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  1. #1
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    Two Computers on a tandem

    Has anyone had any experience runnig two wireless computers on a tandem ?? Can it be done and if so what computers do you recomend to use and how do you hook it up ???

  2. #2
    hors category TandemGeek's Avatar
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    Yes, we and many other have been running dual wireless for several years.

    The captain's wireless computers are set up exactly the same way as they would be on any other single bike. My SigmaSports HAC4 (high-end wireless HRM) is about 4 years old and, aside a miscalibrated temp sensor, it still works just fine. Transmitter on the left front fork leg & receiver on the bars. My wife's Polar unit -- also 4 years old -- has the transmitter sitting under the rear brake caliper on the left chain stay and the receiver sits on her handlebars. Never any cross talk with the units, although riding past high power lines will send them in RFI world for a few moments and you can't use a bar-mounted HID headlight in combination with a wireless computer.

    A stoker's wireless requires one of three things:

    1. It should be a different brand from the one used in front to improve your chances of avoiding RF interference issues. Polar's high-end HRMs use a technology they call "own code" that randomly locks onto one of 10 frequencies embedded in the chest strap transmitter to mitigate RF cross talk so they are always a good choice if you're running dual wireless. In fact, two Polars can be used so long as at least one of them has the own-code feature.
    2. It needs to have a transmission range greater than 1m, which has limited choices in the past to the high-end Polar HRM units like my wife's S720i, Cateye's DualWireless, and more recently the sub $100 VDO wireless models. However, note that the Polar units are shipped in a mid-range configuration and the transmitter must be opened and a jumper repositioned to achieve the long-range configuration. There may now be others in the sub $100 range as it's been a while since the technology was improved.
    3. It needs to eliminate the transmission range issue by using GPS technology to calculate speed, distance, etc, e.g., a Garmin 205, 305, etc... which are also a bit pricey. On the bright side, with two new models now on the market, I suspect the older models will be getting blown-out by Etailers and the second-hand market will also be flush with them, which is to say prices will be falling on the older units.

    So, it really comes down to budget. Wireless is nice if you have a travel tandem that needs to be taken apart, but can get expensive if you have multiple bikes and don't want to spend the time moving the transmitters and receivers as those suckers aren't inexpensive. Wireless is also a good choice if you're already contemplating the use of a heart rate monitor (HRM). However, a $45 Cateye or Sigma wired rear-wheel unit will do everything that most users need and a strip of vinyl electrician's tape color keyed to your frame will allow you to do a pretty good job of hiding the wire if you run it along the underside of the boom tube with the speed sensor mounted just below the rear brake arms on the seat stay. If you have multiple bikes, a used Garmin 205 might be the ticket since they don't require pick-up sensors or calibration and do some other cool tricks that are only found on high-end bicycle computers.
    Last edited by TandemGeek; 02-23-08 at 05:28 AM.

  3. #3
    Double Secret Probation R900's Avatar
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    We run a wireless Flightdeck upfront, and a wired Cateye in rear. Cable run is fairly simply with a little matching electrical tape. I also use my Garmin on occasion. The speed/cadence sensor fits, but magnet placement on the stoker crank is difficult. I used a super magnet from RS attached with silicon, it lasted a couple months. Transmission was strong enough for front or rear mount of the receiver.
    Time to Ride...

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    Would it be possible to use one sensor and 2 computer heads if they were both the same model and the sensors would read from the distance it was set up at

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    hors category TandemGeek's Avatar
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    Quote Originally Posted by warren goodwine View Post
    Would it be possible to use one sensor and 2 computer heads if they were both the same model and the sensors would read from the distance it was set up at
    There are purportedly two models that will accomplish this:

    The Vetta VL110/T2X series of computers (MSRP $180 - $260)

    The Cateye V-Series coming out this March using Broadband technology ($140 - $180)

    No personal experience, but I believe one of the tandem mags did a review of the Vetta last Spring and it scored high marks. I'm not sure if you would need to buy two of the same model or, for instance, if a lower-end Vetta 110 head would work with the TX2 model's transmitter.

