Inertia maths help

On 1/30/2011 2:56 AM, Joseph Santaniello wrote:
--
Tºm Shermªn - 42.435731,-83.985007
I mistook the hyphen for an unary operator and thought to myself, Good
God, where has Tom moved to now?!?


Yes, that would put me in the Pacific Ocean a few hundred km from the
Chilean coast.

--
Tºm Shermªn - 42.435731,-83.985007
I am a vehicular cyclist.

On Jan 30, 3:28*pm, Tºm Shermªn™ °_° ""twshermanREMOVE\"@THI
$southslope.net" wrote:
On 1/30/2011 2:56 AM, Joseph Santaniello wrote:

--
Tºm Shermªn - 42.435731,-83.985007
I mistook the hyphen for an unary operator and thought to myself, Good
God, where has Tom moved to now?!?

Yes, that would put me in the Pacific Ocean a few hundred km from the
Chilean coast.


Clearly taken with a big zoom to catch the distant coast:

http://www.marinadelsur.info/images/...paddleboat.jpg

One important consideration is the friction you will need to keep the
tire from spinning on the roller. IME it takes a lot of pressure.

On Jan 30, 11:00*pm, Ron Ruff wrote:
One important consideration is the friction you will need to keep the
tire from spinning on the roller. IME it takes a lot of pressure.

I already use 3M friction tape, which seems to work very well. It
remains to be seen once the inertia of the FW is increased tenfold...

On Jan 29, 7:24*pm, Joseph S wrote:
On Jan 29, 7:30*pm, Lou Holtman wrote:



Op 29-1-2011 18:03, Joseph S schreef:

On Jan 29, 3:39 pm, Dave *wrote:
Joseph S wrote:

Well, I'm at least amusing myself here... radius of the roller, not
diameter...

Joseph

I'm probably at fault for the confusion, since I mentioned the ratio of
diameters in the text, but then used the ratio of radii in the
calculation. The ratio is the same, but radius is easier to use in other
parts of the calculation, which is why I used that.

I don't have time to check your calculations before my ride this
morning, but I'll do a calculation for my CycleOps trainer and see what
I come up with later today.

Dave Lehnen

Have a nice ride!

I can't get the numbers to make any sense. Using the roller radius
(instead of diameter), I end up with a desired total inertia of .
000586 which is even less.

.335m wheel radius
.0275m roller radius
115kg effective mass

Joseph

Just go ride outside, saves you a lot of worries. ;-)

Lou, bright sunshine at 1 degree Celcius today.

I did ride outside today! Bright sunshine, -6C. I use the Kurt for
sprint workouts, which I can't do on ice...

Joseph

Get a pair of ice tyres. You might not be the first to do it but
there sure won't be many others considering that training today
(except maybe in Belgium). Working on ice should make you smoother
because if you overtorque at any point you will still unstick the rear
wheel. BTW you should be doubling that gentle cruising speed at least
or you're using the wrong gear ratio.

On Jan 31, 2:27*pm, thirty-six wrote:
On Jan 29, 7:24*pm, Joseph S wrote:





On Jan 29, 7:30*pm, Lou Holtman wrote:

Op 29-1-2011 18:03, Joseph S schreef:

On Jan 29, 3:39 pm, Dave *wrote:
Joseph S wrote:

Well, I'm at least amusing myself here... radius of the roller, not
diameter...

Joseph

I'm probably at fault for the confusion, since I mentioned the ratio of
diameters in the text, but then used the ratio of radii in the
calculation. The ratio is the same, but radius is easier to use in other
parts of the calculation, which is why I used that.

I don't have time to check your calculations before my ride this
morning, but I'll do a calculation for my CycleOps trainer and see what
I come up with later today.

Dave Lehnen

Have a nice ride!

I can't get the numbers to make any sense. Using the roller radius
(instead of diameter), I end up with a desired total inertia of .
000586 which is even less.

.335m wheel radius
.0275m roller radius
115kg effective mass

Joseph

Just go ride outside, saves you a lot of worries. ;-)

Lou, bright sunshine at 1 degree Celcius today.

I did ride outside today! Bright sunshine, -6C. I use the Kurt for
sprint workouts, which I can't do on ice...

Joseph

Get a pair of ice tyres. *You might not be the first to do it but
there sure won't be many others considering that training today
(except maybe in Belgium). *Working on ice should make you smoother
because if you overtorque at any point you will still unstick the rear
wheel. *BTW you should be doubling that gentle cruising speed at least
or you're using the wrong gear ratio.

I do more than enough on ice with studded tires. And I agree is is
nice practice for keeping smooth, but no way I'm letting loose with
2000W on it ;-)

This FW stuff is for full-gas sprints. And usually I do my jump from
40-45 km/h. I've tried from faster, but I'm more of an explosive type
than a fast wind-up type.

On Jan 31, 3:25*pm, Joseph S wrote:
On Jan 31, 2:27*pm, thirty-six wrote:



On Jan 29, 7:24*pm, Joseph S wrote:

On Jan 29, 7:30*pm, Lou Holtman wrote:

Op 29-1-2011 18:03, Joseph S schreef:

On Jan 29, 3:39 pm, Dave *wrote:
Joseph S wrote:

Well, I'm at least amusing myself here... radius of the roller, not
diameter...

Joseph

I'm probably at fault for the confusion, since I mentioned the ratio of
diameters in the text, but then used the ratio of radii in the
calculation. The ratio is the same, but radius is easier to use in other
parts of the calculation, which is why I used that.

