Tandem Cycling - Modifying cycle computers

I read where someone stated that they had lengthened the wires on a cycle computer by splicing in a section of wire. Sounds reasonable to me. Has anyone ever tried joining the 'heads' from two computers to a single set of cadence/speed sensors? I'm thinking about doing so with a couple of Cateye Astrale 8's.

Anybody? Thanks in advance.

Just bought our first tandem Jan. 2. Have ridden about 30 miles so far. Looking forward to many more.

I have lengthened mine considerably with no problem. My computer is a wireless linked to the front wheel, and my stokers is wired (lengthened) with the rear wheel. What you suggest seems like it would work fine.

I have successfully wired two Avocet 45tt's in parallel to one set of sensors. Low temperature solder, a low wattage soldering iron, and thin speaker wire, all available from Radio Shack, make the job easy.

I did have a set up with one group of sensors and two heads, worked just fine, turned out my stoker couldn't have cared less and would just as soon look at my butt. I was a little worried with water ingress into the solder joint so I used a little heat shrink tubing an a smidge of silicon. I found the hardest thing to do was to strip the wires so that I could solder, darn small wire on the cat-eyes.

Has anyone ever tried joining the 'heads' from two computers to a single set of cadence/speed sensors? I'm thinking about doing so with a couple of Cateye Astrale 8's.

I've done it all ways and remain an advocate of having one pick-up per computer vs. slaving two heads off of a single pick-up. With a single pick-up / spliced wire system, if the sole magnet, pick-up sensor, or wire harness has a problem, both computers are worthless.

That said, splicing signal wires isn't hard to do, but can be hard to do well and not all brands of cycling computers have wires that lend themselves to modification. SigmaSports and CatEye are perhaps the easiest to work with. Be sure to check polarization by verifying that all of the computer functions work when making splices before soldering; they're not simple circuits. Also, as someone already mentioned, the key to a successful splice is making it moisture tight, not just water tight. Sweat, fog, etc... will find its way into every nook and cranny and if it gets to your splice you'll lose your signal until it evaporates. Shrink wrap is a must and while sealing the ends of the shrink wrap is a good idea, the better idea is: (a)covering your splice and all exposed wire with a light layer of silicone, then (b) sliding the shrink wrap over that and (c) plugging the ends with silicone before hitting it with the heat source and before the silicone sets up so that (d) the silicone is squeezed into the shrink wrap & wire for a very moisture tight seal.

Back to your set up, you shouldn't need to splice you stoker's computer wires as I believe the Astrale 8's use a rear wheel pick-up. Therefore, the signal wires should be long enough to run from your stoker's handlebars to either the front fork or the brake bridge areas of the rear seat stay without a splice. If routed to the front the sensor can be place on it's own fork blake opposite the captain's with magnets place at 180* or both sensors can be ganged on one fork blade and pulsed by a single magnet. For routing the stoker's pick-up to the rear of the tandem, I usually mount the sensor on the seat stay adjacent to where the brake shoe contacts the rim. You can usually hide the signal wire on the bottom of the stoker's top tube using a slim strip of color-keyed vinyl electrician's tape or, if you have an unusual color or paint job, use clear or black vinyl tape, trimmed down to about 3/8" of an inch width. I invert tandems when installing computer signal wires on the underside of the tubes to make it a bit easier to work with.

Thanks for the tips. I have the tools and materials necessary to solder the frog hair fine wires. Though it has been a while, I have had considerable experience making rather delicate solder joints. TandemGeek, you made agood point about not being hard to do but hard to do well. I hadn't really considered the issue of a single sensor crapping out and rendering both units useless. Another good point. I still need to decide which setup I'm going to use. I am leaning toward independent systems at this point. Lengthening wires may still be a necessity. We'll see.

Thanks again,
Skipper

I have lengthened mine considerably with no problem. My computer is a wireless linked to the front wheel, and my stokers is wired (lengthened) with the rear wheel.

Why would you do such a thing, why not the wireless for the stoker, so you don't need to lengthen anything, and wired for the captain where the wire does not bother? And why would several of you have taken the trouble of lengthening cable, when a wireless computer would have done the trick? Or am I missing out on something? A wireless does not work for the stoker? I was thinking of installing one, my butt is apparently not as good a sight as Teamcompi's, so I was looking for a source of inspiration for my stoker, need 2 km/hr more.

Make sure the signal range is long enough. In most cases is not.

A wireless does not work for the stoker?

There are just a few and they're rather expensive.

