Turbo Trainer advice needed

In article <[email hidden]>, [email hidden] says...

Quoted message said:

Folks, I am looking for a turbo trainer and have read conflicting reports about which is the best
type, magnetic or fluid? My friends says fluid TT's are the way to go, others say they is too heavy
and only suitable for hill-climb training. Any opinions? Recomendations on a good make? (I want to
get a decent model, but not spend the earth)

IIRC, fluid resistance increases as you go faster, just like riding in the real world. Mag
resistance is constant.
-----------------
Alex __O _-\<,_ (_)/ (_)

Quoted message said:

says...

Quoted message said:

Folks, I am looking for a turbo trainer and have read conflicting reports about which is the best
type, magnetic or fluid? My friends says fluid TT's are the way to go, others say they is too

heavy

Quoted message said:

Quoted message said:

and only suitable for hill-climb training. Any opinions? Recomendations on a good make? (I want
to get a decent model, but not

spend

Quoted message said:

Quoted message said:

the earth)

IIRC, fluid resistance increases as you go faster, just like riding in the real world. Mag
resistance is constant.
-----------------

Not sure about that. If mag resistance works by spinning a disc through a magnetic field then
doubling the disc speed will double the induced voltage and pretty much double the induced current.
This current flows in a direction that causes a force in opposition to the change inducing it. So
doubling the induced current will double the resisistive force.

As work done = force x distance and power = work done/time

You get power = (force x distance)/time.

Consider doubling your cadence;

In any given time interval you will double your distance, the force of opposition has also doubled.
This will double double the power.

Doubling cadence requires you to work 4 times harder.

Assuming mag resiatnce works on the generator principle.

John

p.s. aerodynamic drag increases in the same way in the real world.

I use a Travel-Trac 2000 fluid trainer and like it as much as it is possible to like such a thing.
Best of all is that it is quieter than the air trainer I built. I can watch TV or listen to music
without the volume maxxed.

"Adam Lipscombe" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

Folks,

I am looking for a turbo trainer and have read conflicting reports about which is the best type,
magnetic or fluid?

My friends says fluid TT's are the way to go, others say they is too heavy and only suitable for
hill-climb training.

Any opinions? Recomendations on a good make? (I want to get a decent model, but not

spend

Quoted message said:

the earth)

TIA - Adam

The question of trainers sometimes comes up on the power list (topica.com/wattage, I think).

There is a page referenced in some posts there that shows speed-to-power curves for various
trainers. Link: geocities.comtrainerpowerOpen ↗

Basically, any trainer that can reach the power you wish to train at within the speed range you can
get with your gears is okay. The difficult case is if you try to simulate "hill climbing", where
resistance must be high, but cadence (and thus speed) is typically low.

Generally, they all get harder with increasing speed. Some more steely than others. The mag ones are
generally not as steep, and some with switches don't have a consistent rate of increase.

There is argument whether matching "real life" is a benefit. Most prefer it, but many can't say why.

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

Quoted message said:

Quoted message said:

says...

Quoted message said:

Folks, I am looking for a turbo trainer and have read conflicting reports about which is the
best type, magnetic or fluid? My friends says fluid TT's are the way to go, others say they
is too

heavy

Quoted message said:

Quoted message said:

and only suitable for hill-climb training. Any opinions? Recomendations on a good make? (I want
to get a decent model, but not

spend

Quoted message said:

Quoted message said:

the earth)

IIRC, fluid resistance increases as you go faster, just like riding in the real world. Mag
resistance is constant.
-----------------

Not sure about that. If mag resistance works by spinning a disc through a magnetic field then
doubling the disc speed will double the induced voltage and pretty much double the induced
current. This current flows in a direction that causes a force in opposition to the change
inducing it. So doubling the induced current will double the resisistive force.

As work done = force x distance and power = work done/time

You get power = (force x distance)/time.

Consider doubling your cadence;

In any given time interval you will double your distance, the force of opposition has also
doubled. This will double double the power.

Doubling cadence requires you to work 4 times harder.

Assuming mag resiatnce works on the generator principle.

John

p.s. aerodynamic drag increases in the same way in the real world.

I have an Elite Travel Fluid for sale if you are interested? Have only used it twice as now I
commute every day. It was bloody cold this morning on the way in!!

Cheers

Steve

"Adam Lipscombe" <[email hidden]> wrote in message
news:<[email hidden]>...

Quoted message said:

Folks,

I am looking for a turbo trainer and have read conflicting reports about which is the best type,
magnetic or fluid?

My friends says fluid TT's are the way to go, others say they is too heavy and only suitable for
hill-climb training.

Any opinions? Recomendations on a good make? (I want to get a decent model, but not spend
the earth)

TIA - Adam

I have two turbo trainers. One is a Cateye Cyclosimulator (popularly known as the PsychoStimulator
:-) ). This is the turbo I do serious training on. It has a bit more to occupy the brain, in terms
of speed, power, etc. It has a fan, which increases the effort/unit speed as speed increases, and a
magnetic load to simulate gradient. The tyre roller is spring loaded against the tyre, so it copes
with slightly non-round wheels quite well. A nice machine.

