Tony Smith wrote:
>>> The most complex part about this is going to be the detection of RPM.
>>>
>>> One option is to use a reed switch mounted near the spokes and a
>>> magnet mounted on the spoke itself.
>>>       
>> A reed switch is not a good choice.  This is usually done with a permanent
>> magnet between two spokes of the back wheel as far radially outward as
>> possible and a pickup coil on the frame.  A little analog electronics and
>> you get a pulse into the PIC once per wheel rotation.
>>     
>
>
> You'd better let the bike industry know, everyone uses reed switches.  
>
> And everyone puts them on the front wheel.  
>
> Of course 'everyone' means 'nearly everyone' as no doubt there's a few
> oddball solutions that are more expensive and don't work any better than a
> reed switch that you just might be able to buy.  Maybe someone still makes
> the old mechanical type.
>
> You can buy them for $5 off eBay anyway.  Clock, odometer, trip distance &
> time, current, max & average speed, RPM, wheel size etc.  
>
>   
Yes he could but he wouldn't learn near as much.
Jim

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