calibrate cycle computer

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calibrate cycle computer

Postby HairyMary » Sat May 19, 2007 7:43 pm

hey all.

ive searched for this topic & not really found what i was after so im posting a new thread.

i just bought a cycle computer. im running 26" rims + 1.5" tyres (there about). ive calibrated the computer accordingly + entered the appropriate wheel factor (according to the chart supplied).

the thing is that when it came time for mounting the sensor on the fork & the tracker on the spokes, the instructions contained no detail on how far away from the rim / hub i should place them. to my mind, placing them too close / not far enough would change the distance travelled by the tracker which would then give an inconrrect reading.

my question, therefore is where on the spoke do i place the tracker & the sensor thingo to ensure accurate readings are obtained by the computer?

thanks v much.
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by BNA » Sat May 19, 2007 8:03 pm

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Postby MountGower » Sat May 19, 2007 8:03 pm

A
Last edited by MountGower on Mon Feb 14, 2011 5:05 pm, edited 1 time in total.
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Postby stated » Sat May 19, 2007 8:14 pm

This is a good question, I am a noobi but here goes,
it either doesn't matter, or just move it as close to the rim as you can, maybe move it all the way to the top and then all the way to the bottom and see if there is any noticeable diff in speed.
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Postby europa » Sat May 19, 2007 9:28 pm

The sensor counts the number of revolutions and the rate of those revolutions. Therefore, it doesn't really matter where on the wheel the sensor sits. However, the closer to the hub, the slower the speed of the magnet past the sensor ... so the advice is usually to put the sensor as close to the hub as possible. In practice though, you'll find that to actually get everything to fit, you'll wind up with the sensor out near the rim.

Now, talking real world.

You'll probably be forced to place the sensor (and hence the magnet) just clear of the brakes - this is out near the rim. A bit of messing about on your bike will soon show you why you wind up here - that's where the room is. Nor is it unusual to find that to get the magnet on the wheel to actually clear the magnet (as opposed to hitting it), you'll have it twisted on the spoke. This DOES NOT matter.

The sensor is just that, a sensor. Fit it securely and safely ie, you aren't going to go knocking it. The thing that clips to the spoke, no matter what it looks like, is no more than a magnet - it may not look like one depending on the plastic housing the manufacturer has provided. To get accurate and reliable readings, all you need to do is to set the magnet to pass through the centre of the sensor (critical) and as close to it as possible - on two of my bikes, the magnet is clipped to the spoke but angled backwards to allow it to miss the sensor.

Just make it all fit neatly on your bike and it will work. It gets no more complicated than that. Seriously.

Richard
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Postby HairyMary » Sat May 19, 2007 9:40 pm

excelent guys. thanx v much for the help. ive got the magnet set with about 2mm clearance from the sensor and it seems to be working fine
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Postby europa » Sat May 19, 2007 9:59 pm

HairyMary wrote:excelent guys. thanx v much for the help. ive got the magnet set with about 2mm clearance from the sensor and it seems to be working fine


Getting the magnet to sweep the centre of the censor is more important, and the closer the two pass the better. As long as it's working, it doesn't matter. If it doesn't work (like one of mine didn't the other day), it's a matter of either closing that gap or making sure the magnet passes the centre of the sensor (my Polar cadence meter is particularly sensitive to that though it was my Sigma computer that needed adjustment for this the other day).

Richard
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Postby stated » Sat May 19, 2007 10:11 pm

i got a sigma and i noticed it takes about 18 seconds for the cadence to respond when i pedal faster, but when i stop pedaling it only lags for 1-2 seconds, is that normal. I find 18 seconds very laggy.
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Postby europa » Sat May 19, 2007 10:14 pm

Same with my Polar CS200 mate. Bit frustrating at times but I've got around that by predicting what it should read, then seeing if I've got it right - make a game of it. Bit annoying when you've stopped pedalling for some reason and want to see what you've started again at.

