Trainer durability question

David Kerber ns_dkerber@ns_ids.net said:

So my question is: should I expect longer life out of it by running at a higher resistance setting
at a lower wheel speed (and thus lower trainer speed), or a lower resistance at a higher wheel
speed. My initial guess is that a lower speed at the trainer would help it last longer by reducing
the wear on the bearings, but am not sure if the higher temperatures in the load unit (due to
lower cooling air flow) might over-ride the effects of the lower speed in giving me the best
overall life.

I don't know the answer to your question, but I have noticed that at least with my Tacx trainer
noise increases greatly at higher wheel speeds. Because of this, I always use high resistance and
low speed.

-as

"David Kerber" <ns_dkerber@ns_ids.net> wrote in message
"]news:[email hidden]...

Quoted message said:

My wife got me an inexpensive magnetic trainer for Christmas, and I want to get as much use out of
it as possible before it inevitably gives up the ghost in a year or two.

This question assumes I would run a reasonably constant cadence, and adjust the gearing to change
the wheel speed to keep a constant power output.

So my question is: should I expect longer life out of it by running at a higher resistance setting
at a lower wheel speed (and thus lower trainer speed), or a lower resistance at a higher wheel
speed. My initial guess is that a lower speed at the trainer would help it last longer by reducing
the wear on the bearings, but am not sure if the higher temperatures in the load unit (due to
lower cooling air flow) might over-ride the effects of the lower speed in giving me the best
overall life.

If it matters, it's a Graber with a 3-level resistance setting, though I don't know the
exact model.

Given that your power output is the same in both cases, in my opinion there will be no difference.

Phil Holman

David Kerber said:

My wife got me an inexpensive magnetic trainer for Christmas, and I want to get as much use out of
it as possible before it inevitably gives up the ghost in a year or two.

This question assumes I would run a reasonably constant cadence, and adjust the gearing to change
the wheel speed to keep a constant power output.

So my question is: should I expect longer life out of it by running at a higher resistance setting
at a lower wheel speed (and thus lower trainer speed), or a lower resistance at a higher wheel
speed. My initial guess is that a lower speed at the trainer would help it last longer by reducing
the wear on the bearings, but am not sure if the higher temperatures in the load unit (due to
lower cooling air flow) might over-ride the effects of the lower speed in giving me the best
overall life.

If it matters, it's a Graber with a 3-level resistance setting, though I don't know the
exact model.

I don't know.

But I do know the #1 complaint of trainer customers is rapid tire wear caused by insufficient
loading. Set the roller against the tire so it deforms as much as or more than with your weight on
the road. And keep your tire pressure up to the max rating, too. Setting the roller too lightly on
the tire makes a big pile of black tire shavings in no time.

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

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

Quoted message said:

"David Kerber" <ns_dkerber@ns_ids.net> wrote in message
"]news:[email hidden]...

Quoted message said:

My wife got me an inexpensive magnetic trainer for Christmas, and I want to get as much use out
of it as possible before it inevitably gives up the ghost in a year or two.

This question assumes I would run a reasonably constant cadence, and adjust the gearing to
change the wheel speed to keep a constant power output.

So my question is: should I expect longer life out of it by running at a higher resistance
setting at a lower wheel speed (and thus lower trainer speed), or a lower resistance at a higher
wheel speed. My initial guess is that a lower speed at the trainer would help it last longer by
reducing the wear on the bearings, but am not sure if the higher temperatures in the load unit
(due to lower cooling air flow) might over-ride the effects of the lower speed in giving me the
best overall life.

If it matters, it's a Graber with a 3-level resistance setting, though I don't know the exact
model.

Given that your power output is the same in both cases, in my opinion there will be no difference.

Isn't bearing wear largely independent of load?

--
Dave Kerber Fight spam: remove the ns_ from the return address before replying!

REAL programmers write self-modifying code.

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

Quoted message said:

David Kerber said:

My wife got me an inexpensive magnetic trainer for Christmas, and I want to get as much use out
of it as possible before it inevitably gives up the ghost in a year or two.

