry have followed and add my opinion/numbers.......What this means for 20" wheels? I'm not sure but if I had zero foundation I would look at the castor of 80*-81* and see where that puts rake/trail then look at published data and if at all possible test ride bikes that mimic known data.
Thanks. This is a new use of castor angle to me. I get the sense that you use it mostly to double check your other settings to make sure it's going in the direction you want it to go. I calculated the castor angle on the bike in question and got 82.1° - well on the wrong side of "neutral".
Originally Posted by
Andrew R Stewart
What this means for 20" wheels? I'm not sure but if I had zero foundation I would look at .... published data and if at all possible test ride bikes that mimic known data.
Unfortunately most companies building bikes with 20" wheels (most of which are folding) don't publish their geometry figures and so what we're left with is subjective impressions and mythology.
Tom