Mag or fluid trainers?

[Zilla]

What are the pros and cons of one versus the other? I want to use one for indoor riding when it's
too damn cold outside (for me). Also would you recommend one with "automatic variable" resistance
(fluids have these) or a manually adjustable resistance?

--
- Zilla Cary, NC (Remove XSPAM)

 

[Qui Si Parla Ca]

zilla-<< What are the pros and cons of one versus the other? I want to use one for indoor riding
when it's too damn cold outside (for me). >><BR><BR>

I would say a good set of rollers. Not hard to use, time passes more quickly since ya gotta
concentrate. makes your pedaling style very smooth, very 'round' and teaches you to ride straight.
Decent rollers are in the same price range as other trainers.

Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St. Boulder, CO, 80302
(303)440-3535 http://www.vecchios.com "Ruote convenzionali costruite eccezionalmente bene"

 

[W.A. Manning]

get a fluid. i've owned them all, and fluid rocks. realistic ramp-up of resistance. quiet. there is
the risk of fluid leakage, but that has been minimized in current designs. in fact, the design by
kurt is completely sealed.

 

[Peter Guidry]

[email protected] (w.a. manning) wrote in message news:<[email protected]>...
> get a fluid. i've owned them all, and fluid rocks. realistic ramp-up of resistance. quiet. there
> is the risk of fluid leakage, but that has been minimized in current designs. in fact, the design
> by kurt is completely sealed.

From what I read this is correct. But I have a mag unit because I think the Kurt is the only fluid
to get and they wan't $500 CDN for when I talk to a local shop. Since Kurt has only sealed fluid
design it is the only one to consider. Here are some differences:

Magnetic and fluid are both quiet. The main noise I get with magnetic is the drivetrain noise of the
bike. Magnetic resistance is linear (unlike real world). Fluid is exponential like real world. Kurt
fluid is tuned to equal real world. Kurt comes with bigger flywheels for smoother road feel.

Personally I wanted the Kurt Fluid, but at about 4 times the price of the mag unit, I decided I
could live the less realistic power and feel of a mag unit.

Peter

 

[Cipher]

If you want to consider a cheap alternative, try Ebay, I picked up a brand new Blackburn MagTrackstand XR-6 mag trainer for $50.00, and it works great.

 

[Robert Chung]

Peter Guidry wrote:
> Magnetic resistance is linear (unlike real world). Fluid is exponential like real world. Kurt
> fluid is tuned to equal real world. Kurt comes with bigger flywheels for smoother road feel.

Over the years I've had a wind trainer, rollers, and a mag trainer. None of them have had anything
like real world road feel and I've come to the thought that real world road feel is not that
critical from a training perspective. Electrically-braked ergometers set for a fixed wattage don't
have real world road feel yet they're fine for indoor training. If I had to do it over I'd make my
purchasing decision on noise level, price, sturdiness, and foldability -- road feel or the lack of
it would come way down the list.

 

[A Muzi]

> [email protected] (w.a. manning) wrote in message news:<[email protected]>...
>>get a fluid. i've owned them all, and fluid rocks. realistic ramp-up of resistance. quiet. there
>>is the risk of fluid leakage, but that has been minimized in current designs. in fact, the design
>>by kurt is completely sealed.

Peter Guidry wrote: -snip- Since Kurt has only sealed fluid design
> it is the only one to consider.
-snip-:

I've been in the CycleOps factory where each unit is spun, with a PowerTap setup, in a black light
booth to spot leaks of the fluorescent fluid. There are virtually none. I sell a very large number
of them and have seen exactly zero leaks since the original CycleOps folded and Graber bought the
company four years ago. Do you know of a leaking Graber-built CycleOps?

$216 versus $500 is a significant difference, IMHO.

--
Andrew Muzi www.yellowjersey.org Open every day since 1 April, 1971

 

[jlscott3]

Originally posted by Zilla

> What are the pros and cons of one versus the other?
> I want to use one for indoor riding when it's
> too damn cold outside (for me). Also would you recommend
> one with "automatic variable" resistance
> (fluids have these) or a manually adjustable resistance?

I've ridden a Cycleops fluid trainer a couple of hours a week since November. That's the sum total of my trainer experience, so keep that in mind as you read.

