CATEYE SETUP

[Slave]

I have cateye velo 8.

 

According the the FM (Manual) they do not specify the distance of the magnet from the centre f the hub but the pic shows about three-quaters distance from the hub.

 

The question I have is would I get a different reading if I placed the magnet and pickup closer to the hub? How would this effect the accuracy of the instrument?

 

I have seen various placings of the magnet and sensor and believe that it should be closer to the centre of the wheel.

[TNT1]

 

closer to center is better, but the distance between hub and rim being small and speed generated on a bicycle - again being relatively small -  makes the differential in accuracy vs placement negligible

TNT12008-10-10 07:39:51

[SwissVan]

 

I always put my magnet as close to the rim as possible to gain as much advantage from the Centrifugal force effect, so if I put it closer to the hub will my average speed increase? <?: prefix = o ns = "urn:schemas-microsoft-com:office:office" />

 

 

Druk! Hit the off button to shut down and leaving the office now

[markStockton]

last time I checked 1 rpm (revolution per minute) was 1 rpm  irrespective of what distance from the center of a wheel that you measure it.  

[Slave]

Thanks TNT1.

 

The equipment is obviously designed to read the speed of the magnet where ever it is placed on the spoke.

 

It just seems to me that the speed of the magnet closer to the outside will be faster than closer to the inside of the wheel.

 

Do you have any idea of how accurate these things are. I know it depends on tyre size, rim diameter and setup, but I have mine set for 700 by 23 c which is the correct setting formy rims and tyres.

 

I am interested to know how close to true speed it reads.

[TNT1]

 

 

 

It just seems to me that the speed of the magnet closer to the outside will be faster than closer to the inside of the wheel.

.

 

ya, and the idea behind that being better is that it gives the little brain of the puter more time to compute before recieving the next signal, hence a more accurate reading

 

[TNT1]

 

 

Do you have any idea of how accurate these things are. I know it depends on tyre size' date=' rim diameter and setup, but I have mine set for 700 by 23 c which is the correct setting formy rims and tyres.

 

I am interested to know how close to true speed it reads.

[/quote']

 

I'm using a Delphi 5.0, and it is almost spot on with my GPS both on and off road...

 

[Slave]

This logic of 1 rpm is indisputable, no matter how far from the centre the magnet is placed.

 

However, the magnet has to travel a greater distance around the outside of the wheel than it does closer to the centre. Therefore the magnet speed is higher as it passes the sensor (At the outside of the wheel) and it is possible that it may effect the accuracy.

 

My previous cateye was one of the older models that had a magnetic strip around the very base of the spokes at the hub. I still have no idea how much better that system was from an accuracy point of view, but it left little doubt as to setup as there was only one possible setting.

 

 

[SwissVan]

last time I checked 1 rpm (revolution per minute) was 1 rpm  irrespective of what distance from the center of a wheel that you measure it.  

 

Damn there goes my theory  

 

Yeah Spot on Mark

 

 

[TNT1]

 

 

My previous cateye was one of the older models that had a magnetic strip around the very base of the spokes at the hub. I still have no idea how much better that system was from an accuracy point of view' date=' but it left little doubt as to setup as there was only one possible setting.

 

 

[/quote']

 

Hey, I had an Avocent or something used the same system... piece of cr@p it was... would never work for long...

 

[Johan Bornman]

The pickup doesn't meet the speed of the magnet but how often the magnet switches a reed switch per minute.

A reed switch ....look it up on Wiki, they do a better job than me. However, the computer just sees a bunch of on and off signals coming from the pickup and counts how many of those there are per minute and then multiplies it with the circumference of your wheel.

 

A reed switch bounces a little bit after it has closed and the circuitry has some intelligence in there to only pick up the proper signal and not the bounces. All this happens before the magnet comes past again.

 

So, go with TNT's Marc's advice and believe him whe he says that it doesn't matter where on the wheel you put the magnet.

 

 

Johan Bornman2008-10-10 08:30:45

[SwissVan]

 

What a relief, thought I was going to have to readjust all my magnets...

 

 

[Slave]

I'm with you there Swissvan.

 

What a relief. Adjusting the magnet is the easy bit. It's moving the sensor that turns me into a jibbering nervous wreck.

 

That magnet goes past the sensor quite a few times a minute when you get to go some of the hills around my area.

 

One such mine shaft is called Camaro and my best speed down Camaro is around 94.

 

Now Metro have put up a permanent Camera to catch the speedsters. Wonder if the bike will trigger the camera.

 

Plan on doing a 50k cycle later today and will try to see what speed I can get on Camaro. Problem is I dare not turn around and smile for the camera at that speed.

 

What are some of the max speeds you guys have "clocked"?

[Sammajoor]

 

I'm with you there Swissvan.

 

What a relief. Adjusting the magnet is the easy bit. It's moving the sensor that turns me into a jibbering nervous wreck.

 

That magnet goes past the sensor quite a few times a minute when you get to go some of the hills around my area.

 

One such mine shaft is called Camaro and my best speed down Camaro is around 94.

 

Now Metro have put up a permanent Camera to catch the speedsters. Wonder if the bike will trigger the camera.

 

Plan on doing a 50k cycle later today and will try to see what speed I can get on Camaro. Problem is I dare not turn around and smile for the camera at that speed.

 

 

 

What are some of the max speeds you guys have "clocked"?

 

102k down the"steps" on the fast one,......................... Gives a new meaning to k@king yourself on a bike.  I had a bunch behind me trying to bridge the gap to the next bunch.  We did bridge the gap, but I knew if something went wrong I was going to end up in wards 5 6 and 7 in the hospital

[Slave]

You only end up in  a few wards of the local hospital when one of the big truck drive over you after you fall.

 

The thing that scares me about falling are the roasties (or tar burn if you like.)

 

Tar is amazingly abrasive and removes great quantities of skin.

 

My SO keeps on at me about how I will look if I fall of on Camaro and I keep saying that I hope that I know nothing about it if this does happen.

 

I'm a big sissy and don't like pain.

 

Jeeeeesh, 102 down the steps is pretty fast. My current speed record there is about 65.

 

This is why it is such an issue for me to get a new bike. I want to go faster downhill than I can at the mo'. I can go faster on flats as well although I am happy with my uphill speed.

 

Handling becomes an imperative at these higher speeds.

[Sammajoor]

With my weight getting those speeds down hill was not a problem it was the drags that totally killed me