Give me inertia or give me death (what the heck, give me both...)

Ralph Barone invalid@not_real.ca said:

I've thrown a few pictures of my modified Minoura HyperMag trainer up at

http://members.shaw.ca/ralph.barone/Site/Bike%20stuff.html

Ralph,

How did you figure out exactly where to drill...if you care to explain
to me your balancing procedure. They do this kind of stuff on
turbocompressor impellers, but I never cared to find out how (probably
much more sophisticated techniques) 🙂

Ron
http://cozybeehive.blogspot.com

Ralph Barone invalid@not_real.ca said:

I've thrown a few pictures of my modified Minoura HyperMag trainer up at

http://members.shaw.ca/ralph.barone/Site/Bike%20stuff.html

Ralph,

That last picture (front view) looks great... thats a massive wheel.
I'm not sure what the radius is but I'm sure you already have figured
it out. Just for the records anyway check this link out for the
math :
http://www.engineeringtoolbox.com/flywheel-energy-d_945.html

You probably just wanted to have fun and do something with that "[censored]"
trainer. If I were you, I'd just sell that, and get a new Kurt
Kinetic. They already beat you to the flywheel game, with a massive 18
pounder on the shelves now. Besides, you can change flywheels pretty
easily. My two cents.

Ron
http://cozybeehive.blogspot.com

"Ron George" <[email hidden]> wrote in message
news:[email hidden]...

Ralph Barone invalid@not_real.ca said:

I've thrown a few pictures of my modified Minoura HyperMag trainer up
at

http://members.shaw.ca/ralph.barone/Site/Bike%20stuff.html

Ralph,

How did you figure out exactly where to drill...if you care to explain
to me your balancing procedure. They do this kind of stuff on
turbocompressor impellers, but I never cared to find out how (probably
much more sophisticated techniques) 🙂

I would think the heavy spot would come to rest at the bottom. It's
doubtful that lateral imbalance would be a problem on something as
uniformly constructed and as narrow as this disc. IMO eccentricity would
be the main cause of imbalance.

Phil H

In article
<[email hidden]>,

Ron George said:

Ralph Barone invalid@not_real.ca said:

I've thrown a few pictures of my modified Minoura HyperMag trainer up at

http://members.shaw.ca/ralph.barone/Site/Bike%20stuff.html

Ralph,

That last picture (front view) looks great... thats a massive wheel.
I'm not sure what the radius is but I'm sure you already have figured
it out. Just for the records anyway check this link out for the
math :
http://www.engineeringtoolbox.com/flywheel-energy-d_945.html

You probably just wanted to have fun and do something with that "[censored]"
trainer. If I were you, I'd just sell that, and get a new Kurt
Kinetic. They already beat you to the flywheel game, with a massive 18
pounder on the shelves now. Besides, you can change flywheels pretty
easily. My two cents.

Ron
http://cozybeehive.blogspot.com

Thanks for the comments. Actually, I was too cheap to buy the Kurt
Kinetic Road machine, so I just improvised what I could on my
self-imposed $40 budget.

Interestingly enough, (and as you can also figure out from the link you
posted), it's not just the mass of the flywheel, but also the ratio of
the flywheel diameter to the roller diameter that determines how much
mechanical energy is stored at a given speed. I think I calculated that
my 10", 11 lb flywheel, coupled to a slightly smaller roller, was at
least as effective as the road machine's 18 lb flywheel. I also
calculated that neither one gave as much inertia as me trying to push my
fat ass down the road either.

In article
<[email hidden]>,

Ron George said:

Ralph Barone invalid@not_real.ca said:

I've thrown a few pictures of my modified Minoura HyperMag trainer up at

http://members.shaw.ca/ralph.barone/Site/Bike%20stuff.html

Ralph,

How did you figure out exactly where to drill...if you care to explain
to me your balancing procedure. They do this kind of stuff on
turbocompressor impellers, but I never cared to find out how (probably
much more sophisticated techniques) 🙂

Ron
http://cozybeehive.blogspot.com

Balancing isn't too hard to start off with. Spin the flywheel, and if
it consistently stops in the same position, drill a hole at the bottom
to remove some mass (the heaviest bit sinks to the bottom, n'est pas?).
Repeat... If the balance point starts flip-flopping, then you're
removing too much mass, so switch to a smaller drill bit. In the end,
the bearings in the trainer had too much friction, so I put an axle
through the flywheel and sat it on a pair of parallel surfaces. Doing
that got the balance almost good enough (it still buzzes a bit at
certain speeds). If you were balancing a turbocompressor, you would use
the same basic idea, but you would use MUCH better instrumentation and
you would also ensure that it was also balanced across the length of the
shaft (look up dynamic balancing).