Installing Polar power sensor on Orbea Onix

pinoybiker

Hi to all.
Any Orbea Onix being fitted with Polar power sensor?
I am planning to have the S725 and the power sensor. But having read the various threads about the difficulties encountered in installing the power sensor on the chain stay make me post this question to those who have an Onix with the Polar sensor installed.
The crank is FSA SLK double compact crank, 12-25 cassette.

It seems the installation is complicated but i dont have the choice of having the other brands. Not enough dough left for those other higher price brands.

Did the set-up worked properly with no additional tweaking of the sensor, cadence magnet, etc every now and then?

JTE83

The Orbea Onix has a chainstay that looks like any other bike, so installation is the same as any other bike. Use the rubber pads to raise the sensor close to the chain when it's in the low cog / small chainring combination. Then glue a round cylindrical magnet to the end of your right crank pedal for the pedal cadence magnet. Get this magnet from Home Depot or any hardware store. Next, install the speed sensor on the down part of the chainstay, not on top. If you put it on top sometimes the wheel will deflect, then the spokes will rip into the speed sensor and destroy it - this happened to me and it was a $30 repair from Polar USA.

I have 2 bikes with a Polar Power Output kit. My power readings are kind of high / incorrect when using a 53 - 21, 24, or 27 combination. I don't get bad readings from an 11-23 cassette.

pinoybiker

Hi JTE83 and thanks for the reply. So sorry for my late reply as i got no access for quite some time. My job entails me not to have daily access on the internet. Or should i say months. Do they have internet access on outer space.
I put an order on the Polar unit today and i should have it next week. I can see that the clearance between the chain and the right crank is quite small on the big ring/small cog combo. did you install your cadence magnet on the hole where the pedal fastens the crank. It should get right inside that space flushed with the crank arm. Otherwise if it protrudes on the crankarm i may need a very thin magnet, right? I am using a 12-25 cassette right now and i dont normally use my 50 on 21/23/25. Am planning though to get an 11-23 once i get hold of the 404 wheelset.
BTW the manual says the infra red works on Windows 95 only. Does it not run then on XP? Am always on the move and using a laptop more than a desktop so the built-in infra red is very convenient.

JTE83

Yes, I put the cadance magnet on the end of the pedal / stick out of the hole in the crank. Sorry for the 11-23 cassettew misinformation - my two bike that use the Polar Power Output kit use a 12-25 and a 12-27. I just noticed bad (high) readings on my 2005 Kestrel Talon with the 21, 24, & 27 cogs. My other bike, a 2002 Giant TCR Aero 2 with 12 -25 - I haven't used in a long time so I don't remember if it has bad readings in the lower cogs. I guess I should give it a test. My 11-23 cassette is on a 2003 Cervelo Soloist Team with no power output kit - maybe I should try this wheel on my Kestrel.

My infrared USB works on Windows XP.

Are you living in the Phillippines right now?

pinoybiker

Thanks your last.
I think i wont have much problem on installing the Polar kit. I can manage spending some time on its installation as i know its not so easy to get it running good/right. Infrared-thats a good info as i dont have to buy the Polar infrared.
Boy youve got quite a collection of bikes! I like the Soloist but could not get my size so settle for the Onix instead.
Yes i am but currently out of town. Thats precisely the reason why i didnt get the other brand/PT as i could not afford to have it calibration after a few years of use. No service on my area.

rltaylor

I installed a Polar power system on my Orbea Onix. I had a lot of difficulty positioning the power/cadence sensor but I think most of the difficulty arose from my triple crankset. I don't think you will have as much trouble, perhaps none, with a double. I ended up making a little wooden bracket/shim to position the sensor correctly. Once positioned properly, it works well.

I encounted another problem after the installation that had nothing to do with my particular bike. The electrical contact / mounting system is poorly designed. When one places the wrist band around the bike mount bracket, it is difficult to get a tight fit. Road vibration frequently causes the electrical contact to be disrupted intermittently. I read about this problem and tried a solution described by others on the net. After placing the wrist band around the bike mount, I place a small wedge shaped piece of wood between the wrist band and the bike mount that stretches the wrist band tight. This completely eliminated my intermittent electrical contact problems.

BobT

pinoybiker

Good day BobT and thanks for the advise.
I have put an order already and expect to have it by next week.
Was the sensor useable on all the gear combinations? I have a double though and yours is a triple. How did you mount the magnet? i dont intend to use the original magnet though. Ill see once installed if ill be having the intermittent readings. Thanks

__________________
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rltaylor

This sensor works in all gear combinations, even though at the extremes, the distance from the chain varies considerably. With the smallest chainwheel, 30T, and the smallest rear sprocket, 12T, the chain is about 2 mm from the sensor when the chain is tensioned and touches the sensor when there is no chain tension. With the largest chainwheel, 52 T, the largest rear sprocket, 27T, the chain is about 35 mm from the sensor.

I used a Radio Shack rare earth magnet. I stuck it to the inside of the crankarm with double-sided adhesive tape then wrapped electrical tape around the magent and crankarm.

I do not have problems with intermittent readings now that I figured out how to keep the watch/receiver tight against the bike mount / electrical contacts.

BobT