GPS Speedo?

[Yarr]

I have my road test coming up in a month and by taking my phone to my tank I found that my speed is 10% lower than the reading, and the dominant scale is mph where I need it to be kph (brain doesn't do the conversion fast enough lol)

Wondering if anyone has tried out one of these GPS-based speedometers they have on Amazon etc? The ones that would drop in where the current one is. Wondering what your thoughts are.. ones like this:

https://www.amazon.ca/Waterproof-Spe...fsL&ref=plSrch


Or if you've ever replaced one for that matter know what the distance is between mounting bolts on the bottom? Or where to find out..

[Triple Jim]

I know guys with GPS speedometers and they're OK. Accurate most of the time, but have a lag when starting out, and can lose the reading if you're riding down a road with a lot of trees, for example. I've decided that any of the electronic ones that let you calibrate them are better for my use. You put a magnet on a wheel or rear sprocket, and a sensor to pick up the magnet pulses, and you enter the distance traveled per pulse.

Now for boats it's hard to beat the GPS type.

[DannoXYZ]

Factory speedo is mechanical with gears and cables. There's a finite amount of gear ratios from hub through speedo-drive and engineers end up with selecting an optimistic combination rather than risk people speeding inadvertently.

Yeah, GPS has slight delay when speed and position changes. If you're going at steady-speed on freeway for several minutes, it'll report accurate speed. But if you do lots of braking in stop & go traffic, it won't be accurate.

I use one of these digital Trailtech Vapor gauges. You calibrate it by measuring roll-out distance of front-tyre and plug that into unit. Then it does all the calculations based up on time-interval between each wheel-rotation to arrive at speed, very accurate. I fine-tune the setting using stopwatch and mile-markers on freeway as well as with GPS and it's spot-on to 0.1 kph. I also like having 24-hr clock and actual coolant-temp readouts (in F or C). Stores maximum speed and temps for later recall. Programmable RPM shift-light.

[Alex]

Originally Posted by DannoXYZ

Yeah, GPS has slight delay when speed and position changes. If you're going at steady-speed on freeway for several minutes, it'll report accurate speed. But if you do lots of braking in stop & go traffic, it won't be accurate.

I don't see this behavior on any of my GPS units on bikes. Delay, if any, is sub-second. GPS units don't calculate velocity only by figuring out where they are, figuring out where they were, and doing the math. If that was the only method - it would be subject to much more variability. GPS chips use the radio signals, and the change in those radio signals, as another method to measure velocity directly, as well as using position change as another input to continuously re-calibrate. Heck - turn location on for any modern smartphone, make sure it's set to high accuracy (an option on some Android phones to use full GPS or just the A-GPS), and mount it on a tankbag or a bar mount with a GPS details app running, and watch its behavior.

All that said, I can't confirm that the GPS chips put into a knock-off gauge cluster will be awesome, OK, or 15 year old tech that might have issues. But my hunch is it would be harder to buy one now that works (but works badly), as even the best GPS chipsets are dirt-cheap in 2018.

[Yarr]

Hey guys thanks for the responses! I've been looking at options since I posted including the Trailtech Vapor and it looks like that may be the route to go, despite it seeming like a solid day or so realistically required to get that mounted and wired up. The instrument cluster on the 07 looks like it might be one piece and hence not just replaceable with a single-instrument drop-in. I just know from personal experience that anytime a mod is required I need to add at least a day to fiddling and fitting etc

[MrAtom]

Yeah, the cluster on the 07 is indeed one piece. It has a trim piece:



The cluster:



And the gauges that come out like this:



While I don't think it'd be impossible to replace JUST the speedo, I don't think it'd be worth your while.

[Djdougb]

I’ve got one of those Speedos from the amazon link on my bike and it works great. Only con is it can take a minute to find satellites to link up to. Not sure about the mounting as I made a bracket for mine and put it right on the triple clamp.