GPS instead of speedo/odometer [Archive]

JerryAttrick

01-17-2009, 11:28 AM

r11rs94

01-17-2009, 12:40 PM

My R1150RT has a 15" front wheel due to the sidecar conversion. This gives me a big error in speed and distance. (Indicated 60 mph = 50 actual) I am looking into ways to deal with this.
Would a GPS be a viable substitute for both functions?
Thanks for your input,

When I'm using my GPS I have it set up so its in my line of sight. I hardly use my speed-o at all when using the GPS.

PGlaves

01-17-2009, 12:43 PM

My R1150RT has a 15" front wheel due to the sidecar conversion. This gives me a big error in speed and distance. (Indicated 60 mph = 50 actual) I am looking into ways to deal with this.
Would a GPS be a viable substitute for both functions?
Thanks for your input,

A GPS will tell you both speed and elapsed miles. Elapsed miles since you reset it. I use mine as a trip odometer all the time. Or it can be reset like a trip meter to keep track of fuel fill-ups.

Depending on how innacurate your OEM odometer is you might have to check the "don't know" box on the milege form if you ever sell the rig.

papagian

01-17-2009, 03:44 PM

My speedometer is off by 4 mph, reads 60 when actually travelling at 56. The GPS unit is more accurate, it is off by 1 mph. It reads 60 when travelling at 59 mph. Why a German-built machine should have anything less than an uber-accurate (no folks, German is not my native tongue) speedometer has spawned at least a few theories. The GPS is definitely the more accurate instrument (especially for in your case, Mr. JerryAttrick.)

kgadley01

01-17-2009, 04:00 PM

My speedo on my RT is off also. It drives me nuts always trying to figger out how fast I'm going. I've done some research and have decided to buy the Garmin Zumo 450, and mount it on my accessory shelf directly in line with my sight. the reason I picked the 450 over the 550 is the 550 has a bunch of extras I would never use. My main reason for buying the GPS is for Speedometer function. I'm sure as I get used to it I will also use it for other things. :thumb

tommcgee

01-17-2009, 05:52 PM

I never look at the speedo on the bike -- always use the Zumo.

JerryAttrick

01-18-2009, 08:30 AM

Looks like the Zumo (or equivalent) is the way to go.
The existing odometer can still be used for overall milage by multiplying by the fudge factor - to keep the maintenance schedule accurate. (I wouldn't want to push the wrong button some day and erase the total.) What I need is a accurate real-time indication of speed, because there are local officials that don't feel the decision is entirely my own.
Of course, once I get it on a long trip, the nav feature will be very handy.
Thanks for the info,

BubbaZanetti

01-18-2009, 11:23 AM

i think with my next bike i may actually redesign the instrument cluster to have only a tach and a sorta bathtub like insert for the gps.

bdiver

01-19-2009, 08:32 AM

May of us on the SABMAG (Sabre Magna) list have used Sigma bicycle computers for years. I have the BC800 which has probably been replaced by now with a newer model but they go well into the triple digits (so I'm told:thumb ) and give you a trip meter, odometer, top speed, clock and all sorts of good info. Inexpensive and accurate. Something to think about!

amiles

01-19-2009, 09:50 AM

It seems as though lots of folks take the speed indicated by their GPS as gospel. I'm not saying that it isn't but I wonder where the truth lies?

In particular I wonder how quickly the GPS updates the display as speed changes?

Are the newer units with the faster processors better at this than their older relatives?

BubbaZanetti

01-19-2009, 10:14 AM

prhkgh

01-19-2009, 10:33 AM

I wrestled with similar concerns with an old URAL bike/sidecar I had. Not only was the speedo/odometer in kilometers rather than miles, but the needle of the speedometer was missing when I got the bike. So I had no idea of real speed, and had to multiply the odometer to get miles (if I cared.)

I went to a local bicycle shop and bought a bike "computer'...cost me about $35. I made a mark on pavement and pushed bike one full wheel revolution so I got true rolling circumference measurement, so I could program the bike speedo. figured out how to mount sensor and magnet to wheel and strut so it would read the pulses, and went on my way.