This question assumes I would run a reasonably constant cadence, and adjust the gearing to
change the wheel speed to keep a constant power output.

So my question is: should I expect longer life out of it by running at a higher resistance
setting at a lower wheel speed (and thus lower trainer speed), or a lower resistance at a higher
wheel speed. My initial guess is that a lower speed at the trainer would help it last longer by
reducing the wear on the bearings, but am not sure if the higher temperatures in the load unit
(due to lower cooling air flow) might over-ride the effects of the lower speed in giving me the
best overall life.

If it matters, it's a Graber with a 3-level resistance setting, though I don't know the exact
model.

I don't know.

But I do know the #1 complaint of trainer customers is rapid tire wear caused by insufficient
loading. Set the roller against the tire so it deforms as much as or more than with your weight on
the road. And keep your tire pressure up to the max rating, too. Setting the roller too lightly on
the tire makes a big pile of black tire shavings in no time.

I didn't realize that; thanks for the suggestion.

--
Dave Kerber Fight spam: remove the ns_ from the return address before replying!

REAL programmers write self-modifying code.

A Muzi said:

But I do know the #1 complaint of trainer customers is rapid tire wear caused by insufficient
loading. Set the roller against the tire so it deforms as much as or more than with your weight on
the road. And keep your tire pressure up to the max rating, too. Setting the roller too lightly on
the tire makes a big pile of black tire shavings in no time.

[OT] but I once set up the trainer on a newish polypropylene rug to try and damp the sound in the
house I had at the time, which had a suspended timber ground floor. Anyway, 40 minutes and a strange
burning smell later, I realised that the trainer had sunk into the pile of the rug sufficiently for
the tyre to make contact. The result was a shiny black stripe of rubber about 4" x 1". Incredibly it
cleaned off with soap and water and the rug was perfect again. Polypropylene is tough stuff.

David Kerber <ns_dkerber@ns_ids.net> wrote in message news:<[email hidden]>...

Quoted message said:

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

Quoted message said:

David Kerber said:

My wife got me an inexpensive magnetic trainer for Christmas, and I want to get as much use
out of it as possible before it inevitably gives up the ghost in a year or two.

This question assumes I would run a reasonably constant cadence, and adjust the gearing to
change the wheel speed to keep a constant power output.

So my question is: should I expect longer life out of it by running at a higher resistance
setting at a lower wheel speed (and thus lower trainer speed), or a lower resistance at a
higher wheel speed. My initial guess is that a lower speed at the trainer would help it last
longer by reducing the wear on the bearings, but am not sure if the higher temperatures in the
load unit (due to lower cooling air flow) might over-ride the effects of the lower speed in
giving me the best overall life.

If it matters, it's a Graber with a 3-level resistance setting, though I don't know the exact
model.

I don't know.

But I do know the #1 complaint of trainer customers is rapid tire wear caused by insufficient
loading. Set the roller against the tire so it deforms as much as or more than with your weight
on the road. And keep your tire pressure up to the max rating, too. Setting the roller too
lightly on the tire makes a big pile of black tire shavings in no time.

I didn't realize that; thanks for the suggestion.

Dear David and Andrew,

Last month, John Forrest Tomlinson suggested roughly the same thing about the dangers of too-light
rear-tire loading on trainers in "Re: trainers tough on wheels?"

John's phrase was "toast," possibly suggesting heat problems, while Andrew uses "shavings."

Do badly adjusted trainers actually leave piles of shavings? Or is the debris more like rubbed-off
grindings or (dare I say it?) crumbs?

I have no trainer beyond the wretched 30-40 mph wind today, so I'm just curious about the details of
these contraptions.

(I ask clean-shaven friends similar questions about electric razors, citing Samuel Marchbanks, who
asked his brother at Christmas if there was no tendency for the skin of the jowls to loosen under
the influence of the electricity and to hang in folds.)

Seriously, what's the actual mode of failure when tires are too lightly loaded in trainers?
Abrasion, peeling, or what?

Carl Fogel

"David Kerber" <ns_dkerber@ns_ids.net> wrote in message
"]news:[email hidden]...

