treadmill, how accurate is mph and BPM?

In article said:

The speed in mph of a treadmill........how can I tell how
accurate it is? Is there a general rule like "usually
accurate within plus/minus X percent"........?

Very accurate, probably 1% or so. At least accurate enough
that for the most part, other factors (the fairly forgiving
surface, heat accumultion issues, etc) seem to play a
greater role than miscalibrations.

The heart rate monitors are good, but it's tricky to use
them while youre running.

Cheers,
--
Donovan Rebbechi pegasus.rutgers.edu~elflordOpen ↗

"Lee Carkenord" <[email hidden]> wrote in message

Quoted message said:

The speed in mph of a treadmill........how can I tell how
accurate it is? Is there a general rule like "usually
accurate within plus/minus X percent"........?

You will need to measure the length of the belt and do some
math to find out how accurate the treadmill is.

Quoted message said:

Same with the heart rate that some of the treadmills
display........how accurate might that readout be?

1. The treadmill picks up the signal from your existing HRM
and simply displays it, or
2. You grip a bar in front or beside you (annoying,
obviously, but a reasonable method on a stationary
recumbant bike).

Both methods are accurate, provided the contact points are
wet.

cheers,
--
David (in Hamilton, ON) www.allfalldown.org "The most
insecure people are the ones you see, putting other people
down constantly."

Lee Carkenord said:

The speed in mph of a treadmill........how can I tell how
accurate it is? Is there a general rule like "usually
accurate within plus/minus X percent"........?

Google for "It's Treadmill time again". Look for Lorne
Sundby's post of Dec 14, 2001, for directions on calibrating
treadmill and observations on errors. If you google for some
of Lorne's other posts on treadmills I think you'll find he
reports errors of about 5-10% on the speed and a base
incline that was 3%, not flat. Lorne is also a stickler
about details.

When doing 24-hr tm events for world records, I think they
are required to recalibrate every hour or so - but that's to
maintain quality suitable for records and might be accuracy
beyond what you need.

Quoted message said:

Same with the heart rate that some of the treadmills
display........how accurate might that readout be?

don't know. I use my own hrm.

Dot

--
"Success is different things to different people" -Bernd
Heinrich in Racing the Antelope

Quoted message said:

Google for "It's Treadmill time again".

<snip> I second that. On our treadmills at the gym there is
a drift away from a Breitling of quite a few seconds per km;
so much that trying to train reps will give you false
readings by 2 or 3 seconds per 400 metres. And that's if the
metre measurement is accurate ... The hrms are probvably as
accurate as any hrms, though. J

This is a running newsgroup, not about machines that make a
poor substitute for it.

"rick++" <[email hidden]> wrote in message

Quoted message said:

This is a running newsgroup, not about machines that make
a poor substitute for it.

psssh.

I run a lot on treadmills. I'm generally top 1% - 3% in
about every race I enter. I used to run a lot more on the
road but I had various injury problems. The treadmill allows
me to keep running week after week without interruption,
which IMO is a key factor in getting better.

My friend is one of the best 50+ runners in Canada and does
nothing but stationary recumbant bike training.

Certainly different things work for different people - you
can't just dismiss a training method because it doesn't
work for you.

cheers,
--
David (in Hamilton, ON) www.allfalldown.org "The most
insecure people are the ones you see, putting other people
down constantly."

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

The speed in mph of a treadmill........how can I tell how
accurate it is? Is there a general rule like "usually
accurate within plus/minus X percent"........?

Same with the heart rate that some of the treadmills
display........how accurate might that readout be?

Thank you Lee Carkenord

Nope in terms of speed. You can check the HR on the TM
easily enough. Either use your own Polar (or borrow one) or
manually take your pulse.

As for the speed, in the lab at school we calibrated the
treadmill every semester. It is pretty easy, just takes a
bit of time.

1) Measure the length of the belt. (I use the metric
system, but if you are Imperial and the readout is
Imperial, you are better off sticking with feet).
2) Place a mark (we used white out) on the platform next to
the belt on the TM (the place where you would straddle
the belt if you were to jump off).
3) Place a mark on the belt itself that is next to the mark
made in step 2.
4) You will need a stopwatch for the next part. Select a
speed to start with (record the speed you set the TM
at), perhaps the slowest speed you normally run on the
treadmill). Once the belt reaches that speed, start
counting how many times the mark on the belt passes the
mark on the platform. Start the stopwatch when the marks
coincide and stop the watch when the marks cross for the
tenth time. Note the time on the watch.

Repeat as many times as necessary at various speeds since
the error can vary. Your TM could be spot on at lower speeds
but off at higher speeds.

Since you know the length of the belt (say 60 feet) and the
speed of the belt from step 4 (if the belt went around 10
times in 1 minute, the belt covered 600 feet per min), you
can then convert that to mph. 600 feet/min *60 min/hour =
3600 feet per hour. 3600 ft/hr divided by 5280 feet/mile
gives you 0.78 mph (okay so that number is not realistic,
but the math works). Let's say you put the TM on 1.5 mph,
you would know you are off by a factor of ~2.

You can then keep a sheet that would tell you that if you
set the TM at 1.5 mph you are really only going 0.8 mph.
From there you can ballpark the speed adjustment unless you
have the means to reset the display.

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

In article
<[email hidden]>, Lee

Carkenord said:

Quoted message said:

The speed in mph of a treadmill........how can I tell
how accurate it is? Is there a general rule like
"usually accurate within plus/minus X percent"........?

Very accurate, probably 1% or so. At least accurate enough
that for the most part, other factors (the fairly
forgiving surface, heat accumultion issues, etc) seem to
play a greater role than miscalibrations.

How did you arrive at 1%? The treadmills we had in our
labs were not used all that often (less than ones in
the recreation center) and we could get more drift
than that in a semester. And these were TMs built by
Quinton which are far better than anything anyone is
going to buy.

Quoted message said:

The heart rate monitors are good, but it's tricky to use
them while youre running.

Cheers,
--
Donovan Rebbechi pegasus.rutgers.edu~elflordOpen ↗

Sam said:

Since you know the length of the belt (say 60 feet) and
the speed of the belt

60 feet?!?! What sort of treadmills do you use?

Paul

Sam said:

As for the speed, in the lab at school we calibrated the
treadmill every semester. It is pretty easy, just takes a
bit of time.

<snip>

Quoted message said:

Since you know the length of the belt (say 60 feet)

That's some size of treadmill!

On a more serious note, I can see an obvious source of error
in this method of calibration in that I'm pretty sure that
most treadmills derive their speed from the rpm of the motor
or belt roller. Belt speed in ideal conditions will = roller
speed but any slippage with introduce inaccuracy. Depending
on incline, speed and weight of runner, the degree of
slippage will vary and consequently invalidate any single
correction factor (unless you really go the whole hog and
calibrate across the full range of speed, inclination and
runner weight combinations).

Of course all the above wouldn't be a problem if treadmills
directly measured belt speed via optical or other motion
sensing systems. I guess manufacturers don't bother with
this as measuring motor/roller speed is easier/cheaper and
to be honest, is good enough 99.9% of the time. It's only
when you get mad b*gg*rs who want to set treadmill records
that accuracy really become important. ;-)

Tim
--
Remove the obvious to reply by email.

I just made up a number late at night... get over it.
<[email hidden]> wrote in message
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Quoted message said:

Sam said:

Since you know the length of the belt (say 60 feet) and
the speed of the belt

60 feet?!?! What sort of treadmills do you use?

Paul

The only time a t-mill speedometer is accurate, is when it
says zero. If you start in your living room, never leave
your living room, and finish in your living room, you've
gone nowhere..........fast.