[python] cruzbike psi
- From: "Dirk Jan Luiting" <djl@xxxxxxx>
- To: <python@xxxxxxxxxxxxx>
- Date: Tue, 25 Apr 2006 17:32:06 +0200
Hi Doug Burton and All,
Following the pythons, i guess i left behind me my complicated positive trail
ideas.
Negative trail is just something to learn and master on the elegant python.
The same experience i share with my non python bike,
and i guess my bike is very much like your design,
except for it has no suspension at all :-( autch for the back..
and my frontend is just an old rearend stuck in the frontfork.
when i first built it and rode it, psi was very noticeble,
and as Jurgen put it, its like a swimming motion, pushing legs forward and
sideward.
the lowspeed cornering was excelent, 3 meters or so after some trying.
i never fell of. never had a whipeout. i am also a cautious driver.
stable at higher speeds to very stable.
before the swedish winter, i did some bending on the fronfork.
i guessed to make it even more stable i would have to bend the fork even more
to the back.
also the length from seat to pedal would increase, my legs are to long.
wrong i was.
the high speed stability was fine like it was,
but the lowspeed stability decreased, and thats bad, because you sit so high on
the thing,
and it becomes harder to start from standstill.
the reason i felt was that the heavy pedals wanted to fall to the ground when
taking a corner,
i guess i found out why they slightly bend the fork forwards.
also to accomodate for my legs, a put the seat back a centimeter or so.
this had an adverse effect on the psi.
furthermore to get going you will put quite some torque on the steer,
once you got going its ok, you dont compensate for the psi in that way,
all with the legs - steering - weight - back/shoulder contact with the seat.
also the weight on the front/backwheel distibution is fine.
even took rough terain once, went fine.
allthough once, with my 5 year old son on the back ~20 kg,
it wanted to wheely on the grass.
thats right, frontwheeldrive and wheely.
i could feel the wheel leaving the ground less than half the time,
less traction and less steering.
on the road though it went fine, no problems.
also had high pressure in tires, was bouncy.
so i am going to take it appart and bend it back.
i will try to get the seat more to the front,
and rotate the front driving mech. with the pedals more to the front and to the
ground.
so i quite agree that the seat is better positioned more forward towards the
pivot.
furthermore, a problem with the "taking an old bike" approach is we cant vary
the pivot angle.
but for the rest, great idea, this cruz bike.
no more pain in the butt bents.
//Dirk Jan
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