Quoted message said:

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

Quoted message said:

"David Kerber" <ns_dkerber@ns_ids.net> wrote in message
"]news:[email hidden]...

Quoted message said:

My wife got me an inexpensive magnetic trainer for Christmas, and

I

Quoted message said:

Quoted message said:

Quoted message said:

want to get as much use out of it as possible before it inevitably gives up the ghost in a
year or two.

This question assumes I would run a reasonably constant cadence,

and

Quoted message said:

Quoted message said:

Quoted message said:

adjust the gearing to change the wheel speed to keep a constant

power

Quoted message said:

Quoted message said:

Quoted message said:

output.

So my question is: should I expect longer life out of it by

running

Quoted message said:

Quoted message said:

Quoted message said:

at a higher resistance setting at a lower wheel speed (and thus

lower

Quoted message said:

Quoted message said:

Quoted message said:

trainer speed), or a lower resistance at a higher wheel speed. My initial guess is that a
lower speed at the trainer would help it

last

Quoted message said:

Quoted message said:

Quoted message said:

longer by reducing the wear on the bearings, but am not sure if

the

Quoted message said:

Quoted message said:

Quoted message said:

higher temperatures in the load unit (due to lower cooling air flow) might over-ride the
effects of the lower speed in giving me

the

Quoted message said:

Quoted message said:

Quoted message said:

best overall life.

If it matters, it's a Graber with a 3-level resistance setting, though I don't know the exact
model.

Given that your power output is the same in both cases, in my

opinion

Quoted message said:

Quoted message said:

there will be no difference.

Isn't bearing wear largely independent of load?

Did you mean dependent?

In your case, the increase in load is offset by fewer revolutions. I put serious miles on my trainer
and have yet to see any sign of wear in the bearings.

Phil Holman

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

Quoted message said:

Do badly adjusted trainers actually leave piles of shavings? Or is the debris more like rubbed-off
grindings or (dare I say it?) crumbs?

Seriously, what's the actual mode of failure when tires are too lightly loaded in trainers?
Abrasion, peeling, or what?

I would guess it's abrasion. All I know is I end up with this lovely band of melted rubber around
the middle of my trainer's roller every so often. I suspect it's just premature wear, the normal
wear mode being abrasion I would imagine. I often wonder how much rubber dust goes into the air
along your average interstate...those tires have to go somewhere!! ;-)

Cheers,

Scott..

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

Quoted message said:

David Kerber <ns_dkerber@ns_ids.net> wrote in message

news:<[email hidden]>...

Quoted message said:

Quoted message said:

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

Quoted message said:

David Kerber wrote:

> My wife got me an inexpensive magnetic trainer for Christmas,

and I

Quoted message said:

Quoted message said:

Quoted message said:

> want to get as much use out of it as possible before it

inevitably

Quoted message said:

Quoted message said:

Quoted message said:

> gives up the ghost in a year or two.
>
> This question assumes I would run a reasonably constant cadence,

and

Quoted message said:

Quoted message said:

Quoted message said:

> adjust the gearing to change the wheel speed to keep a constant

power

Quoted message said:

Quoted message said:

Quoted message said:

> output.
>
> So my question is: should I expect longer life out of it by

running

Quoted message said:

Quoted message said:

Quoted message said:

> at a higher resistance setting at a lower wheel speed (and thus

lower

Quoted message said:

Quoted message said:

Quoted message said:

> trainer speed), or a lower resistance at a higher wheel speed.

My

Quoted message said:

Quoted message said:

Quoted message said:

> initial guess is that a lower speed at the trainer would help it

last

Quoted message said:

Quoted message said:

Quoted message said:

> longer by reducing the wear on the bearings, but am not sure if

the

Quoted message said:

Quoted message said:

Quoted message said:

> higher temperatures in the load unit (due to lower cooling air flow) might over-ride the
> effects of the lower speed in giving

me the

Quoted message said:

Quoted message said:

Quoted message said:

> best overall life.
>
> If it matters, it's a Graber with a 3-level resistance setting, though I don't know the
> exact model.
>
I don't know.

