Wheel math?
1980's guy posted,
I dunno I was bored so I started poking buttons on the calculator...
I wanted to see if there was a question to be asked once you had some info...
can u think of any?
all I can think of is: "will a wheel top out(rotations per second) before a rider reaches their aero-balance speed?"
or
"on a certain run (80kmph constant hill for 5 mins tucking (6.66 km) what range of wheel sizes is most efficient and how wide is the range?"
but I don't know the physics to answer...
33mm = r
66mm = d
20cm = c
35mm = r
70mm = d
22.3cm = c
37.5mm = r
75mm = d
23.5cm = c
75mm wheel- 4200 rotations per kilometer
70mm wheel- 4480 rotations per kilometer
66mm wheel- 5000 rotations per kilometer
a 75mm wheel does 354.6 rpm at 50 km/h.
4.2 rotations per meter, and 21,276 per 50km
or
21,276 rotations in an hour, at 50km/h
21,276/60 = 354.6 rpm at 50 km/h
a 66mm wheel does 416.6 rpm at 50km/h.
5 rotations per meter, and 25000 in 50km
or
25000 rotations in an hour at 50km/h
25000/60 = 416.6 rpm at 50km/h
a 75mm wheel does 210rpm at 30km/h or 3.5 rotations/s
4.2 rotations per meter, and 12,600 per 30km
or
12,600 rotations in an hour, at 30km/h
12,600/60 = 210rpm at 30km/h
a 66mm wheel does 250rpm at 30km/h
5 rotations per meter, and 15,000 per 30km
or
15,000 in an hour, at 30km/h
15000/60 = 250rpm at 30km/h
2009 September 6 9:57 PM
1980's guy replied,
oh and I guess I should add that
75mm wheels at 50kmph do 6 rotations per second and 66mm wheels do 7
2009 September 6 10:08 PM
William Nigh the math guy? replied,
d = 1/2 (vo + vf) t
a = (vf - vo) / t
d = vot + 1/2 at2
vf2 = vo2 + 2ad
a= acceleration d= distance vf= final velocity vo= initial velocity t= time
for kinematic problems involving a constant acceleration those are the only equations you need