Cycle Computers and Sensor Positioning

[JoniL]

Hi,
I use my Cateye wireless cycle computer all the time and it's great, so great that I recommended it to my mate, who now has the same one. When we're riding alongside or going quick downhill, the speeds seem a little different. I'm wondering if the sensor positioning has anything the do with it? If I put my sensor higher on my fork, wouldn't I record a different speed? We both put the wheel size as 2096 for our 700x23c road tyres when we set our speedos up.
Thanks,
Joni

 

[slowmotion]

The sensor on the fork just detects each wheel revolution. It shouldn't make any difference where the sensor is placed. A possible explanation is that , although you both have the same tyre size, the circumferences may be slightly different due to tyre brand, rider weight, or inflation pressure.

My two cents.

 

[Gerry Attrick]

It's normal to get a little variation. Mrs A and I have Sigmas on our trikes and tourers. We have never yet recorded the same distance whilst out together.

 

[PoweredByVeg]

Hi JoniL

I reckon the "roll out" method is an accurate wayof measuring your tyre circumference in riding conditions.

Put a dot of emulsion paint (washes off) on your correctly inflated front tyre, sit on bike and push yourself forward one or two wheel revs. Then measure between the dots of paint left on ground for your tyre circumference.

You may want to support yourself against a wall (or friend!). Check this against the little table of tyre sizes in the computer instructions and see how much it differs.

Like slowmotion says, heavy rider or lower pressure will affect the radius from the axle to the ground.

Or you could just live with it

 

[jig-sore]

sensor position has nothing to do with it. the magnet will pass the sensor once per revolution no matter where you put it. you tell the computer the wheel size and it works the rest out for you.

the answer to your question... your wheels are NOT the same size (circumference)

i run my 700x23 tyres at 2105

 

[snorri]

Put a dot of emulsion paint (washes off) on your correctly inflated front tyre,

Or use chalk, a little less messy!

 

[JonnyBlade]

I used a wireless unit for a wile but then I bought a bike holder for my Garmin 405. I kept having to readjust the wireless unit or clean the junk off the magnet!

 

[sleekitcollie]

i need to change the battery on my cateye wirless ( unit batt not sensor ) will it keep all my data or will it need to be reset again
im sure its the battery as the screen is very faded (although sometimes not ) and it is recording some times then stops recording

 

[gbb]

i need to change the battery on my cateye wirless ( unit batt not sensor ) will it keep all my data or will it need to be reset again
im sure its the battery as the screen is very faded (although sometimes not ) and it is recording some times then stops recording

If you remove the battery, all data will be lost (i can't say that with 100% certainty, but every computer ive had does lose data.
Not wishing to put a downer on you, but my old Sigma computers just given up the ghost after displaying exactly what you describe. New battery didnt make any difference. Its bugging me now because i'm not clocking my mileage.

 

[iAmiAdam]

Sigma computers have internal memory, so no lose of data when the time for a new battery arrives.

 

[ian turner]

You should be able to reenter the odometer value on the cateye. All the other data is on a per ride basis and should be reset between rides (the average speed changes to E for error after a while if you don't due to maths errors caused by numbers too large for it to handle)

 

[sleekitcollie]

You should be able to reenter the odometer value on the cateye. All the other data is on a per ride basis and should be reset between rides (the average speed changes to E for error after a while if you don't due to maths errors caused by numbers too large for it to handle)

Thanx it's the odometer reading I'd like to keep if possible . All other ride data I normally zero b4 a ride thanx

 

[HLaB]

Thanx it's the odometer reading I'd like to keep if possible . All other ride data I normally zero b4 a ride thanx

There also a Total Travel Time on the Cateye micro wireless which you can renter too and a second bike function but I tend not to bother and just keep a note of the odo.

 

[peelywally]

one bike avoided more obstacles than the other hence it recorded slightly different lengh of journey , even a few yards here and there mount up how much of a difference was it ?