But I do know the #1 complaint of trainer customers is rapid tire wear caused by insufficient
loading. Set the roller against the tire so it deforms as much as or more than with your
weight on the road. And keep your tire pressure up to the max rating, too. Setting the roller
too lightly on the tire makes a big pile of black tire shavings in no time.

I didn't realize that; thanks for the suggestion.

Dear David and Andrew,

Last month, John Forrest Tomlinson suggested roughly the same thing about the dangers of too-light
rear-tire loading on trainers in "Re: trainers tough on wheels?"

John's phrase was "toast," possibly suggesting heat problems, while Andrew uses "shavings."

Do badly adjusted trainers actually leave piles of shavings? Or is the debris more like rubbed-off
grindings or (dare I say it?) crumbs?

I have no trainer beyond the wretched 30-40 mph wind today, so I'm just curious about the details
of these contraptions.

(I ask clean-shaven friends similar questions about electric razors, citing Samuel Marchbanks, who
asked his brother at Christmas if there was no tendency for the skin of the jowls to loosen under
the influence of the electricity and to hang in folds.)

Seriously, what's the actual mode of failure when tires are too lightly loaded in trainers?
Abrasion, peeling, or what?

The tire slips on the roller causing overheating which deteriorates the rubber and will rapidly
trash the tire. Here is my tip. Always inflate the tire to rated pressure. Insure pressure against
the roller is just high enough by making sure you cannot cause it to slip by holding the roller
still and trying to rotate the wheel by hand. Make sure it is not too tight against the roller
either or the increased tire deflection will also wear the tire prematurely. I only use tires that
are worn out from road use and they last a very long time on the trainer.

Phil Holman

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

Quoted message said:

"David Kerber" <ns_dkerber@ns_ids.net> wrote in message
"]news:[email hidden]...

Quoted message said:

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

Quoted message said:

"David Kerber" <ns_dkerber@ns_ids.net> wrote in message
"]news:[email hidden]...
> My wife got me an inexpensive magnetic trainer for Christmas, and

I

Quoted message said:

Quoted message said:

> want to get as much use out of it as possible before it inevitably gives up the ghost in a
> year or two.
>
> This question assumes I would run a reasonably constant cadence,

and

Quoted message said:

Quoted message said:

> adjust the gearing to change the wheel speed to keep a constant

power

Quoted message said:

Quoted message said:

> output.
>
> So my question is: should I expect longer life out of it by

running

Quoted message said:

Quoted message said:

> at a higher resistance setting at a lower wheel speed (and thus

lower

Quoted message said:

Quoted message said:

> trainer speed), or a lower resistance at a higher wheel speed. My initial guess is that a
> lower speed at the trainer would help it

last

Quoted message said:

Quoted message said:

> longer by reducing the wear on the bearings, but am not sure if

the

Quoted message said:

Quoted message said:

> higher temperatures in the load unit (due to lower cooling air flow) might over-ride the
> effects of the lower speed in giving me

the

Quoted message said:

Quoted message said:

> best overall life.
>
> If it matters, it's a Graber with a 3-level resistance setting, though I don't know the
> exact model.

Given that your power output is the same in both cases, in my

opinion

Quoted message said:

Quoted message said:

there will be no difference.

Isn't bearing wear largely independent of load?

Did you mean dependent?

No, I meant what I said. Why would bearing wear be dependent on the load (power being transmitted)
through the axle of the mag unit? I realize wear would be dependent on the radial load, but that
will be constant, and is adjusted by the setting the adjustment screw to press it against the wheel.
The torque loading, as adjusted by the magnetic setting, wouldn't seem to me to affect the bearings
hardly at all.

Quoted message said:

In your case, the increase in load is offset by fewer revolutions. I put serious miles on my
trainer and have yet to see any sign of wear in the bearings.

Do you run higher resistance settings with lower wheel speeds, or vice- versa?

--
Dave Kerber Fight spam: remove the ns_ from the return address before replying!

REAL programmers write self-modifying code.

"David Kerber" <ns_dkerber@ns_ids.net> wrote in message >

Quoted message said:

Do you run higher resistance settings with lower wheel speeds, or vice- versa?

