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View Full Version : bike geometrie and force's


ada@prorider.or
05-15-2005, 04:56 PM
has ony one a program wher you can calculate a bike geometri given to human size but also with the force's is generate when it moving giving all other weight's and moving parts
so after the calc is done you come to the stability figure of =0

meaby a aero engineer here who bike's


(as you see a idiot like i am can ask more stupid question's then a inteligent one can answer)

jerk
05-15-2005, 05:18 PM
cees-
the complexity of the math required to replicate the thousands of forces present when a human body is cycling would be very tough to achieve. there is a proof out there somewhere whereby a stanford professor (the jerk thinks) tried to mathematically explain the ability of a bicycle rider to propel a bicycle forward while maintaining balance....he admitted failure. and that would seem alot simpler.

the colllective experience of frame builders and bicycle racers has boiled down to cetain parameters of proper frame design and bike fit. these are explained in the coni manual among other places that you are familiar with. nonetheless, this is really based more on experience, oral traditionan and even a little superstition.

wattage meters and wind-tunnels should have provided a quantum leap forward in bicycle positioning and design. the fact that they didn't (outside of tt bike design) points to the fact that cinelli, masi et. al probably had it pretty close to right.

there's a lot of stupid sizing programs out there. no one to the jerk's knowledge, has produced the type of software you describe. there have been attempts to pool the information on fit and performance from large groups of cyclists...but this is really only a different itteration of what accomplished frame builders hav done for decades. just because the info is on a computer and not in a framebuilder's note book, doesn't make it any more scientific or high tech. fit and positioning on raceing bicycles still relies on feel and non-tangible experiences of both athletes and framebuilders rather than any objective science......

the industry that has people designing bicycles who can't even define trail, is no where near ready to emabarl on the challange you offer.

ada@prorider.or
05-15-2005, 05:24 PM
cees-
the complexity of the math required to replicate the thousands of forces present when a human body is cycling would be very tough to achieve. there is a proof out there somewhere whereby a stanford professor (the jerk thinks) tried to mathematically explain the ability of a bicycle rider to propel a bicycle forward while maintaining balance....he admitted failure. and that would seem alot simpler.

the colllective experience of frame builders and bicycle racers has boiled down to cetain parameters of proper frame design and bike fit. these are explained in the coni manual among other places that you are familiar with. nonetheless, this is really based more on experience, oral traditionan and even a little superstition.

wattage meters and wind-tunnels should have provided a quantum leap forward in bicycle positioning and design. the fact that they didn't (outside of tt bike design) points to the fact that cinelli, masi et. al probably had it pretty close to right.

there's a lot of stupid sizing programs out there. no one to the jerk's knowledge, has produced the type of software you describe. there have been attempts to pool the information on fit and performance from large groups of cyclists...but this is really only a different itteration of what accomplished frame builders hav done for decades. just because the info is on a computer and not in a framebuilder's note book, doesn't make it any more scientific or high tech. fit and positioning on raceing bicycles still relies on feel and non-tangible experiences of both athletes and framebuilders rather than any objective science......

the industry that has people designing bicycles who can't even define trail, is no where near ready to emabarl on the challange you offer.

well the thing is not so complicated as you define
i have a forumula thats define's it
learn it my bike school
also i do evertime everything in a complex cad program
everytime everything by hand
and the program is the most advanced
but still its not designed for bike's
so its always a lot of work
and you have to keep you mind to it
but i search a program that does all those things for me

Matt Barkley
05-15-2005, 05:31 PM
I think the complexity of the human body - and the fact that no 2 different people move the same way would make these equations near impossible (IMveryHO). How one "sits" on a bike and makes it move forward can be a beautiful thing - albiet and art and science of propulsion.

What size bike you ride and yer' position changes (over time - for many reasons) you improve - or get worse' - it is dynamic (the human body is dynamic)

Agreed with Jerk on this one - the watts and windtunnels you'd think would help out - hasn't in my not humble opinion. TT bikes being the exception.

I think riders "looked" the best and were most fluid early 90s - before compact geos, etc. (Sorry for the change in subject)

Hmm... What should I drink tonight? :beer: - Matt

ada@prorider.or
05-15-2005, 05:37 PM
I think the complexity of the human body - and the fact that no 2 different people move the same way would make these equations near impossible (IMveryHO). How one "sits" on a bike and makes it move forward can be a beautiful thing - albiet and art and science of propulsion.

What size bike you ride and yer' position changes (over time - for many reasons) you improve - or get worse' - it is dynamic (the human body is dynamic)

Agreed with Jerk on this one - the watts and windtunnels you'd think would help out - hasn't in my not humble opinion. TT bikes being the exception.

I think riders "looked" the best and were most fluid early 90s - before compact geos, etc. (Sorry for the change in subject)

Hmm... What should I drink tonight? :beer: - Matt

the wonder of the new cad software is that you can calculate all those things a find a optimum for that moment
you can put all forces in it and calc