Polar X-Trainer speed/distance problems

Polar X-Trainer speed/distance problems

Post by Mark Rosenbe » Wed, 05 May 1999 04:00:00


Much as I'd like to believe that I hit a top speed of 60.2 mph on my
mountain bike, and that all of the trail markers understate the mileage
covered, I think it more likely that the speed sensor is malfunctioning.
Anyone else had similar problems?

- Speed seems to jump around more than it should. I see wide fluctuations
  that mostly settle out after awhile.
- Trip mileage is high. Almost looks like it is displaying KPH instead of MPH,
  but the MPH symbol is definitely there.

Relevant details:

- I am using a non-standard magnet on my wheel that is considerably larger
  than the poorly designed (IMHO) one that Polar provides.
- I sent the unit back to Polar. They replaced the battery in the
  wrist receiver, and checked the cyclometer functions. They claim it
  checked out.

--

 
 
 

Polar X-Trainer speed/distance problems

Post by Mike Lutto » Wed, 05 May 1999 04:00:00

It doesn't seem like a bigger magnet would cause that problem. If you spin
the wheel slowly and watch the LED on the sensor, does the light come on
twice? Once when the magnet approaches the sensor and once when the magnet
moves away from the sensor? It sounds like you have some kind of
intermittent problem.

I got two magnets with my XTrainer, a rather large, heavy metal encased
magnet and a smaller, lighter plastic encased magnet. The larger one
actually made a whistling noise when I rode my bike - it's not very
aerodynamic. The smaller doesn't suffer from that problem, but it doesn't
stay in place very well.

The other problem I have is that sometimes the heart rate reads 230 - 240
bpm. It usually occurs when I get my heart rate up to about 160 bpm. So I am
working fairly hard, but the monitor reading will just shoot up to 230-240
bpm. I would be in trouble if my heart rate were really that high, wouldn't
I?

 
 
 

Polar X-Trainer speed/distance problems

Post by Mark Hick » Thu, 06 May 1999 04:00:00

The pickup for bike computers are mechanical reed switches.  The
attraction from the magnet is all that is able to "open" or "close"
the reed switch, so it has to be a fairly flimsy mechanism.

This flimsiness tends to allow the switch to get sloppy when there is
a lot of vibration (i.e. riding off-road) or when the magnet is flying
by at a speed that causes the switch to not fully engage, but to
"bounce".  This sends multiple "pulses" to the computer sometimes,
upping the apparent speed.

Some computers are better at filtering this out (they're smart enough
to ignore a series of pulses that tell the computer that the bike
accellerated from 20 to 80 and back to 20 in what appears to be three
or four revolutions).

Mark Hickey
Habanero Cycles
http://www.cynetfl.com/habanero/
Home of the $695 ti frame

Quote:
>Much as I'd like to believe that I hit a top speed of 60.2 mph on my
>mountain bike, and that all of the trail markers understate the mileage
>covered, I think it more likely that the speed sensor is malfunctioning.
>Anyone else had similar problems?

>- Speed seems to jump around more than it should. I see wide fluctuations
>  that mostly settle out after awhile.
>- Trip mileage is high. Almost looks like it is displaying KPH instead of MPH,
>  but the MPH symbol is definitely there.

>Relevant details:

>- I am using a non-standard magnet on my wheel that is considerably larger
>  than the poorly designed (IMHO) one that Polar provides.
>- I sent the unit back to Polar. They replaced the battery in the
>  wrist receiver, and checked the cyclometer functions. They claim it
>  checked out.

>--



 
 
 

Polar X-Trainer speed/distance problems

Post by James Nonnemache » Sat, 08 May 1999 04:00:00

I'll assume the wheel size is properly set?
Quote:

> Much as I'd like to believe that I hit a top speed of 60.2 mph on my
> mountain bike, and that all of the trail markers understate the mileage
> covered, I think it more likely that the speed sensor is malfunctioning.
> Anyone else had similar problems?

> - Speed seems to jump around more than it should. I see wide fluctuations
>   that mostly settle out after awhile.
> - Trip mileage is high. Almost looks like it is displaying KPH instead of MPH,
>   but the MPH symbol is definitely there.

> Relevant details:

> - I am using a non-standard magnet on my wheel that is considerably larger
>   than the poorly designed (IMHO) one that Polar provides.
> - I sent the unit back to Polar. They replaced the battery in the
>   wrist receiver, and checked the cyclometer functions. They claim it
>   checked out.

> --