Push bike speedos ?

Hi,

I was toying with the idea of trying out a push-bike speedo on the GPZ,
but I have since heard that it is common knowledge that these can be
used on a motorbike. So I have just borrowed the 'Act' unit from my old
push-bike to try it...

For those not aware, you mount a pickup head on the forks and a magnet
on the wheel, so it passes in close proximity to the head as the wheel
revolves. You then calibrate it by measuring the diameter of the wheel
which you then feed into the computer. The 'Act' unit has speed to one
decimal place, maximum speed,
time of day/date, ETA, odometer, average speed of trip etc...

One problem I noticed was that the computer tends to go to 'sleep', it
shows a fixed speed at times, which does not vary for several seconds.
I have also heard that other similar units do the same. I was also
unable to work out what the maximum speed it is capable of displaying,
but I suspect it will likely be 99.9mph.

Having tried it and satisfied myself that they work, I will now restore
it back to the push-bike. So does anyone have any recommendations for
one of these units?

I looking for a nice big clear display, one that does not fall asleep,
a real time clock and of course it must be robust/waterproof.

 

Us off-roaders have been using them for donkey's years!

The TrailTech Panoram should do you nicely. http://www.trailtech.net/
for details, http://www.off-
road.com/dirtbike/jun2001/jun01etPanoramComp.html for a review.

 

I had one for the Monster. Never ent to sleep, read more than 99.9
Damned if I can remember the brand though. I could have a look if you want

--
Catman MIB#14 SKoGA#6 TEAR#4 BOTAFOF#38 Apostle#21 COSOC#3
Tyger, Tyger Burning Bright (Remove rust to reply)
Alfa 116 Giulietta 3.0l (Really) Sprint 1.7
Triumph Speed Triple: Black with extra black bits
www.cuore-sportivo.co.uk

 

Sigma Sport (http://www.sigmasport.com) have wide range of bicycle-computers
(fx. the "BC800") - that work just as well on motorcycles. They do not 'fall
asleep' and are capable of measuring speeds up to 300 km/h.

Two important tips are:

1) Do NOT try to use the wireless versions on a motorcycle; it will not
work! (Presumably something with the electromagnetic pulses from the
ignition-system?!)

2) Do NOT place the magnet too far away from from the centre of the wheel.
If you place the magnet too close to the rim, it will (at quite normal
speeds) pass the sensor so quickly that the sensor will not register the
magnet - and this will result in false readings.

Feel free to drop by the danish motorcycle newsgroup
(news://dk.fritid.motorcykel) for more info. Lots of people there have
mounted Sigma bicycle-computers (especially the BC800); quite a few of them
have homepages on the subject - and most of them are capable of
communicating reasonably in english/american..!


/Claus - tried the BC800 - and didn't know about warning #2 until I had
expoyed the magnet to the rim... :-(

 

8<

Are you absolutely sure about this?

 

Are you sure?

Square seems more likely.

 

It happens that Old Fart at Play formulated :

Inverse square law!

 

Harry Bloomfield says...

I have a Sigma Sport BC700 fitted to my CB250RS, and had a BC800 on my
KR-1. Both would do what you're looking for and are easy to read at
speed.

 

I have used the Sigma BC800 and BC600 on motorcycles, they will work in
excess of 100 mph (personal experience), up to 300kph (186 mph) according
to Sigma. They do not fall asleep, have a clock, plus numerous other
neat features (max speed, average speed, etc.).

I prefer to simply expoxy (araldite?) the magnet to the brake disc
carrier, and zip-tie the pickup to the fork tubes. I do not use the
magnet supplied by Sigma, but a very high strength rare-earth magnet
from a Sonicare toothbrush head. Using a stronger magnet than the one
that is supplied in the kit allows you more latitude in mounting the
reed switch sensor.

You will probably need to extend the cable from the pickup to the
speedometer head, so unless you are handy doing wiring splices, springing
for the optional extended length cable intended for mounting the pickup
near the rear wheel of a bicycle would be a good idea.

 

Yes - I am absolutely positive about this!

Thinking I was very clever indeed, I mounted the sensor on the fork
(partially hidden under the front fender) and glued the magnet to the rim as
close to the perimeter as possible so that it passed within a few milimeters
of the sensor. Everything looked great - but it did not work as intended.

This problem could probably be remedied by exchanging the standard magnet
for a stronger one and/or replacing the sensor (which is after all only a
simple switch) with the Hall-effect switch mentioned in Simian's reply.

You will however be fine with both the existing sensor and magnet if you
keep them closer to the hub - fx. mounted on the brakedisc (ie. the
'carrier' as indicated in another post!); and placing them closer to the hub
will not not affect the precision negatively (should you wonder about it, as
I did!)

I'll be more than happy to mail you a picture of the magnet still glued 'in
situ' - where it will probably stay until the paint falls off... :-/


/Claus (who gave up on "The Sigma Project" after buying a GPS...)