1. I chose fluid over mag due to the geometric resistance curve of fluid. I like the simplicity - just hop on and go. No need to worry about setting the resistance level, just upshift/pedal faster.

2. In terms of training goals, don't expect that you'll be able to tune your trainer to the point where you can compare your results to what you get on the road. IMHO, it's either impossible or too much trouble. So far I haven't installed a cyclocomputer for the trainer, I'm just using my HRM and counting cadence in my head.

I'll second what Robert Chung wrote - the environmental concerns for trainer workouts are more of a consideration than the type of resistance you use. How will you stay focused? How will you manage the dripping sweat? How much noise can you tolerate, and how much space do you have? For a beginning trainer rider, those questions are much more important than fluid vs. mag.

JLS

 

[Owen Pope]

A Muzi <[email protected]> wrote in
news:[email protected]:

>> [email protected] (w.a. manning) wrote in message
>> news:<[email protected]>...
>>>get a fluid. i've owned them all, and fluid rocks. realistic ramp-up of resistance. quiet. there
>>>is the risk of fluid leakage, but that has been minimized in current designs. in fact, the design
>>>by kurt is completely sealed.
>
> Peter Guidry wrote: -snip- Since Kurt has only sealed fluid design
>> it is the only one to consider.
> -snip-:
>
> I've been in the CycleOps factory where each unit is spun, with a PowerTap setup, in a black light
> booth to spot leaks of the fluorescent fluid. There are virtually none. I sell a very large number
> of them and have seen exactly zero leaks since the original CycleOps folded and Graber bought the
> company four years ago. Do you know of a leaking Graber-built CycleOps?
>
> $216 versus $500 is a significant difference, IMHO.

You must be the only person selling them for less than $270, then. Remember that the $500 mentioned
above is in Canadian, they're about $300 US. Which is about $15 more than the usual Cycle-ops price.

-Owen

 

[Zilla]

jlscott3 wrote:
> Originally posted by Zilla
>
>> What are the pros and cons of one versus the other? I want to use one for indoor riding when it's
>> too damn cold outside (for me). Also would you recommend one with "automatic variable" resistance
>> (fluids have these) or a manually adjustable resistance?
>
> I've ridden a Cycleops fluid trainer a couple of hours a week since November. That's the sum total
> of my trainer experience, so keep that in mind as you read.
>
> 1. I chose fluid over mag due to the geometric resistance curve of fluid. I like the simplicity -
> just hop on and go. No need to worry about setting the resistance level, just upshift/pedal
> faster.
>
> 2. In terms of training goals, don't expect that you'll be able to tune your trainer to the point
> where you can compare your results to what you get on the road. IMHO, it's either impossible or
> too much trouble. So far I haven't installed a cyclocomputer for the trainer, I'm just using my
> HRM and counting cadence in my head.
>
> I'll second what Robert Chung wrote - the environmental concerns for trainer workouts are more of
> a consideration than the type of resistance you use. How will you stay focused? How will you
> manage the dripping sweat? How much noise can you tolerate, and how much space do you have? For a
> beginning trainer rider, those questions are much more important than fluid vs. mag.
>
> JLS

I asked for pros and cons for each. I prefer the lower noise so which model provides this? As far as
the other considerations - concentration, sweat, etc. - I'll handle, but they don't cost money.

--
- Zilla Cary, NC (Remove XSPAM)

 

[N2vx Jim]

On Tue, 27 Jan 2004 04:32:04 +0100, "Robert Chung"
<[email protected]> wrote:

>Peter Guidry wrote:
>> Magnetic resistance is linear (unlike real world). Fluid is exponential like real world. Kurt
>> fluid is tuned to equal real world. Kurt comes with bigger flywheels for smoother road feel.
>
>Over the years I've had a wind trainer, rollers, and a mag trainer. None of them have had anything
>like real world road feel and I've come to the thought that real world road feel is not that
>critical from a training perspective. Electrically-braked ergometers set for a fixed wattage don't
>have real world road feel yet they're fine for indoor training. If I had to do it over I'd make my
>purchasing decision on noise level, price, sturdiness, and foldability -- road feel or the lack of
>it would come way down the list.

