Bicycle Speedo Mounting Issues

[Anonymous]

For all of the guys who have mounted a bike speedo/computer on their bikes. I am mounting a Sigma BC1600 on my 82 1100E and have some questions:

1) how did you mount the magnet? I bought the model with a cadence feature and the cadence magnet will likely mount witha tie-wrap at the point where the cast spokes cross on my wheel. It looks like the best choice so far unless someone has a better idea.
2) How did you space the sensor out from the fork leg to get close enough to the magnet? My instructions say a 5mm air gap, but that is going to be a problem for me.
3) The sensor wire is looking like being several inches too short. Can I just cut and splice in an extra length? Is it simply a single conductor wire? I think it should be, but I would hate to cut it and find out I was wrong...


Thanks,
Mark

[duaneage]

I would mount the pickup low, close to the axle. This minimizes the weight effect of the magnet ( you will still need to check the balance). You could use an epoxy glue to attach it.

You'll have to get creative with the pick, maybe a piece of sheetmetal or something like that. Mount it in front of the fork so if it comes loose it will not get trapped between the wheel and the fork and cause a problem.
The wire is the same as what is used in cheap headphones. It can be wpliced, but you have to solder it and be careful. Heatshrink the splice after your done.

[silverhorse47]

I epoxied the magnet to the rim of the wheel and mounted the sensor on the inner fender. I used a cheap ceramic magnet about 1/2 inch in diameter and about 3/16 thick. It has been on there a long time. With the bigger magnet you have less worries about the sensor not picking up the signal at speed.

I got three of the units on ebay for five bucks, and ruined the first one mounting it on the fork near the axle...I also tried splicing the wire and I would suggest that you cannot do it. I certainly failed, anyway. There are two small wires inside each half of the sheath and both are very fine twisted strands, think five hairs on your head each. Even if you succeed in soldering them successfully you will have trouble making a strong enough connection to overcome the weakness of the wire itself. It has no tensile strength of it's own.

The cadence sensor...is for reading how many revolutions per minute your pedals are going around on a pedal bike. Why would you want one on your motorbike? I cut mine off. I also cut off the tac wire and sensor, as I only needed the speedometer function.

Don't worry about using the epoxy. Just get one that is a bit of a gap filler, and make sure the magnet lines up parallel with the sensor. I used a shim right inside the sensor to clamp the magnet to the rim while the epoxy cured.

Good luck
S.

[bgmart450]

They do sell extension kits for the Sigmas (IIRC).

I put 2 rare earth magnets (Radio Shack) on the inner portion of the disc. They are REAL strong and despite the fact I lost the outer magnet, probably when I covered it, I still get readings fine. The gap between the sensor and the magnet is a bit over the 5mm you mention, eyeballed.

I epoxied the pickup to the fork with some cable wrap to hold it still until it set. LOTS OF THEM.... then I started cutting them off one by one day by day (I wanted to be sure).

Haven't had any issue so far. I did this just before last riding season.

[HiSPL]

I put a rare earth magnet out of an old hard drive on the brake disc spoke and used zip ties to mount the sensor. I epoxied the magnet in place too.

The wires can be soldered if your careful...