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Garmin 305 - speed sensor

slammy's picture
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started by slammy on October 13, 2008

I am getting an indoor trainer for christmas (I'm getting it now, since the weather is turning bad now), so I'm wondering if a speed/cadence sensor will work indoor on the trainer as well as outdoor during the summer? So can I use the Garmin forerunner 305 to track my speed even on an indoor trainer?

tri-ac's picture
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tri-ac posted 1 year ago.

as long as it's on the wheel that's moving...

TriSooner's picture
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TriSooner posted 1 year ago.

Unless I am missing something, the Garmin tracks speed and distance by GPS. So if you are indoors on a stationary trainer, I think you'll be dissapointed by your results. But if you have a computer that measures speed and cadence by a magnetic sensor, then yes, you will get data if the mag and sensor are on the back wheel.

jellings9's picture
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jellings9 posted 1 year ago.

Garmin sells a speed/cadence add on kit for your bike which uses a magnetic sensor on your crank and rear wheel to measure speed and cadence. When you use that (which I do), it will calculate your speed using the RPMs of your rear wheel.

The first time it is used outdoors, the 305 will gather some data to enable it to calculate wheel speed into land speed. I guess it uses both the GPS and wheel RPMs untill it figures out the calculation.

Here's the add on:
https://buy.garmin.com/shop/shop.do?pID=1266

slammy's picture
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slammy posted 1 year ago.

that was the thingie I was I thinking about... so I just need to use it outside a couple of times before I can use it indoor...
Thanks

cjhoffmn's picture
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cjhoffmn posted 1 year ago.

Or you can set the calibration manually. I did that - its pretty easy to do.

Triguy98's picture
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Triguy98 posted 1 year ago.

Just remember that trainer speed is not close to road speed. The speed sensor is great for the cadence function, though.

Life is short. Play hard and get dirty doing it.

slammy's picture
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slammy posted 1 year ago.

just saw the two comments... I took a short ride outdoor one day to calibrate, and it seems to work pretty well.
Why is the speed on the trainer not close to the speed on the road? I thought that was the whole purpose of getting a fluid trainer, besides the fact it should be more quiet?
I've found one thing, on the few rides I have on the trainer so far, it's really hard - either because it's a trainer, or because I'm not in biking shape anymore :D

Triguy98's picture
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Triguy98 posted 1 year ago.

The resistance CAN be the same, or at least feel it to you when you get up to speed. But wheel speed and real speed/ resistance are different. I find that the trainer and rollers tend to give me a couple more mph "credit" than I get on the road.

Life is short. Play hard and get dirty doing it.