    Of course, the only thing to remember out using a single pick-up -- wired or un-wired -- is that if you have a transmitter or sensor problem, both computers go out. It may not be a big deal, but it's worthy of note.

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    Hello TandemGeek,

    question about the Polar jumper config.

    Which pins do you position the jumper on compared to how it is sold?
    Try to explain and include how you are holding the sensor when you move the jumper unless the pins are numbered?

    I attempted this for my TT bike a year or so ago and had no improvement, and eventually just mounted the unit closer and at an angle or wore it on my wrist on the bottom side so I could glance down and still stay on the aero bar.

    I would like to set up my wifes Polar on the tandem.

    Rob

  7. #7
    hors category TandemGeek's Avatar
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    Quote Originally Posted by robmitchell View Post
    HWhich pins do you position the jumper on compared to how it is sold?
    Try to explain and include how you are holding the sensor when you move the jumper unless the pins are numbered?
    Here's a LINK to the Aussie Polar site that provides the details and a photo of the transmitter with the jumper sitting on the correct pins (middle and furthest from the battery) for the long-range signal setting.

    Yours would have come with the jumper sitting on the pin closest to the battery and the middle pin, which is the medium range.

  8. #8
    Senior Member JTGraphics's Avatar
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    No problem using 2 VDO C3 DS Digital Wireless Cyclocomputer w/ Wireless Cadence computers both units running from one sender these have a 15ft range so signal is not problem, the senders can be on rear or front wheel and cadence can also be on stoker or captains crank doesn't mater. I happen to have mine on rear wheel and stoker crank.
    It may not be fancy but it gets me were I need to go.
    http://www.jtgraphics.net/cyclist_bicycles.htm

  9. #9
    hors category TandemGeek's Avatar
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    Quote Originally Posted by JTGraphics View Post
    No problem using 2 VDO C3 DS Digital Wireless Cyclocomputer w/ Wireless Cadence....
    Interesting reviews: http://www.performancebike.com/pwr/p...s-Cadence.html

  10. #10
    Senior Member zonatandem's Avatar
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    We are decidedly low tech and settle for one computer on our tandem. Seeing that we are both riding the same bike, going at the same speed and to same destination we feel no need to get more info.
    Have not gotten involved with HRMs . . . our hearts beat, we ride. Quits beating? Hey we must be dead!
    Still using a hardwired 'puter, a Planet Bike Protoge 9.0.

  11. #11
    Cyclist- Bike 'n a half
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    Quote Originally Posted by warren goodwine View Post
    Has anyone had any experience runnig two wireless computers on a tandem ?? Can it be done and if so what computers do you recomend to use and how do you hook it up ???
    By most definitions a GPS is a computer, and they're available in wireless. I use a Garmin Edge 305HR that swaps easily between the tandem and my single bike. Stoker has a Garmin eTrex Legend (no single bike).

    I like the Edge because it's so easy to download, save and compare ride data. Stoker likes the eTrex Legend for the display screen that's much larger than a typical bike computer and because the color of the case matches the bike (see below).

    The largest adaptive curve in changing from typical bike computers to GPS is dealing with the batteries.

    The Edge charges off a plug-in adapter or more typically, the mini USB when I plug it into my laptop. If I don't download and leave it plugged in on Saturday night, it's only about 70/30 if it'll run until the end of the ride on Sunday. If I don't plug it in sometime after Sunday's ride "fagetaboutit" for the next Saturday morning. If I let the battery drain it's no big deal, I still get to go for a bike ride.

    The eTrex Legend uses two AA's and gets pretty close to the 18 hours battery life advertised, roughly a set per month if we ride 40 miles every Saturday and Sunday. She keeps a couple of spare sets in the bag under her handle bars and can change them out easily while underway as long as we're not hammering too hard.
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