The other one I have is a budget Tacx turbo, bough principally to take to races for warming up. This
one has a magnetic load on it. The biggest downside is that the roller isn't sprung against the
tyre, and it seems to me that this tends to make the pedalling action quite choppy.

Other than those observations, for serious training you definitely need something that will let you
adjust the resistance. Fluid trainers seem popular among my clubmates.

Oh, and figure out some way to keep the sheets of sweat off the bike!

Robert

The mags I've measured are a waste of time if you want to train at high power (or need moderate
power at low speed). Compared to wind or fluid trainers I've measured, mags just don't generate
that much resistance, and they take some fairly high speed to generate the moderate resistance they
*do* reach.

If you just want to do "grandma" work outs, a mag unit is fine. Or just get rollers :-)

geocities.comtrainerpowerOpen ↗

[email hidden] (Jon Isaacs) wrote in message
news:<[email hidden]>...

Quoted message said:

Quoted message said:

Not sure about that. If mag resistance works by spinning a disc through a magnetic field then
doubling the disc speed will double the induced voltage and pretty much double the induced
current. This current flows in a direction that causes a force in opposition to the change
inducing it. So doubling the induced current will double the resisistive force.

This topic was addressed extensively in a thread last year. I did some measurements using my
PowerTap of the drag of my Minora Mag trainer at various speeds.

While it is not power vs speed is not quite linear, it is quite close to linear indicating that
the drag is nearly constant. Sometime late in the thread, Andrew Coggan pointed out that Chet Kyle
had some tests and gotten the same results. There was an explanation of the reason for this which
I have forgotten, some sort of saturation+thermal equilibrium.

Regarding simulation of climbing vs flat:

Climbing, the retarding force is approximately constant, at speed on the flat is is higher order.

The one thing that no trainer can simulate (or at least no trainer I know of) is the inertial
effects. In my view this is what really makes the feel of pedalling on the road. When you push on
the pedals on the road, you have an inertial resistance to accelleration which is huge,
essentially a function of your mass and the bicycles mass. If you push twice as hard, your
increase your speed twice as fast, which is still not a big differential in velocity.

But on a trainer, there is not mass so a hard push spins everything up in but a second or two.

IN my view, that inertial resistance to acceleration is the first order characteric of pedalling a
bicycle and simulating the mass of 150 lbs (actually
4.66 slugs) or more of a rider and bike is really impossible.

One could use a heavy rear wheel, but it would have to be very heavy because the inertia a wheel
going the velocity of interest with all the mass at the edge would have to have the same mass as
the bike/rider combination.

Bottomline: Just get a mag trainer. THey are cheap, they are quiet and they are reliable.

Jon Isaacs

[email hidden] (Jon Isaacs) wrote in message
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Quoted message said:

Quoted message said:

The mags I've measured are a waste of time if you want to train at high power (or need moderate
power at low speed).

This morning it just so happened that someone (Damon Rinard) had Emailed me about this very issue.
So, before leaving for work, I put my bike with the Powertap on my Mag trainer and would it up to
see how much power I could put out. Unfortunately the tire was slipping but I still managed 1225
watts, not too bad for a maximum effort with no warm up.

Wow! That's pretty cool! What model mag trainer is it?

On various wind and fluid trainers I've tried I've seen about 400W regularly, but only about
900W maximum.

Also, what RPM did you have to spin to make that kind of power?

Quoted message said:

So, I guess if you need to train at levels higher than probably 1000 watts for extended periods of
time, a mag trainer may not work for you.

The two mag trainers I've tried I couldn't reach 400W no matter fast I went (in one case over
90 km/h!).

The main problem is when I am trying to simulate hills, which not everyone might want to do. If I'm
standing for several minutes, my speed (rpm) is limited. (That's true for me on long climbs on the
road, too.) That's when the mag units I've tried can't generate the resistance that simulates the
hills like I want it to, even in my biggest gear.

Quoted message said:

Quoted message said:

If you just want to do "grandma" work outs, a mag unit is fine. Or just get rollers :-)

My gramma always had a hard time maintaining more than 500 watts for more than an hour or two. :-)

LOL! Was her name Linda Armstrong? ;-)

Quoted message said:

jon isaacs

"dianne_1234" <[email hidden]> wrote in message
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Quoted message said:

[email hidden] (Jon Isaacs) wrote in message

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Quoted message said:

The two mag trainers I've tried I couldn't reach 400W no matter fast I went (in one case over
90 km/h!).

With the Tacx Cycloforce Swing mag trainer you can reach about 400 W at a cadence of 50 depending on
your gearing of course. Max is maybe 900 W.

I use this trainer mainly because I want to get better at climbing hills.

--
Replace the dots to reply

Perre

(Jon Isaacs) said:

This morning it just so happened that someone (Damon Rinard) had Emailed me about this very issue.
So, before leaving for work, I put my bike with the Powertap on my Mag trainer and would it up to
see how much power I could put out. Unfortunately the tire was slipping but I still managed 1225
watts, not too bad for a maximum effort with no warm up.

Yikes, that's 1.63 horsepower.

Jon, I don't think that I have ever said anything insulting to you, but in the offchance that I
have, please accept my humble apologies.

Ted Bennett