How about one that drives a generator? I stuck a permanent magnet DC motor (110 volt treadmill
motor) on an old Schwin trainer and use it to run a 150 watt light bulb. Light brightness gives
a good indication of your power output. I thought about using a voltmeter but it wasn't worth
the effort.

It doesn't feel like the road and I'll go with Robert on that part of it: it doesn't really matter.

If you're a stud monkey use two or three 150 watt bulbs.

Jim

 

[Peter Guidry]

"Zilla" <[email protected]> wrote in message news:<[email protected]>...

> I asked for pros and cons for each. I prefer the lower noise so which model provides this? As far
> as the other considerations - concentration, sweat, etc. - I'll handle, but they don't cost money.

I have read that fluid is quieter, but that is usually in fluid trainer adverts. I hear nothing from
my mag unit. I get squeaks from the tire until the tire warms up (it is not loose BTW). After that
it is mostly bicycle drivetrain and whiring spokes.

My take: Cost no object I would get a Kurt Kinetic fluid trainer. Cost was an object for me. I
bought a mag trainer.

I dissagree with those who call the road feel irrelevant. With very small flywheel on my mag unit.
It spins down near instantly if I back off pedalling, making it feel more like grind than biking on
the road. A bit of coast would be apreciated and make it a more pleasant experience. Riding indoors
is enough of a drag without making it any worse.

I also like the fact that the Kurt has been finely calibrated to at least attempt to equal power
burned on the road at various speeds.

 

[Peter Guidry]

A Muzi <[email protected]> wrote in message news:<[email protected]>...

>
> I've been in the CycleOps factory where each unit is spun, with a PowerTap setup, in a black light
> booth to spot leaks of the fluorescent fluid. There are virtually none. I sell a very large number
> of them and have seen exactly zero leaks since the original CycleOps folded and Graber bought the
> company four years ago. Do you know of a leaking Graber-built CycleOps?
>
> $216 versus $500 is a significant difference, IMHO.

My local dealer in Canada also wanted $500 for the CycleOps fluid 2.

http://www.roadbikereview.com/Trainers/CycleOps,Fluid,2/PRD_49219_1663crx.aspx

I believe this unit is built since Graber took over. Quite a few of the reviews report leaks.
They still have a shaft into the fluid chamber and still have o-ring seal to stop leaks. Seals
can wear out.

The Kurt unit is sealed, no shaft. The fluid resistance unit is driven by magnets so the chamber can
be completely sealed.

I have no affiliation with Kurt and I think both units are too damn expensive, but if I were
spending that kind of money, I would get the completely sealed unit. Kurt also has a 6 pound
flywheel option to improve that roadfeel which no one here cares about apparently.

 

[Robert Chung]

Peter Guidry wrote:
>
> I dissagree with those who call the road feel irrelevant. With very small flywheel on my mag unit.
> It spins down near instantly if I back off pedalling, making it feel more like grind than biking
> on the road.

Read this to see why a 6-lb flywheel is insufficient: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi-
?cmd=Retrieve&db=PubMed&list_uids=11036570&dopt=Abstract
http://aemes.mae.ufl.edu/~fregly/pdfs/jbme2000.pdf

If you're really convinced that inertial load matters that much, then you should sneer at a girly
6-lb flywheel. Real Men would willingly shell out $5500US for the Velotron (http://www.velotron.com)
with its manly 55-lb flywheel.

> I also like the fact that the Kurt has been finely calibrated to at least attempt to equal power
> burned on the road at various speeds.

Why would you think this is important? In the real world the power-speed relationship isn't
constant; rather, it varies with terrain and wind.

Don't take this as a criticism of the Kurt Kinetic. I simply think that noise level, price,
stability, foldability, and quality of construction are more important. The Kurt rates high on all
of these except for price. Don't feel disappointed because you have a mag trainer. The grass isn't
always greener on the other side of the fence.

 

[Peter Guidry]

"Robert Chung" <[email protected]> wrote in message news:

> Read this to see why a 6-lb flywheel is insufficient: http://www.ncbi.nlm.nih.gov/entrez/query.fc-
> gi?cmd=Retrieve&db=PubMed&list_uids=11036570&dopt=Abstract
> http://aemes.mae.ufl.edu/~fregly/pdfs/jbme2000.pdf
>
> If you're really convinced that inertial load matters that much, then you should sneer at a girly
> 6-lb flywheel. Real Men would willingly shell out $5500US for the Velotron
> (http://www.velotron.com) with its manly 55-lb flywheel.