--
Dave Kerber

FWIW, I have a Minoura Mag trainer (about $189CDN, cheap I would say..) and I've used it for 2
winters, about 5 hours a week for 8 months in total. It's still going pretty well. I use higher
resistance settings and I use only the small ring in the front, except when I do some "climbing"
simulations for 5 minute intervals every now and again. During this time my cadence drops to 60-
70rpm so that probably means the same speed on the roller overall.

Cheers,

Scott..

"David Kerber" <ns_dkerber@ns_ids.net> wrote in message >

Quoted message said:

Do you run higher resistance settings with lower wheel speeds, or vice- versa?

--
Dave Kerber

FWIW, I have a Minoura Mag trainer (about $189CDN, cheap I would say..) and I've used it for 2
winters, about 5 hours a week for 8 months in total. It's still going pretty well. I use higher
resistance settings and I use only the small ring in the front, except when I do some "climbing"
simulations for 5 minute intervals every now and again. During this time my cadence drops to 60-
70rpm so that probably means the same speed on the roller overall.

Cheers,

Scott..

David Kerber <ns_dkerber@ns_ids.net> wrote in message news:<[email hidden]>...

Quoted message said:

No, I meant what I said. Why would bearing wear be dependent on the load (power being
transmitted) through the axle of the mag unit? I realize wear would be dependent on the radial
load, but that will be constant, and is adjusted by the setting the adjustment screw to press it
against the wheel.

On a trainer set up to work without slip in all combinations of gear, resistance and power your
point would be valid.

But on a trainer set up to use one end of the trainer-resistance range (which is what we are talking
about) there shouldn't be much difference since you need more load on the roller to prevent slip if
you are using the high resistance settings. (This assumes more tyre pressure to maintain tyre
deformation resistance)

I doubt if I'll ever wear out my trainer (does anybody derive any kind of pleasure from using
these?) but in theory a trainer used in many combinations is likely to wear faster.

Andrew Bradley

"David Kerber" <ns_dkerber@ns_ids.net> wrote in message
"]news:[email hidden]...

Quoted message said:

My wife got me an inexpensive magnetic trainer for Christmas, and I want to get as much use out of
it as possible before it inevitably gives up the ghost in a year or two.

I have had a Blackburn mag trainer for a few years. I have had occasion to disassemble it. What I
found was that it is very simple, with just an aluminum disc rotating between 2 stationary plates
that have ceramic magnets glued to them. The resistance adjustment simply changes the spacing
between the sets of magnets. What I found, when mine started making noise, was that the set screw
had slipped, and the rotating disc was contacting the magnets. It probably would have failed soon. I
had heard reports of several of these failing in that way.

The bearings on mine are very beefy looking cartridge bearings, they look like they'll last forever.
I know my old wind trainer lasted for many years before I got tired of its howling and trashed it.
It was still working well when I threw it out. A mag trainer should be similarly long-lived.

"David Kerber" <ns_dkerber@ns_ids.net> wrote in message
"]news:[email hidden]...

Quoted message said:

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

Quoted message said:

"David Kerber" <ns_dkerber@ns_ids.net> wrote in message
"]news:[email hidden]...

Quoted message said:

In article <[email hidden]>, [email hidden]
says...
>
> "David Kerber" <ns_dkerber@ns_ids.net> wrote in message
> "]news:[email hidden]...
> > My wife got me an inexpensive magnetic trainer for Christmas,

and

Quoted message said:

Quoted message said:

I

Quoted message said:

> > want to get as much use out of it as possible before it

inevitably

Quoted message said:

Quoted message said:

Quoted message said:

> > gives up the ghost in a year or two.
> >
> > This question assumes I would run a reasonably constant

cadence,

Quoted message said:

Quoted message said:

and

Quoted message said:

> > adjust the gearing to change the wheel speed to keep a

constant

Quoted message said:

Quoted message said:

power

Quoted message said:

> > output.
> >
> > So my question is: should I expect longer life out of it by

running

Quoted message said:

> > at a higher resistance setting at a lower wheel speed (and

thus

Quoted message said:

Quoted message said:

lower

Quoted message said:

> > trainer speed), or a lower resistance at a higher wheel speed.

