Garmins - Speed

Let me ask a dump question. Do the Garmins measure speed while riding without having a sensor? Sorry this may sound like a very stupid question but I am still used to regular cycle computers with magnets. I also dont get why Garmin offers a speed sensor or is that simply for riding on a trainer?

Yep they can. The speed sensor provides a more accurate way of measuring, which is cross-referenced with the GPS

The Garmin chainstay unit is also a combined speed & cadence sensor - reads a spoke magnet and a magnet on your crank arm.

Thanks guys! Thats all I wanted to know.

And AFAIK, if the sensor is fitted the Garmin will use that exclusively for speed. Otherwise it uses GPS.

It even auto calibrates the wheel size for the speed sensor using the gps for you, pretty cool!

You can also enter it manually, IIRC

i was told by a friend that works in a LBS that the magnetic cycle computers get a bit screwy when you walk out of the store past the security bollards. not sure if he was pulling my leg put I found it a possibility.

And if you are using a powertap it will use some funky arithmetic to get cadence without the sensor

I figured that all I really want are maps, my current position and upload my routes. Does someone ever use one of the eTrex Garmins?

Dirt rides often leave me without reception and wandering where I actually am or where to go. One of these handhelds would solve this issue or am I thinking something wrong here?

quite a number of my friends who are prone to long rides in the bush are fans of these. and i mean spontaneous multi-hundred km ‘day trips’.

yep, I have an older etrex 60csx, but when that dies I’ll be getting an etrex 20/30. Full maps with topo’s, AA batteries can USB power off a dynamo, I leave mine in the frame bag/pocket unless I need to check something.

The 60csx is more of a outdoorsy GPS, completely waterproof, really good reception under canopy, fast satellite pickup and very accurate just overkill and bulky for cycling.

However, if your looking for a quick and free solution, get the Openstreet map app for andriod, download maps, turn phone GPS on and your away.

I quite like mine - I’m no multi-hundred day tripper. But am quite good at getting myself well lost in the bush. Open Street and Cycle maps, do not pay for garmin maps… Mixed with to plan your route.