I've had them on five different bikes now and they work really well.
Unless you have standard, round handlebars (like on a GS), it can be a little tricky mounting the display. I've had good luck cutting the curved part of the back down with a Dremel tool and then using self adhesive heavy duty velcro (called Dual Lock - available from Rider Wearhouse) to fasten the display to a conveniently located surface on the bike. It's really cool to make it a 'heads up' display by mounting the display high on the windshield where you hardly have to glance down from the road to see it.
The other thing that you'll have to do is lengthen the cable between the pickup and the display. This is an easy job if you're handy with a soldering iron and heat shrinkable tubing. I usually use the smallest gauge zip cord I can find (preferably black), but you can use small gauge round wire also. Polarity is not an issue.
Always make the splice longer (a lot longer) than you think you're going to need. I don't know where the extra length goes, but it vanishes when you finally get the thing mounted and all the wiring secure.
I usually just use zip ties to fasten the pickup to the fork tube. Sigma pickups are designed to be zip-tied to bicycle forks, but motorcycle forks are so much larger in diameter that you have to use a wider zip tie to have one that is long enough. I usually open up the little zip tie slots in the pickup base with a fine file to make it wide enough for a larger zip tie.
You'll need a magnet on your wheel to trigger the pickup each rotation. I usually use rare earth magnets from Radio Shack because they are tiny but very powerful. These magnets are about 1/8" across, but they are enormously strong and trigger the pickup reliably even if the gap is a little wider than Sigma specifies. I have epoxied the magnet to an appropriate location on the brake rotor on some bikes (obviously not where it will contact the brake pad...) and have put it in the Torx recess of the rotor mount bolts on other bikes. A little hot glue, epoxy, JB Weld, epoxy putty - whatever will keep it from moving around - and you're ready to go.
The display is calibrated by measuring the wheel circumference and entering it in millimeters, if I recall correctly. It's pretty easy to make a chalk mark on your sidewall and then roll the bike on the garage floor until the chalk mark is down again, then measure the distance between the marks. Keep in mind that this is only an estimate - you can 'dial in' the calibration by comparing your trip odometer reading to known distances (like mile markers) as you ride.
If you set the trip odo to zero at a mile marker along the side of the freeway, for example, then ride 20 miles according to the mile markers and your Sigma indicates 22 miles, decrease the number entered as your wheel circumference by 10%, then try again. I've gotten mine as close as 1% error and figured that was close enough.
The Sigma cyclocomputers are really accurate (supposedly to 180 mph or some ridiculous velocity like that) and have a dizzying array of features and statistics that you can read out - current speed, average speed, maximum speed, riding time, distance ridden today, trip odometer, total odometer, stopwatch, current speed compared to average, etc, etc.
The cyclocomputers are not backlit, although Sigma makes a little battery powered light that you can mount next to the cyclocomputer to illuminate it. I haven't tried this, although I've been meaning to make one with an LED to illuminate the display at night - those little flexible lights for illuminating a GameBoy look perfect. I nearly always look at the Sigma instead of the speedometer on the bike and I feel compromised at night when the Sigma isn't visible.
If anyone has tried using a wireless cyclocomputer on a motorcycle, I hope they will post their experience here. It would be really nice if that would work, but I suspect that electromagnetic interference from the ignition system would keep it from working or being reliable.
Good luck - drop me a line if I can answer any questions. Better to use conventional e-mail than the PM function from this forum. I haven't gotten accustomed to checking for those PM's yet.
REI sells the Sigmas also, but the one from Rider Wearhouse with an extra long pickup cable could be a real bargain if it is actually long enough to use on a bike. I guess they will have figured that out, eh? The one in the catalog looks like a BC800, which isn't the top of the line, but will do everything you want to do and more. $23 is a very reasonable price for it.
Sorry to be so long winded, but hopefully this will have answered your questions better than saying: "Yeah, they work great."
Sigma BC1400 on an R1100GS
Here's a picture of a Sigma BC1400 on my R1100GS - I hope (just figuring out how to attach pictures...)
Sigma pickup on an R1100GS
Cool! First picture worked! Here's the pickup on the fork leg. Rare earth magnet is just to the left of the pickup.
Sigma on an ST1100
Here's an installation where I ground the back of the handlebar mount for the display flat and then used adhesive Dual Lock hook fastener to mount it on a bracket fabricated to attach it to the brake master cylinder mounting bolt.
The bracket is large enough to hold the Sigma speedometer and a timer.
I first learned of this from a VTX website. We have a K75RT with an intermittent speedo unit. The Sigma Sport is considered the model of choice due to its ability to handle the speed of a motorcycle. I understand those who have tried the wireless unit gave up.
On the K75RT there is a plastic-coated foam dash unit to mount extra switches. We popped one of the plugs out of this and stuffed the Sigma unit there. It was tricky to get a tie off through this, but it sits flush and looks great. I've heard that in the bright sun if the unit gets hot the screen will go black but with air flow that clears right up.
We haven't finished the installation; still messing with how to mount the magnet and sensor. Our bike has the removable brake covers, so we still have to figure out how best to mount the Sigma parts without affecting the serviceability of the various front end parts.
Here's the K75RT switch panel:
We just recalled how that Sigma is mounted on our K75RT. Since there is no connection to the handlebars, we used one of the supplied rubber bands and a disassembled wooden clothes pin, then put one of the clothespin pieces as the crossmember, behind the foam dash.
On the Road
I put a Sigma on a K1100RS & am very pleased with it. I like the easy read & rarely look at the stock speedo now. By doing a search on the internet for the Sigma I was able to find them for $14 at a bike shop in TX. (I can't remember the place now & the receipt is at work or I would post a link)The IBMWR site has instructions for installing.
Last edited by 104857; 08-26-2003 at 02:13 PM.
I also have a Sigma, and have been very pleased with it for the three years that I have had it. Mine is the BC 800 and was purchased at a local bicycle shop. I would also like to echo the recommendation concerning the lengthening of the wire. I first measured and added a length of wire which I knew would be long enough, but I was wrong. IÔÇÖve heard that they offer a kit for mounting it to the rear wheel of a bicycle, which I believe it may just have a longer wire included. It took me a little while to decide exactly how and where to mount the pickup. I was probably being a little too picky trying to find the best way. I initially thought the display was too small and would be a little hard to read while attached to the handlebar, but I have no problem. It did take a small amount of tweaking and test rides to get the accuracy just right, but it is right on with my GPS that IÔÇÖve had for about eighteen months now. In one way itÔÇÖs actually more accurate than the GPS. The information it gives is more of a constant or real time, whereas if I remember correctly my GPS updates about once every second. I notice this more the quicker I accelerate or decelerate. I do wish it had a back light, though I have not experimented with any type of external lighting. The amount of information it provides is a lot more than I had expected or was aware of when I bought it. When I bought my GPS I thought I would have no use for the trip computer on the Sigma, but believe it or not there are times for me to use both. Mine has performed flawlessly, and I still find it hard to believe that they are so inexpensive. In my opinion, the trip computer alone is worth the price of admission. If you just want to check them out, stop by any real bicycle shop. They should be familiar with all of the Sigma models. My local shop even dropped the price a few bucks after I told them how much my motorcycle buddies were paying for them elsewhere.