Worked GREAT! didn't take up much space, gave me mph and miles, also gave me various trip computer functions (avg speed, etc.).

Overall was a simpler solution than a GPS, besides taking up less space and power.

HTH

Paul

kgadley01

01-20-2009, 06:12 PM

I ordered my new Zumo 450 today...:dance

tommcgee

01-20-2009, 08:01 PM

It seems as though lots of folks take the speed indicated by their GPS as gospel. I'm not saying that it isn't but I wonder where the truth lies?

My Zumo tells me exactly the same thing as what the Maine State Police tell me when I get bagged on the turnpike. :nono

kgadley01

01-21-2009, 02:27 PM

My Zumo 450 came today... less than 22 hrs from purchase to delivery. now thats fast. I've already got it installed, so if it would just warm up a bit..........

adooley

01-22-2009, 09:02 AM

On my 1150RTP, it has a police speedo that is supposedly accurate to + or - 1mph. I have tested that with my Garmin 478 and found it be true up to 90mph (As fast as I am willing to go unless being pursued by the ex). Unfortunately, the police speedo is about $188, new. It also wouldn't be applicable in the situation of a rim size change from 17" to 15". I wonder if it is possible to crack open the speedo and change the gears to match the new wheel size? I think there used to be way to that for cars? Just my one-cents worth (due to the economic situation, I can't afford the additional cent). :type

kgadley01

01-22-2009, 09:25 AM

I don't think thats something you want to attempt yourself, but I believe there are companys out there that can...

dnixon

01-22-2009, 09:45 AM

My Zumo 450 came today... less than 22 hrs from purchase to delivery. now thats fast. I've already got it installed, so if it would just warm up a bit..........

I've been using my StreetPilot 2730 every morning for XM goodness. Temps have been in the low as 20's and high teens. <Bike wouln't start at 8 degrees, grrr>

There is a little condensation on the screen after a bit and when it's really cold, the screen refreshes very slow. However, thus far no problems other than a need for new and warmer gloves.

stkmkt1

01-22-2009, 11:31 PM

Since it is #$%^& winter here in Central Illinois, I have my Zumo 550 in my Avalanche. I have found that I seem to watch my speed on the Zumo more than the speedometer. They do seem to read the same though so I suppose it does not matter. Got the XM antenna mounted on teh bike. Now all I need is to get the snow off the roads and time to go for a ride.

DPeakMD

01-23-2009, 07:37 AM

My Garmin 2720 screen will slow down and eventually fade to black after about 2-3 hours at speed in 20'ish degree weather. It's slightly exposed to the air currents under the windshield on my RT.

Once it warms up, it's good to go again. No lasting effects, but while it's blacked out it's pretty much useless as a display. It is still working, though. So you can get turn-by-turn and track log!

I wonder if the Zumo series is more robust since it was purpose-built for m'cycle use.

kgadley01

01-23-2009, 09:45 AM

dnixon

01-23-2009, 11:30 AM

They claim that the Zumo series is all weather proof, I guess we'll see...

According to the Zumo Owner's Manual, the "Temperature range: 32F to 140F".

JanMiller

01-23-2009, 02:07 PM

When I'm using my GPS I have it set up so its in my line of sight. I hardly use my speed-o at all when using the GPS.

Ditto. I seldom look at the speedo when the GPS is mounted...

kgadley01

01-23-2009, 07:42 PM

According to the Zumo Owner's Manual, the "Temperature range: 32F to 140F".

could be, I haven't read, or even opened my manual yet. I'm one of those guys that will try to fix or build anything. If all else fails,I will get the instructions or manual out.... :thumb

Cruzin

01-25-2009, 02:58 AM

I also use the Zumo 450 and find it more accurate than the speedo. My speedometer always tells me that I'm going faster than I really am. I guess it has a lot to do with tire wear, as a speedo is dirrectly related to tire circumference. And I know my tires wear down fast due to the small surface area wearing on the road when travelling straight.
I have cross referenced my Zumo with both of my Toyotas and found it to be almost exaclty the same as both cars speedometers.

