GPS to replace speedo?

I have a couple of questions for anyone who has a gps as there speedo? yesterday i bought a garmin 315 and i thought of just using it for navigation. the speedo function looks like it would work well enough to remove my old 87 xr600 digital unit. But i don't know how it will stand up to bad weather like cloud cover. and my other question is if i buy the power cord so i don't need to run AA batteries will i have to convert to D.C. power. i am street legal and run even my L.E.D. signals on A.C. the only thing i don't have is a flasher because for that i need a battery and i really don't want to have to back a battery with me. also want to know if anyone else has used this garmin 315 and how it stands up to bike riding?

Thanx :banghead::banghead:

i got a garmin e-trex cheapest gps i know of. its been on both my bikes around 14,000 miles combined.stays on the the bike all the time.I did go to wal-mart picked up a $8. 12volt waterproof outlet bought a cord for the gps off e-bay for like $10. the cord conveted the power from 12volt to 2volts.the cord died on my last trip had to go back to batt. for now. cord did last 2 years not bad i guess.the gps has worked fine 98% of the time & the speedo is probally more accurate then my speedometer.

I have a Garmin eTrex mounted on my XR600. Its great. It would work fine as a replacement for the speedometer, but I would not use it to replace my odometer. The GPS just isn't as reliable as the odometer. For example, if you are riding thru the trees sometimes your GPS won't pick up a good signal and it will be off. I use an external battery for the eTrex to minimize the chances of losing power. I think the digital speedometer/odometer on your year XR is a trick setup. Keep it and use the GPS for navigation.

P.S. I have used my GPS as a backup odometer on a Dual Sport ride once. My mechanical odo cable broke.

Just my 2 cents.


if you are riding thru the trees and loss the signal the gps will correct itself when it picks up the signal again.

if you are riding thru the trees and loss the signal the gps will correct itself when it picks up the signal again.

Thats right, the speedometer function would work again as soon as the signal is back. But the GPS odometer function could be off depending on for how long the signal was lost. Maybe he doesn't care about the odometer function and in that case he could just use the GPS. But if he plans on doing a organized dual sport rides in the future (where you rely on the accuracy of the odometer to navigate), then it would matter.

the odo corrects itself

I use a RINO 120, and it's cool to have a digital speedo read out. The RINO, and many other Garmin units are very waterproof.

Here's the deal with power:

If you run off the batteries, the vibration will destroy the contacts, and unit will quit. And if you run at night the batteries will be shot real quick if you run the backlight.

If you use the power from the bike, it has to be DC, and should be "clean" DC, not the choppy type you find on a motorcycle.

If you don't have an E-start bike, you have AC for 12v power, and that won't do for your GPS power.

I'll try to remember and post the website that sells a 12 AC to clean 12 DC converter for powering up GPS units.

This unit should be hard wired, not a cig. lighter type adapter.

This one of my next mods to my bike...

Found it!

Take your time and read up on tips for your motorcyle...

thanx alot for the info! i think i will just keep it in my pocket now

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now