Bicycle Mechanics - Mounting Polar speed sensor

I can't seem to get my Polar S710 speed sensor mounted properly. I get it into position on my Reynolds Ouzo Comp fork so that the light flashes and the receiver picks up the data, then tighten the zip ties. But once I get out for a ride the receiver doesn't pick up data. The light on the sensor still flashes when I start out but no data is received. It's not a powerline problem, I think I may be shifting the sensor slightly when I tighten the zip ties, or I'm not tightening the zip ties enough.
But what I don't get is how come the light still flashes indicating that the sensor is detecting the magnet? I changed the battery in the sensor just in case but still no joy. Any tips for mounting the sensor securely and accurately to my fork? Thanks.

It doesn't appear that you have a pickup problem but rather a transmission distance and orientation problem between your computer and the pickup. I had the same problem with my 710 and had to mount the pickup quite high on the fork for the system to work. Try to test it by moving the computer very close to the pickup and see if you can get reading when you spin the wheel. If you do, you will have to adjust the distance as I mentioned.

Thanks for the tip.
It is currently mounted quite high, just below the Reynolds emblem on the side of the fork. But I will try mounting it higher. I can only move it a couple inches higher before the brake gets in the way.

I have the same HR/pickup. Even though I consider mine still new (purchased Feb, 03) I had to replace the battery in the pickup. Mine worked fine one day and the next it wouldn't pickup anything. I changed the battery and it has worked fine since. (knock on wood)

Good point, but since the LED is flashing, the battery should be strong enough. Again,try not to mount the computer in it's normal place, hold it in your hand close to the sensor, and spin the wheel. If it still flashes but the computer doesn't work, the battery would be the last non-drastic thing I'd try, before asking for a manufacturers help. In that case, either the pickup or the computer maybe bad. I live in Laguna Hills, probably close to you. You can possibly come over and try your computer with my bike.

Thanks guys, I moved the sensor up the fork as close as I could get it to the front brake and it worked on Sundays ride. I moved it about an inch up the fork and I didn't change the battery. My frame is only 52cm so the distance from handlebar to where the sensor was before is not too large. But I think if I had a larger frame, like a 60cm or something with a long steering tube that I wouldn't be able to get the sensor to work.
Do either of you have the cadence sensor? I was told that it is basically a speed sensor with a dim switch changed inside. If so I would imagine that it could be difficult getting reliable readings as the distance from the receiver would be even greater.

I just set up a Polar s720i on my bike. I also had problems with both the speed and cadence sensors. The monitor was only picking up data part of the time. I found that by putting the monitor, speed sensor, and cadence sensor all on the same side of the bike, I was able to get good transmission. I have all of mine on the left side of the bike so that the cadence sensor won't interfere with the chainrings. Wish they would have this stuff in the manual.

I just discovered another phenomena today. When I newly mounted the speed sensor and handlebar mount, the direction (attitude from horizontal) of the watch was very important, specially in area with some interference, Power lines/transformers - the reading was intermitent. I think that the metal handlebar can weaken the sensor transmitted signal. As an experiment, I put the watch on my wrist, and actually had it further away from the pickup - everything was very reliable. I think that they have Signal to Noise discrimination problem in their receiver and poorly located antena, so the reception is "attitude" sensitive. I'll try to experiment some more, but I have no doubt that they have such problem. I had no problem with the heart monitor portion at all, just with the speed sensor. The s720 maybe improved the design, I don't have that one. What are the stated differences between the s710 and s720?

I found the cadence sensor very hard to get working. The sensor is huge and hangs out a long way from the frame. I mounted it on the downtube at 90º so it sticks straight out toward the crank. The distance from the crank to the sensor is 1.5mm only. Any further and it just doesn't work.

The only difference between the 710 and 720 is the 720 has an Aluminium watch face, instead of plastic.

CHEERS.

Mark

I know this is an old post, but I just wanted to add say that mounting the speed sensor on a bladed fork just sucks. I'm still trying to figure it out. Going to Home Depot later to see what I can buy to get it to stay in a fixed position.

The Polar system comes with little black squares of rubber with an adhesive surface on the back. What I have found to work is this. Place a rubber square on the forks (it can be removed if necessary). Tie the sensor on with the cable ties. Then I place a few drops of liquid super glue on to the cable ties where they touch the rubber square. This hold the sensors in place in any conditions but can also be removed without ever damaging the paintwork.