Did I claim perfect? I just want better. I understand the difficulty of perfect emulation, but I
don't see the reasoning in: "I can't have perfect, so I should choose worse".

>
> > I also like the fact that the Kurt has been finely calibrated to at least attempt to equal power
> > burned on the road at various speeds.
>
> Why would you think this is important? In the real world the power-speed relationship isn't
> constant; rather, it varies with terrain and wind.

Again this seems like an argument saying it can't be perfect, so choose worse.

Lets see given a choice between:

A: a unit that is calibrated to emulate a rider on flat road with no wind and with resistance that
keeps that calibration as speed increases because it has an exponential increase.

B: a unit that is not calibrated to anything, and even if it was it would only be at one speed as
the resistance doesn't increse exponentially.

Would you chose B? because A is not perfectly realistic? I certainly wouldn't. I would choose since
is closer to realistic.

> Don't take this as a criticism of the Kurt Kinetic. I simply think that noise level, price,
> stability, foldability, and quality of construction are more important. The Kurt rates high on all
> of these except for price. Don't feel disappointed because you have a mag trainer. The grass isn't
> always greener on the other side of the fence.

I said if I were going to spend $300 US on a trainer I would get the Kurt, but price being an issue
for me, I went magnetic.

Bottom line: I would like more inertia than the 1 pound (under?) on my mag trainer. Simply for it to
be a more pleasant experience. With instant coast down, a low inertia trainer feels like you are
always riding uphill, where you can't let up or you stop. I would prefer it felt a bit more like
riding on the flats. YMMV

Peter

 

[Robert Chung]

Peter Guidry wrote:
> Again this seems like an argument saying it can't be perfect, so choose worse.

Then you have mischaracterized my argument. My argument is that for training purposes, road feel is
not of critical importance. That is not to say there is no difference whatsoever. See: http://www.n-
cbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11784546&dopt=Abstract

> Lets see given a choice between:
>
> A: a unit that is calibrated to emulate a rider on flat road with no wind and with resistance
> that keeps that calibration as speed increases because it has an exponential increase.
>
> B: a unit that is not calibrated to anything, and even if it was it would only be at one speed as
> the resistance doesn't increse exponentially.
>
> Would you chose B? because A is not perfectly realistic? I certainly wouldn't. I would choose
> since is closer to realistic.

No trainer is "not calibrated to anything." And no trainer that I've seen increases resistance
"exponentially" -- even on theoretical grounds one might not want it to scale faster than with a
cubic. Having said that, even the Kurt Kinetic doesn't appear to be calibrated the way that you
think, nor do most other trainers appear that horrendously mis-calibrated as you fear, whether fan,
fluid, or magnetic: http://www.geocities.com/almost_fast/trainerpower/

I wrote "most" in the paragraph above because a couple of those other trainers do appear way odder
than the others -- not that that's necessarily bad. I have a trainer that doubles as a load-
generated ergometer. The raison d'etre for any ergometer is to decouple the fixed link between
speed and power. I'm not nearly so sure as you appear to be that this is an unambiguously inferior
thing to do.

 

[Robert Chung]

I wrote:
> I have a trainer that doubles as a load-generated ergometer. The raison d'etre for any ergometer
> is to decouple the fixed link between speed and power.

Sorry. I meant "the raison d'etre for any load-generated ergometer."

 

[Tom Compton]

"Robert Chung" <[email protected]> wrote in message
news:[email protected]...
> Peter Guidry wrote:
> >
> > I dissagree with those who call the road feel irrelevant. With very small flywheel on my mag
> > unit. It spins down near instantly if I back off pedalling, making it feel more like grind than
> > biking on the road.
>
> Read this to see why a 6-lb flywheel is insufficient:
>
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_ui
ds=11036570&dopt=Abstract
> http://aemes.mae.ufl.edu/~fregly/pdfs/jbme2000.pdf
>
> If you're really convinced that inertial load matters that much, then you should sneer at a girly
> 6-lb flywheel. Real Men would willingly shell out $5500US for the Velotron
> (http://www.velotron.com) with its manly 55-lb flywheel.

