Discussion in 'Fitness & Nutrition' started by Leo95SE, Mar 9, 2006.
is there a consistent calculation that can be used?
the only numbers ive seen are 55rpm = 15mph.
you would need the radius of the tire.
arent they standard for stationary bikes?
Maybe, but who the fuck knows that kind of shit?
not up to bringing a tape into a gym and measuring while someone is staring down at me.. lol
id just assume they were all the same.
someone go ride a stationary bike and tell me what it says
The bikes at my gym show both?
Figure out what type it is and look on the manufacturers webpage. They should list it under specs.
thas the site i used
went there. precor - nuttin .
btw, correct formula?
circumference = pi*d
4' tire (!!!) = 150" circumference
tire travels (you move) 150" in one rev. (12.5ft)
so, 80rpm * 12.5' = 1000ft/min, or 11.3mph
sorry most ppl dont measure circumference, but diameter. i just misread.
however, i dont think you calc'd right, did you?
4' cir = 3.6mph from my retard calcs.
Well, it would depend on what resistance you have it on. Since those levels effectively serve as gears do on a normal bike, speed will be related to more than just RPM.
I think it's way more effort to figure this out than what it's worth.
resistance is changed by the tightening of the belt around the wheel. why would that play a factor in distance travelled? wouldnt that be work performed?
tighter belt(gearing) means more work, or slower rpm, but still same conversion of rpm to mph, whether slow or fast..
Do whatever the fuck you guys want, I'm just telling you that every single bike I've been on will factor in your resistance level when calculating the speed.
another approach is considering resistance level, and using an arbitrary formula to calculate rpm/speed based on some predetermined ratio.
ill get to the bottom of this..
i did that. data not avail. ill contact manufacturers when i have some free time.
Well if you think about it, you can do 100 peddle rpms and only go 5mph on a bike in first gear, or you can do 100 peddle rpms in 27th gear (or whatever the fuck bikes go up to these days) and be doing 35 mph. The difference is going to be the resistance of the peddle to the force generated by your feet. And although there is no real way to recreate this on a stationary (mainly because you can't freewheel like you can on a road bike) it would be more appropriate if you considered your speed as increasing as your resistance increased (assuming the same peddle rpms).
Thx. My point exactly.
And furthering my argument that you are going to drive yourself insane trying to figure this out.
this is a good point, power would have to increase if resistance increased to maintain rpm. (common sense, huh?)
i was hoping to avoid the calculated gearing on the bike but i dont think you can. not for the direct reason that seems obvious, but b/c i think the display generates some calculated rpm/mph based on a programmed resistance, or assumed wheel diameter. since you essentially arent really moving, it has to make up one of these variables, i think.
'real' bike gearing is like 1:1, 1:2, etc. im guessing stationary bikes have to assume one of these ratios for the formula to work, AND, since you have to input weight (and if you change it, notice the other variable change as well), this also plays some odd factor in the calc.
either way, all guesswork at this point. ill see if any of the manufacturers can provide me with some good info.
fine with me, i enjoy it. it was obviously created an entered into some sort of plc or microchip so that means theres an answer. im sure the answer will have no bearing at all though, it will be completely arbitrary, and the time/distance spent on a stationary bike will wind up not related at all to real ones. (im not talking wind resistance, terrain, etc either)
The bikes at my gym show both and when I go 90 rpm it says it is around 11 mph.
I'm a bit of a biker, and while I've never been on a stationary at a gym. I've been riding my bike on my trainer a lot over this winter. Really your rpm is not very translatable at all to what your speed is gonna be out on the streets.
Your best bet is just finding the highest resistance which you can hold about 90+rpm. You'll see your speed/endurance on the streets increasing a lot, especially if your new.