Bike digital speedo

[Guest]

Heres a stupid question for you guys.

Bicycle digital speedometers! They run off a small magnet that passes a sensor mounted on the forks. Right? SO..... what if someone were to mount one on a motorcycle?!?!

The speed can be adjusted (i think) by moving the sensor and magnet towards and away from the hub. So in THEORY, this might work.... right?

Any thoughts?

[Mark M]

It's been done many times. There are also motorcycle specific speedo/tach units that use the same sensor setup. For instance:

http://trailtech.net/vapor.html

There are a few things to watch for in bicycle computers. Make sure the sensor wire is long enough to reach the end of the forks and make sure it will read to a high enough speed. Some computers will not read past 60mph or so.

Mark

[jmlcolorado]

damn! just when i thought i had an origional idea yeah right.

I think ill look more onto it for my build. Im gonna use a twist type clutch to keep the bars clean. The onlt wires up front will be the headlight wires.

Front brake, hopefully will be the only exposed cable. Clutch and throttle will be run in the bars.

Thanks for the link.

[Nessism]

Bike speedos are calibrated by inputing a distance reference and the computer does the rest- you need to measure how much distance is covered in one revolution of the front wheel. When I do this on my bicycles I put a dab of paint on the wheel and then roll the bike down the driveway. Count wheel revolutions and measure the distance covered with a tape. Very accurate speedo but it's going to look pretty silly on a motorcycle in my opinion.

[jmlcolorado]

Well im not after the looks really. I like the size of it. Very small and clean looking. Though if i wanted looks i could fab up a cool fiberglass case for it and mount the display in there. Heck, i could even paint it in chrome paint

But mainly the compact size and simplicity are my drives for this idea.

Thanks for the input on calibrating them.

[jmlcolorado]

you need to measure how much distance is covered in one revolution of the front wheel. .

So this being said, it doesnt matter where the sensor or magnet is located in relation to the center?

If thats the case that makes installing that much easier!!

[Mark M]

So this being said, it doesnt matter where the sensor or magnet is located in relation to the center?

If thats the case that makes installing that much easier!!

It only has to go past the sensor fast enough to generate a pulse for the counter to see. I have seen magnets mounted on the wheel and on the rotor carrier with no problems.

To get around the max display speed, I believe the Sigma Sport BC1600 computer has no max speed or it is very high.

Mark

[jmlcolorado]

Yeah ive just read that most, if not all "sigma" models carry a 300 km/h or 183 MPH rating. Pretty cool. I think im gonna try it out.
In fact one sigma model even has a backlight for night riding.

[Nessism]

Nashbar.com carries Sigma Sports cyclocomputers... http://www.nashbar.com/results.cfm?c...Cyclocomputers
They have a 15% off coupon available on the site right now which should help with price some.

[hillsy]

Bicycle speedos are used in the streetfighter scene quite a bit. The main problem is they're not backlit, so night riding involves a bit of guesswork .

I've got an Acewell on my ZX9 and FWIW it's awesome. It has speedo, tach and warning lights in the one unit. It's a round "pod" unit - smaller than a tennis ball.

You can also mount the sensor on the rear wheel if you want a cleaner look for the front end - it's just a 2 wire cable which can easily be extended.