Polar Power Sensor Installation

I'm having difficulty installing my Polar power sensor.
I'm not alone. I found a lot of useful information with the help of Google.

My chainstay curves inward so much that mounting the power sensor parallel
to the chainstay, as Polar designed the system, does not work very well.
The front of the power sensor needs to be angled outboard quite a bit to get
the cadence sensor close enough to the crankarm magnet to get cadence
sensing. I think I need to make custom brackets / shims for the chainstay /
power sensor mount.

I found a picture of an installation that does just what I need at
http://tinyurl.com/adn95
I can't find any other detail about how this was done. What would be a good
material to use for the shims and where can I get it?

Perhaps someone has some additional ideas on mounting a Polar power system
on a Orbea Onix (curved chainstays) with Shimano Ultegra 10 speed triple
gearing.

BobT

BobT wrote:
I'm having difficulty installing my Polar power sensor.
I'm not alone. I found a lot of useful information with the help of Google.

My chainstay curves inward so much that mounting the power sensor parallel
to the chainstay, as Polar designed the system, does not work very well.
The front of the power sensor needs to be angled outboard quite a bit to get
the cadence sensor close enough to the crankarm magnet to get cadence
sensing. I think I need to make custom brackets / shims for the chainstay /
power sensor mount.

I found a picture of an installation that does just what I need at
http://tinyurl.com/adn95
I can't find any other detail about how this was done. What would be a good
material to use for the shims and where can I get it?

Perhaps someone has some additional ideas on mounting a Polar power system
on a Orbea Onix (curved chainstays) with Shimano Ultegra 10 speed triple
gearing.

Probably don't want to hear this but get a refund and get a Powertap
Pro rear wheel. More accurate, easier to set up, all around a better
system that relies on chain frequency.

BobT

First,

I have the polar power unit, and it is only slightly less accurate than the
powertap.

There is no rule with regards to the mounting of the magnet, nor what magnet
to use. Try a rare earth magnet. They are very powerful and you can mount it
quite a distance from the pickup and still get a reading.



"Qui si parla Campagnolo" wrote in message
ups.com...


BobT wrote:
I'm having difficulty installing my Polar power sensor.
I'm not alone. I found a lot of useful information with the help of
Google.

My chainstay curves inward so much that mounting the power sensor
parallel
to the chainstay, as Polar designed the system, does not work very well.
The front of the power sensor needs to be angled outboard quite a bit to
get
the cadence sensor close enough to the crankarm magnet to get cadence
sensing. I think I need to make custom brackets / shims for the
chainstay /
power sensor mount.

I found a picture of an installation that does just what I need at
http://tinyurl.com/adn95
I can't find any other detail about how this was done. What would be a
good
material to use for the shims and where can I get it?

Perhaps someone has some additional ideas on mounting a Polar power
system
on a Orbea Onix (curved chainstays) with Shimano Ultegra 10 speed triple
gearing.

Probably don't want to hear this but get a refund and get a Powertap
Pro rear wheel. More accurate, easier to set up, all around a better
system that relies on chain frequency.

BobT

BobT wrote:
I'm having difficulty installing my Polar power sensor.


"Qui si parla Campagnolo" wrote in message
ups.com...
Probably don't want to hear this but get a refund and get a Powertap
Pro rear wheel. More accurate, easier to set up, all around a better
system that relies on chain frequency.

Thanks, but you are right, I didn't want to hear that. In fact, I would
love to have a Powertap Pro (or SRM for that matter) but I paid $250.00 for
my Polar unit compared to $900.00 plus a wheel build. Based on head-to-head
comparisons I've seen on the web, I'm hoping to get reasonable results with
this much less expensive product.

"JayofMontreal" wrote in message
...
There is no rule with regards to the mounting of the magnet, nor what
magnet to use. Try a rare earth magnet. They are very powerful and you can
mount it quite a distance from the pickup and still get a reading.


I tried using several rare earth magnets I purchased from Radio Shack to no
avail. The problem is that the chainstay is 4 cm from the inside of the
crankarm where the cadence sensor needs to be. If I mount the power /
cadence sensor on top of and parallel to the chain stay, I'm going to need a
really strong magnet. In fact, when I put 4 of the 1/8" Radio Shack rare
earth magnets in place, they pulled the chain against the crankarm magnets
but didn't trigger the cadence sensor.

I have reached a solution that I will post here for others who might have
this problem in the future.
For the shape of my chainstay and my chainline (Onix Orbea, Shimano Ultegra
10-speed triple), I need to mount the power / cadence sensor at an angle to
the chainstay with the front of the sensor outboard. I made a spacer that I
zip tied to the outside of the front of the chainstay. I then zip tied the
front of the sensor to the top of the spacer positioning the front of the
sensor much closer to the crankarm. I think one could make a spacer to move
the front or back of the sensor up or down or inboard or outboard.

I made the spacer out of wood. Plastic like Nylon or Delrin might be better
but I couldn't find any locally. First, I measured how much above the top
and how much outboard of the outside of the chainstay I needed to position
the sensor. I used a contour gage to transfer the shape of the chainstay to
a small block of wood. I then used a Dremel tool to shape the inboard side
of the wood to fit the chainstay. I then shaped the upper outboard part of
the block to fit the sensor at the correct position. I cut a shallow
channel for the zip tie. I finished the wood to protect it from the
elements. Now the system works!

BobT