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Postby stated » Sat May 19, 2007 10:16 pm

Thats cool then, cheers.
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Postby HairyMary » Sun May 20, 2007 1:04 am

i s'pose the only way to take care of the lag is to use a wired set-up. i think that the wireless set-ups will need a small gap to recalibrate?
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Postby stated » Sun May 20, 2007 9:51 am

Mine is wired... model 1606L.
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Postby heavymetal » Sun May 20, 2007 10:42 am

If you fit 2 magnets, you get double your speed :D That's how Richard gets his high speed readings :D (I think he may have 4 fitted now).

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Postby mikesbytes » Sun May 20, 2007 11:20 am

heavymetal wrote:If you fit 2 magnets, you get double your speed :D That's how Richard gets his high speed readings :D (I think he may have 4 fitted now).

Kev.


But what happens on the corkscrew when he gets a point where the bikes starts to roll backwards?

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Postby heavymetal » Sun May 20, 2007 1:17 pm

mikesbytes wrote:But what happens on the corkscrew when he gets a point where the bikes starts to roll backwards?


He gets to hold the world's fastest speed record for a bicycle in reverse :D
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Postby europa » Sun May 20, 2007 3:12 pm

Pah. Heathens. I don't need to use magnets at all - I turn those wheels so quickly they generate speed readings without them :shock:

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Postby stated » Sun May 20, 2007 5:41 pm

Getting the magnet to sweep the centre of the censor is more important, and the closer the two pass the better. As long as it's working, it doesn't matter. If it doesn't work (like one of mine didn't the other day), it's a matter of either closing that gap or making sure the magnet passes the centre of the sensor (my Polar cadence meter is particularly sensitive to that though it was my Sigma computer that needed adjustment for this the other day).

Richard


Well guess what,
I had a look at the magnets and the cadence sensor was slightly off center, I moved it just 2mm and that fixed it. It now only lags 2-3seconds both ways. Thanks for the advice.

Neb.
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Postby europa » Sun May 20, 2007 5:47 pm

My cadence meter didn't work when first fitted. Like you, I only shifted the magnet 2mm and away it went. Bizarre that they should be so sensitive to location. I was concerned at first with how this would pan out in the long term - would I be constantly fiddling with it? But after 1,500 km, I've rarely had a problem and never one that was hard to fix.

**insert erudite observation I was going to make but can't because I've forgotten what it was**

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Postby Mulger bill » Sun May 20, 2007 10:41 pm

Still wondering what government appointed watchdogs of the public morals have to do with bicycle computers :?
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Postby europa » Sun May 20, 2007 10:47 pm

Mulger bill wrote:Still wondering what government appointed watchdogs of the public morals have to do with bicycle computers :?


Probably nothing. What spelling mistake (or otherwise) have I made this time? Or am I off the hook for a change?

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Postby Mulger bill » Sun May 20, 2007 10:53 pm

Sorry, couldn't help meself, it's a bit slow at work tonight...

Shaun
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Postby europa » Sun May 20, 2007 11:08 pm

Mulger bill wrote:Sorry, couldn't help meself, it's a bit slow at work tonight...

Shaun


Well, you may consider yourself amused and me having taken the bait :D

Richard
now get back to work
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Postby Mulger bill » Sun May 20, 2007 11:14 pm

Still waiting for something to happen, oh well, I s'pose I could start on tomorrows programme sheets :roll:

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Postby europa » Sun May 20, 2007 11:16 pm

If you can't create some anarchy, you aren't trying hard enough ... of course, you should ask yourself if it's in your best interests to do so, though I usually resist that particular temptation :roll:

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Postby Mulger bill » Sun May 20, 2007 11:39 pm

Gotta admit, foruming on the Co time aint a bad way to earn the bucks :wink:

Your interview went well I hear?
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Postby HairyMary » Mon May 21, 2007 7:36 pm

ok. heres a nother interesting problem.

rode to work this morning. 45km there. checked my max speed when i arrived (i know its a bit nggggg but who doesn't check out how fast they've travelled). anyway max speed was something like 50km/h. boo-yaaa!
now this afternoon i rode the same route but backwards, got home & checked my max speed and it was 99.99km/h!!!!! now, i know i was bookin' for a while there because the route has some nice downhill stretches but i couldn't honestly say i was anywhere near hitting 100k an our. how the hell would my max have, well, maxed out like that?
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