Understanding Torque - Page 3

lovehamr · #41 (**permalink**) 01-31-2018, 07:10 PM

Mike, I got to check out the Motus bikes at Jekyll island a while back and if there is any way I can swing it, it will be my next bike.

olddog · #42 (**permalink**) 02-02-2018, 06:33 PM

Quote:

Originally Posted by jon@harrison.ne

As a PhD in Mechanical Engineering I can't resist commenting on this statement by Old Dog, who otherwise made a lot of correct statements. HP is simply one commonly used unit of power and has nothing to do with whether it is produced in linear or rotational motion. For example, a solid rocket engine has no rotational parts, in fact it has no moving parts of any kind, but it sure can have a lot of power, which we can express in HP, watts, Btu/min.,....

True. 1 Hp is also defined to be 745-ish watts. So indeed, you can measure your electric bill in Hp if you wanted to. And, you could convert the Btu rating of your furnace to Hp, as well. Yes in a true technical definition Power is Power, however in the real world Hp is used to rate engines and motors.

So saying Hp is associated with rotation, although it is not technically correct, in reality it is about the only time that unit of measure is ever used in the real world. For my intended purpose I might argue close enough, however I started down this road complaining about someone else miss stating and confusing the issue, so I stand corrected.

I'm a bit disappointed that you just tossed that out and moved on without adding much to the subject at hand, as I suspect you could easily do so, much more eloquently than myself.

mikeinatlanta · #43 (**permalink**) 02-02-2018, 09:24 PM

Solid point olddog. Thinking I'll convert all power makers and users in my house to hp, cause I like hp better than anything else (even beer). Not too sure how much hp to assign for the wife though. I mean I can make sense of her motion and torque potential, just not educated enough to factor in the friction.

Jaydee · #44 (**permalink**) 02-02-2018, 10:53 PM

Just curious of how much hp a person can produce?
JD

Dominik · #45 (**permalink**) 02-03-2018, 06:10 AM

A good cyclist can produce 1.2 kW.

strictlypersonl · #46 (**permalink**) 02-03-2018, 06:36 AM

Quote:

Originally Posted by Dominik

A good cyclist can produce 1.2 kW.

That's only for short bursts.
I'd be lucky to sustain 0.25kW (0.3 HP) for more than a minute. (Although I'm definitely not a "good" cyclist.)

Dominik · #47 (**permalink**) 02-03-2018, 08:56 AM

A spri(n)ter can even go higher. My limit is also approx 250 Watt during an EEG.
But how much torque is 1 kW with a 170 mm crank on the bike? :-) (Back to the topic?)

And what role do 70 rpm play?

;-)

patrickt · #48 (**permalink**) 02-03-2018, 11:47 AM

Quote:

Originally Posted by Dominik

A spriter can even go higher. My limit is also approx 250 Watt...
;-)

Yep, every Sprite I've ever driven seemed like it was putting out about a light bulb's worth of power.

olddog · #49 (**permalink**) 02-03-2018, 04:02 PM

Quote:

Originally Posted by Dominik

A good cyclist can produce 1.2 kW.

1.6 Hp for Mike.

So, it's possible to go over 25 mph on a bicycle with only 1.6 Hp? Hmm... Never gave it any thought.

patrickt · #50 (**permalink**) 02-03-2018, 04:20 PM

Quote:

Originally Posted by olddog

So, it's possible to go over 25 mph on a bicycle with only 1.6 Hp? Hmm... Never gave it any thought.

Well, yeah... down hill.

strictlypersonl · #51 (**permalink**) 02-03-2018, 04:28 PM

Quote:

Originally Posted by olddog

1.6 Hp for Mike.

So, it's possible to go over 25 mph on a bicycle with only 1.6 Hp? Hmm... Never gave it any thought.

Actually, there are many bikes with 750 watts that will easily do that. They are usually governed to 20 mph (I think that's a law), but it's an artificial limit. A little tweaking yields over 30 mph.