Motowalt

01-25-2009, 06:09 AM

Can the 1150GS speedo be corrected by changing the drive gear at the front wheel to a different part number ? :scratch

I run a Zumo, but it just bugs me that the OEM speedo is off...

PETDOC

01-25-2009, 07:58 AM

Can the 1150GS speedo be corrected by changing the drive gear at the front wheel to a different part number ? :scratch

I run a Zumo, but it just bugs me that the OEM speedo is off...
Yes. I have an '04 GS which came with a speedometer indicating 10% greater mph than my Zumo. For about $35 I bought a different ratio speedo hub, changed them out in 5 minutes and now speedometer is about 2% fast. You can get part number for the speedo hub by going to advrider.com and doing a search on the topic. Although I use my Zumo for speed measurement, it is not always on my bike, so I really appreciate having a more realistic reading from my speedometer--especially when I blow past a police man with a radar pointed my way.

Polarbear

01-25-2009, 08:37 AM

My older R100/7 and its antiquainted speedo/tach was never a jewel to rely on and I finally got tired of rebuilding it, so I took them off and they stayed off the bike permanently:). Today the GPS Garmin76CS is in place and works perfectly. No tach however, but think about, do you need one? I don't on the old bike. Randy:usa

kgadley01

01-25-2009, 03:36 PM

Can the 1150GS speedo be corrected by changing the drive gear at the front wheel to a different part number ? :scratch

I run a Zumo, but it just bugs me that the OEM speedo is off...

You can use any Police model speedo and it will be accurate. I believe they make the big GS in a police model.

JerryAttrick

01-25-2009, 04:33 PM

Yes. I have an '04 GS which came with a speedometer indicating 10% greater mph than my Zumo. For about $35 I bought a different ratio speedo hub, changed them out in 5 minutes and now speedometer is about 2% fast. You can get part number for the speedo hub by going to advrider.com and doing a search on the topic. Although I use my Zumo for speed measurement, it is not always on my bike, so I really appreciate having a more realistic reading from my speedometer--especially when I blow past a police man with a radar pointed my way.

I would love to know more about those different ratio speedo hubs, but I could not find anything on advrider. Do you know who sells them?
Thanks,

atlbmw

01-27-2009, 01:24 AM

... just a tach for me
I just kind of estimate my speed....based on rpm's and my gear....

I guess it might get me in some trouble on some backroads, but I've been lucky so far. I guess i'll fix the speedo eventually... :dunno

peace

RedRam

01-27-2009, 08:43 AM

Good comparison info on GPS's can be found at gpsmagazine.com/ . I keep reading about how wildly inaccurate beemer's speedos are, but I haven't found that to be the case. Of course, I'm limited to only checking my two beemers: '96 r1100rs, & '97 F650st. I checked the speedos against my Garmin Nuvi, as well as my jeep and Dodge truck, (at different speeds), and IF the gps is correct, then all are consistant @ 2.5-3 mph under actual speed, and the odo's on all are exactly on. But- I don't know how accurate the gps is, at least it's consistant:thumb

JerryAttrick

01-30-2009, 06:36 AM

OK. Here is the wrap-up.
I'd love to have GPS on both bikes and the truck, but that's $$$.
I don't want anything I have to remember to remove every time I get off it.
The security boxes are ugly, and I don't like leaving expensive electronics out in the weather.
The existing odometer is off, but by a known multiplier, so it is easy to figure the actual milage at any time - for maintenance intervals.
The bicycle speedos are great for the speed reading, but have the problem that any button-pushing bozo walking by could mess up milage history.
Conclusions:
1 Get a bicycle speedo ($20) for the sidecar rig, mount it "permanently", and use only the speed readout, and the ocasional trip milage. (If it gets stolen or takes on water - it's easily replaced.)
2 Use the stock odometer, multiplied by 5/6 fudge factor, for maintenance intervals.
3 Get one Zumo for use in any vehicle, but only when the trip merits it.
And that, gentlemen, wraps it!
Thank you all for the very useful input.