In the study cited above, the authors matched the inertia of rider on a flat road with the inertia
of a flywheel. There are small accelerations within a pedal stroke. And it's the mass and the forces
acting on that mass that determine the acceleration of the rider and the acceleration within a pedal
stroke. The mass has to accelerate while the forces of wind, slope, and rolling resistance act on
it. And in the case of wind, the wind force changes with the square of the change in speed
(acceleration). These forces acting on the mass change the pedal response and make the response
different from pedaling against a simple inertia. It's this difference in acceleration that accounts
for the difference in feel between trainers and the road. A calculator that shows these
interactions: http://www.analyticcycling.com/PedalAcc_Page.html

While not heavy in the above context, what is described as a heavy flywheel on a trainer does give a
much better feel to the device. A heavier flywheel "takes the edge off" the too-fast pedal
acceleration. Is it a perfect? No. Is it much better? Oh, yes.

>
> > I also like the fact that the Kurt has been finely calibrated to at least attempt to equal power
> > burned on the road at various speeds.
>
> Why would you think this is important? In the real world the power-speed relationship isn't
> constant; rather, it varies with terrain and wind.
>
One advantage of having a known power-verses-speed curve is that one can convert a speed reading on
a cyclocomputer to power, handy for those that don't have a power meter.

Regards,

Tom Compton www.AnalyticCycling.com

 

[Robert Chung]

Tom Compton wrote:
> While not heavy in the above context, what is described as a heavy flywheel on a trainer does give
> a much better feel to the device. A heavier flywheel "takes the edge off" the too-fast pedal
> acceleration. Is it a perfect? No. Is it much better? Oh, yes.

Tom, I'd agree, as I think I said above, that a flywheel does change the feel. What I said is that
the 6-lb flywheel on a Kurt Kinetic doesn't make a critical difference in training. My Tacx Flow
doesn't have realistic road feel and I'm not sure it makes much of a training difference.

>>> I also like the fact that the Kurt has been finely calibrated to at least attempt to equal power
>>> burned on the road at various speeds.
>>
>> Why would you think this is important? In the real world the power-speed relationship isn't
>> constant; rather, it varies with terrain and wind.
>>
> One advantage of having a known power-verses-speed curve is that one can convert a speed reading
> on a cyclocomputer to power, handy for those that don't have a power meter.

Yes, exactly, and that's why that page that AlmostFast put up is so handy, regardless of how
realistic the curves are, such as the bizarrely unrealistic CycleOps Magneto. BTW, I know you
supplied some of the data for that page, including the Kurt Kinetic models: how did you standardize
the tire-roller interface when you collected your measurements? And did you ever figure out why you
got different curves on different trials?

--Robert

 

[Peter Guidry]

"Robert Chung" <[email protected]> wrote in message news:
> No trainer is "not calibrated to anything." And no trainer that I've seen increases resistance
> "exponentially" -- even on theoretical grounds one might not want it to scale faster than with a
> cubic. Having said that, even the Kurt Kinetic doesn't appear to be calibrated the way that you
> think, nor do most other trainers appear that horrendously mis-calibrated as you fear, whether
> fan, fluid, or magnetic: http://www.geocities.com/almost_fast/trainerpower/

Thanks for the link. I would much rather have the curve that closer approximates reality. I have a
Nashbar/Minoura unit. And while I can cruise easily at 25KM/h in the real world ( 100 watts by the
validated model). At the same speed the Mag unit requires 300 Watts !! How much more wrong could you
expect?? That is 200% error.

I am no racer (obviously) and I have no argument about training affect. As long as you have
resistance and work against you will get training affect. If I left the impression that I thought
there would be a training difference, that was not my intent.

I am just a couch potatoe that wants a trainer that is more "fun" to use, longer spin down and
more realistic resistance curve would make it more fun for me. Right now it feels like riding up
hill. I cruise at the speed that I normally climb hills at and if I stop pedalling for a second,
the bike stops.

So I agree there may be minimal training (or no) difference from [un]relistic nature of the
resistance curve. For me at least there is differnce in how much I will want to ride the damn
thing. YMMV.

Peter