My

Quoted message said:

Quoted message said:

Quoted message said:

> > initial guess is that a lower speed at the trainer would help

it

Quoted message said:

Quoted message said:

last

Quoted message said:

> > longer by reducing the wear on the bearings, but am not sure

if

Quoted message said:

Quoted message said:

the

Quoted message said:

> > higher temperatures in the load unit (due to lower cooling air flow) might over-ride the
> > effects of the lower speed in giving

me

Quoted message said:

Quoted message said:

the

Quoted message said:

> > best overall life.
> >
> > If it matters, it's a Graber with a 3-level resistance

setting,

Quoted message said:

Quoted message said:

Quoted message said:

> > though I don't know the exact model.
>
> Given that your power output is the same in both cases, in my

opinion

Quoted message said:

> there will be no difference.

Isn't bearing wear largely independent of load?

Did you mean dependent?

No, I meant what I said. Why would bearing wear be dependent on the load (power being transmitted)
through the axle of the mag unit? I realize wear would be dependent on the radial load, but that
will be constant, and is adjusted by the setting the adjustment screw to press it against the
wheel. The torque loading, as adjusted by the magnetic setting, wouldn't seem to me to affect the
bearings hardly at all.

Well, lets run some numbers and see. If we look at a nominal rider output of 220 ft.lb/sec
(approx.300watts) with a 40 lb tire pressure onto the roller, under a hillclimb situation at 7 mph,
the combination of radial and tangential load is Sqrt (40^2 + 20^2) = 45 lb. This is a load of 45 lb
at the center of the roller plus a 4 lb load (20 lb load factored down by the ratio of roller radius
to magnetic resistance radius) at the end of the roller reacting the magnetic resistance. The
bearings will react two forces 45 lb and 4 lb. If we look at the same power output but a lower
resistance where we spin at 28 mph, the two forces reduce to 40.3 lb and 1 lb respectively. It
depends on the relative direction of these 2 forces to determine which bearing receives the highest
load. We could assume a 15% higher load at 1/4 speed for the hillclimbing scenario.

Quoted message said:

Quoted message said:

In your case, the increase in load is offset by fewer revolutions. I

put

Quoted message said:

Quoted message said:

serious miles on my trainer and have yet to see any sign of wear in

the

Quoted message said:

Quoted message said:

bearings.

Do you run higher resistance settings with lower wheel speeds, or

vice-

Quoted message said:

versa?

I tend to simulate actual road/track conditions. 300 watts at 25mph for endurance and 450-500watts
intervals at 30-32 mph. I don't do any hillclimb simulations because I think these are too hard on
the bike frame. I really don't see you wearing these bearings out in a year or even 10 years.

Phil Holman

In article <QqkHb.151486$8y1.444152@attbi_s52>, [email hidden] says...

Quoted message said:

"David Kerber" <ns_dkerber@ns_ids.net> wrote in message
"]news:[email hidden]...

Quoted message said:

My wife got me an inexpensive magnetic trainer for Christmas, and I want to get as much use out
of it as possible before it inevitably gives up the ghost in a year or two.

I have had a Blackburn mag trainer for a few years. I have had occasion to disassemble it. What I
found was that it is very simple, with just an aluminum disc rotating between 2 stationary plates
that have ceramic magnets glued to them. The resistance adjustment simply changes the spacing
between the sets of magnets. What I found, when mine started making noise, was that the set screw
had slipped, and the rotating disc was contacting the magnets. It probably would have failed soon.
I had heard reports of several of these failing in that way.

The bearings on mine are very beefy looking cartridge bearings, they look like they'll last
forever. I know my old wind trainer lasted for many years before I got tired of its howling and
trashed it. It was still working well when I threw it out. A mag trainer should be similarly
long-lived.

That's the kind of info I was working for; thanks!

--
Dave Kerber Fight spam: remove the ns_ from the return address before replying!

REAL programmers write self-modifying code.