Debbie has a wireless Polar S720i which now sell for between $250 and $310 which can be modified to boost the transmission range such that it will transmit from the rear seat stay the the stoker bars. Works great, but if you don't need, want, or use all of the other functions you're spending about $225 - $295 more than you need to for speed and distance measurement.

Cateye also makes a Dual Wireless and Dual Wireless HRM computer that retail for between $129 - $179, but that you can also find on Ebay for about $89. The problem with these is, there were several generations of the computers made until they got it right. I have no idea which ones are being blown out, but I know a lot of the early buyers ended up sending the things back a few times before giving up on the product. However, there are also a few teams using them that haven't had (or at least mentioned) problems.

FWIW, I run a Ciclosports HAC4 on the front of our tandems and there are no interference problems with Debbie's S720i.

There are just a few and they're rather expensive.

Debbie has a wireless Polar S720i which now sell for between $250 and $310 which can be modified to boost the transmission range such that it will transmit from the rear seat stay the the stoker bars. Works great, but if you don't need, want, or use all of the other functions you're spending about $225 - $295 more than you need to for speed and distance measurement.

Cateye also makes a Dual Wireless and Dual Wireless HRM computer that retail for between $129 - $179, but that you can also find on Ebay for about $89. The problem with these is, there were several generations of the computers made until they got it right. I have no idea which ones are being blown out, but I know a lot of the early buyers ended up sending the things back a few times before giving up on the product. However, there are also a few teams using them that haven't had (or at least mentioned) problems.

FWIW, I run a Ciclosports HAC4 on the front of our tandems and there are no interference problems with Debbie's S720i.

We use the Shimano Wireless Flight Deck (I wanted the graphical gearing display) and Polar heart rate monitor for the captain and Garmin Forerunner 305 GPS providing speed, distance, average speed and heart rate for the stoker. I looked at different solutions of wired and wireless computers to get bike and human performance metrics (downloadable to a computer), gearing configuration and heart rate for both parties. This solution is reliable and does not require running wires or worrying about distances or interference between wireless devices. Santana installed the Flight Deck from the factory and I bought the Garmin on Ebay and the Polar at the Bike Shop with a discount. Total cost of the solution was $129 Flight Deck (installed), $249 Garmin (wraps around the stoker handle bar) and $90 for the Polar F5 – total was approximately $500 including tax. Heart rate data and bike performance metrics are downloaded to our PC and we track our routes, distance, average speed, elevation gained and heart rate using the Garmin and Motionbased software as well as Polar's HR performance website.

...and Garmin Forerunner 305 GPS providing speed, distance, average speed and heart rate for the stoker.

You'll forgive me for not recognizing the GPS revolution. I haven't made that jump as we're still amortizing the investment made in the HAC4 and Polar S720i a few years back.

That said, several folks have gone the GPS with whom we ride and they seem like a slick way to collect, display, and record a lot of data and the navigation stuff is very interesting. I've often thought about picking up something like the Garmin 305 predicated on the ability to use in our cars as well as on the bikes. However, I've promised to start beefing up our retirement account so that may not come to pass either.

Cateye also makes a Dual Wireless and Dual Wireless HRM computer that retail for between $129 - $179, but that you can also find on Ebay for about $89. The problem with these is, there were several generations of the computers made until they got it right.

My single bike has a Cateye wireless that simply stops working when I use it with my headlight (Light & Motion lithium ion). Actually, it did the same thing with my old Niterider headlight. I ride another bike at night, wanting to get a bit more use out of the Cateye before replacing it. I got the Cateye wireless in July 2005, and I found out from others that they were having similar problems with Cateye wireless computers purchased about the same time. A LBS Cateye dealer told me that he still cannot recommend Cateye wireless setups. Just an opinion, I'd guess based on product returns.

For our tandem we decided to go with a wired Cateye for the stoker -- along with wired Flightdeck for the captain. For us this was the most cost-effective and useful solution to get the information we needed and avoid the potential of conflicts with lighting systems. Another choice for the stoker could have been a Garmin 205, but that was still 3-5 times more expensive than the Cateye wired (we don't have S&S connectors, so wired works just fine).

several folks have gone the GPS with whom we ride and they seem like a slick way to collect, display, and record a lot of data and the navigation stuff is very interesting.

One nice thing about the Edge 305 is the range. The cadence sensor can be mounted on a tandem's rear wheel and it can transmit to the captain's bars. It is also able to handle 3 different bikes so I have replaced all my other computers with just this one.