CHEERS.

Mark

Hey Dutchy,
Thanks for the input, but problem solved. I didn't have to resort to superglue, but rather played around with the zip tie tensions along with the rubber sheets. In addition, I used the magnet that could be adjusted to bias itself towards the transmitter. Been on lots of rides and have hand no problems since.



The Polar system comes with little black squares of rubber with an adhesive surface on the back. What I have found to work is this. Place a rubber square on the forks (it can be removed if necessary). Tie the sensor on with the cable ties. Then I place a few drops of liquid super glue on to the cable ties where they touch the rubber square. This hold the sensors in place in any conditions but can also be removed without ever damaging the paintwork.

CHEERS.

Mark

Hey Dutchy,
In addition, I used the magnet that could be adjusted to bias itself towards the transmitter. Been on lots of rides and have hand no problems since.

I was going to mention this... the little wheel magnet didn't work for me but the big ugly one did.

As far as sensor and watch mounting... a blind monkey could've mounted my 710i in a fucntional manner. No problems at all once I switched magnets. So I guess the lesson is try both magnet types and use the one that works.

It doesn't appear that you have a pickup problem but rather a transmission distance and orientation problem between your computer and the pickup. I had the same problem with my 710 and had to mount the pickup quite high on the fork for the system to work. Try to test it by moving the computer very close to the pickup and see if you can get reading when you spin the wheel. If you do, you will have to adjust the distance as I mentioned.

If you look here (http://groups.google.com/groups?selm=bfd05f16.0302030048.62eaff20%0posting.google.com&oe=UTF-8&output=gplain) they had instructions for increasing the transmitter power on the speed sensor all you have todo is move a jumper. It fixed a similar problem I had with my 720i.

What's the difference between a 710 and a 510?

[QUOTE]If you look here they had instructions for increasing the transmitter power on the speed sensor all you have todo is move a jumper. It fixed a similar problem I had with my 720i.[QUOTE]

I tried to look at the link, but it gets me nowhere. Where is the jumper, inside the transmitter?

Thanks.

I tried to look at the link, but it gets me nowhere. Where is the jumper, inside the transmitter?

Thanks.

Sorry about that here is the exact text that I used.



Inside, the jumper switches between high, medium and low power. With the jumper in the position closest to the edge of the board power is maximum, in the other position medium, and removed is low power.


Yes the jumper is on the inside of the transmitter. Just take it apart like you were changing the battery, it is pretty easy to find.

BTW: Make sure to ground yourself before and possibly while handling the board.

[QUOTE]If you look here they had instructions for increasing the transmitter power on the speed sensor all you have todo is move a jumper. It fixed a similar problem I had with my 720i.[QUOTE]

I tried to look at the link, but it gets me nowhere. Where is the jumper, inside the transmitter?

Thanks.


I have a similar problem. I found this alternate link (http://www.pursuit-performance.com.au/polar/html/local/faq/faq_speed_cadence.html) showing repositioning of the jumper to increase transmitter power. I just made the swap and will reinstall the speed sensor before my next ride to see if it works better.

I have a similar problem. I found this alternate link (http://www.pursuit-performance.com.au/polar/html/local/faq/faq_speed_cadence.html) showing repositioning of the jumper to increase transmitter power. I just made the swap and will reinstall the speed sensor before my next ride to see if it works better.

FWIW, with the jumper in the alternate position my wife's Polar S720i has no problem picking up the signal from the transmitter which is mounted on the rear seat stay of our tandems, some 30" away from her handlebar-mounted watch position.

I Am Trying To Mount A Polar S150 Sensor To My Recumbent. Can I Splice The Sensor Wire And Add Additional Wire To It. This Way The Sensor Would Reach My Handlebars.

wierd.. I wonder if this is a problem with just the 720's.. I have a 725 with cadence and speed. Installation was simple and I had no problems. Its got to be the same cadence sensor the 720s use...

hm.

I Am Trying To Install The Sensor On A Recumbent. I Need A Longer Wire To Run To The Sensor On The Rear Wheel.

Hey I think this might help you all. A description how to switch a jumper :) (worked for me, but the batery won't last that long anymore :( )
http://www.cyclingboard.com/ftopic229.html