I don't have time to check your calculations before my ride this
morning, but I'll do a calculation for my CycleOps trainer and see what
I come up with later today.

Dave Lehnen

Have a nice ride!

I can't get the numbers to make any sense. Using the roller radius
(instead of diameter), I end up with a desired total inertia of .
000586 which is even less.

.335m wheel radius
.0275m roller radius
115kg effective mass

Joseph

Just go ride outside, saves you a lot of worries. ;-)

Lou, bright sunshine at 1 degree Celcius today.

I did ride outside today! Bright sunshine, -6C. I use the Kurt for
sprint workouts, which I can't do on ice...

Joseph

Get a pair of ice tyres. *You might not be the first to do it but
there sure won't be many others considering that training today
(except maybe in Belgium). *Working on ice should make you smoother
because if you overtorque at any point you will still unstick the rear
wheel. *BTW you should be doubling that gentle cruising speed at least
or you're using the wrong gear ratio.

I do more than enough on ice with studded tires. And I agree is is
nice practice for keeping smooth, but no way I'm letting loose with
2000W on it ;-)

This FW stuff is for full-gas sprints. And usually I do my jump from
40-45 km/h. I've tried from faster, but I'm more of an explosive type
than a fast wind-up type.

So Ok you can't buy a production flywheel of the correct weight right
now and you want to get on with training quickly, how about using a
steel rimmed wheel and use double sided tape to stick on the inner
face of the rim some lead sheet cut into strips. Balance the now
heavy wheel as best you can, preferably dynamically. If you are still
hitting your top speed within about six seconds, add some more lead.
Eventually you will be loading more than the equivalent of shifting
your own mass. I've no idea how much lead you will need or how well
this would suit, but at least it offers a quick solution which may be
better in the long term without too much investment. A slight
overload is always best for training (as in no banking) so dont
overweight the wheel or you will lose your spin.

On Jan 31, 5:48*pm, thirty-six wrote:
On Jan 31, 3:25*pm, Joseph S wrote:





On Jan 31, 2:27*pm, thirty-six wrote:

On Jan 29, 7:24*pm, Joseph S wrote:

On Jan 29, 7:30*pm, Lou Holtman wrote:

Op 29-1-2011 18:03, Joseph S schreef:

On Jan 29, 3:39 pm, Dave *wrote:
Joseph S wrote:

Well, I'm at least amusing myself here... radius of the roller, not
diameter...

Joseph

I'm probably at fault for the confusion, since I mentioned the ratio of
diameters in the text, but then used the ratio of radii in the
calculation. The ratio is the same, but radius is easier to use in other
parts of the calculation, which is why I used that.

I don't have time to check your calculations before my ride this
morning, but I'll do a calculation for my CycleOps trainer and see what
I come up with later today.

Dave Lehnen

Have a nice ride!

I can't get the numbers to make any sense. Using the roller radius
(instead of diameter), I end up with a desired total inertia of

Joseph S wrote:
On Jan 31, 5:48 pm, wrote:
snip

So Ok you can't buy a production flywheel of the correct weight right
now and you want to get on with training quickly, how about using a
steel rimmed wheel and use double sided tape to stick on the inner
face of the rim some lead sheet cut into strips. Balance the now
heavy wheel as best you can, preferably dynamically. If you are still
hitting your top speed within about six seconds, add some more lead.
Eventually you will be loading more than the equivalent of shifting
your own mass. I've no idea how much lead you will need or how well
this would suit, but at least it offers a quick solution which may be
better in the long term without too much investment. A slight
overload is always best for training (as in no banking) so dont
overweight the wheel or you will lose your spin.

That's a good idea. I think I would need to add about 1.4 kg lead to
the rim to get the correct inertia. Have to make sure it is well
fastened...

Static balancing would be pretty easy, since the actual weight isn't
critical, I could just shave off bits here and there.

Unfortunately, without the increase in effective moment of inertia
provided by the fact that the trainer spins much faster than the rear
wheel, this isn't a practical idea. The weight you would need to add to
the rim would be in the neighborhood of your own weight.

Dave Lehnen

On Jan 31, 5:21*pm, Dave Lehnen wrote:
Joseph S wrote:
On Jan 31, 5:48 pm, *wrote:
snip

So Ok you can't buy a production flywheel of the correct weight right
now and you want to get on with training quickly, how about using a
steel rimmed wheel and use double sided tape to stick on the inner
face of the rim some lead sheet cut into strips. *Balance the now
heavy wheel as best you can, preferably dynamically. *If you are still
hitting your top speed within about six seconds, add some more lead.
Eventually you will be loading more than the equivalent of shifting
your own mass. *I've no idea how much lead you will need or how well
this would suit, but at least it offers a quick solution which may be
better in the long term without too much investment. *A slight
overload is always best for training (as in no banking) so dont
overweight the wheel or you will lose your spin.

That's a good idea. I think I would need to add about 1.4 kg lead to
the rim to get the correct inertia. Have to make sure it is well
fastened...

Static balancing would be pretty easy, since the actual weight isn't
critical, I could just shave off bits here and there.

Unfortunately, without the increase in effective moment of inertia
provided by the fact that the trainer spins much faster than the rear
wheel, this isn't a practical idea. The weight you would need to add to
the rim would be in the neighborhood of your own weight.

Dave Lehnen

Yes, wrong units. A pound on the wheels is worth two on the bike,
which indicates half body weight. But, there is already a flywheel
there absorbing some of the energy of acceleration so th... It
might be better to consider what is the practical limit of lead
loading a rim and see where that takes the problem.