TandemGeek,
I am not sure if the 305 has mapping so I do not know how useful it would be in your car. We have a Garmins Etrex Vista Cx that does mapping. I use it for hiking, biking and in the car. The maps are extra, I have Topo and one of the street maps. Topo might be all you need. As much as you seem to like data, you would love one of these.

Jack

edited to add: Vista does NOT have cadence or hrm

TandemGeek,
I am not sure if the 305 has mapping so I do not know how useful it would be in your car. We have a Garmins Etrex Vista Cx that does mapping. I use it for hiking, biking and in the car. The maps are extra, I have Topo and one of the street maps. Topo might be all you need. As much as you seem to like data, you would love one of these.

Jack

edited to add: Vista does NOT have cadence or hrm

T'Geek:

The Edge 305 and the Forerunner 305 do not have mapping on the device that one gets with a Garmin configured for navigation. The new Edge 305 has an altimeter feature that the Forerunner does not have such that you get better elevation mapping. Both the Forerunner and the Edge have the same GPS technology.

I find the cost of the electronics frustrating and lack of tandem specific solutions an added complexity. However, I think that good bike performance feedback is money well spent if one wants to improve performance and it is cheaper than buying carbon, titanium or magnesium parts.

My single bike has a Cateye wireless that simply stops working when I use it with my headlight (Light & Motion lithium ion).

This is true for just about all wireless components and HID lighting systems that try to co-exist on a handlebar.

The solution for me was mounting my light on my helmet; no more interference. Morever, I discovered that a helmet-mounted light does everything it does well off-road when you're also riding on-road. I sometimes wish motorcycle helmets could legally be used on public roads with an "adaptive" lighting system; it's sure nice to be able to see what I"m looking at when I'm riding my bicycles in the dark, e.g., through corners, off-to the side of the road, down at my computer and bike, etc...

P.S. Thanks for all the tips on GPS. I was sort of joking about that. I'm good with what I have. If and when the HAC4 and Polar die, perhaps a GPS will be of interest. In the mean time, I've got MapQuest and a road atlas for my car and there's almost always someone on big bike and tandem outings with a GPS these days who I can follow around if need be.

Why would you do such a thing, why not the wireless for the stoker, so you don't need to lengthen anything, and wired for the captain where the wire does not bother? And why would several of you have taken the trouble of lengthening cable, when a wireless computer would have done the trick? Or am I missing out on something?

I like to refer to it as tinkeritis. If it's not your bag, don't do it. Sorry about your butt.

throw it all out and focus on your pedal stroke.

My single bike has a Cateye wireless that simply stops working when I use it with my headlight (Light & Motion lithium ion). Actually, it did the same thing with my old Niterider headlight. I ride another bike at night, wanting to get a bit more use out of the Cateye before replacing it. I got the Cateye wireless in July 2005, and I found out from others that they were having similar problems with Cateye wireless computers purchased about the same time. A LBS Cateye dealer told me that he still cannot recommend Cateye wireless setups. Just an opinion, I'd guess based on product returns.

Howdy,

We've got several Cateye Wireless on our singles and they are great. The early ones had problems with the senders failing, but when I bought a bike with a failed sender on it a few years ago, I called Cateye and they sent me a new one at no charge... they recognized they had a problem and fixed it with no questions. Their customer service was top notch, and we've been happy with them since then -- its a good inexpensive alternative.

Steve
Tampa, FL

Howdy,

We've got several Cateye Wireless on our singles and they are great. The early ones had problems with the senders failing, but when I bought a bike with a failed sender on it a few years ago, I called Cateye and they sent me a new one at no charge... they recognized they had a problem and fixed it with no questions. Their customer service was top notch, and we've been happy with them since then -- its a good inexpensive alternative.

Steve
Tampa, FL

Thanks Steve. Were your failures associated with headlight interference or just failures to operate during daylight? Mine works perfectly unless/until I turn on my bar-mounted light. That's when it stops working. Most of the time this happened I had to do a hard reset and went back to 0000 on the odometer.

Since the Light & Motion setup comes with a very long cable, I tried mounting the battery on my seatpost with the light still on the handbar. Still a conflict. As to TandemGeek's recommendation, I will see if there is a problem after I try mounting the light on my helmet -- something that I've thought about for some time. If I can only find that helmet mounting bracket ....

Howdy,

I don't have lights on my bike... it was strictly a hardware failure of the fork sender (which I understand is very common and might explain your LBS not wanting to recommend them).