Indicated vs Actual Speed

[mimico_polak]

Hey guys,
Hope you all had a good weekend of riding!!!! I took the trip to Collingwood up 27 from Toronto, and then Airport Rd. down to Mayfield and the 410 the rest of the way to Oakville...awesome awesome awesome! I enjoy putting around town during the week back and forth from work and regular commuter things...but this ride just made enjoy the bike more than I expected! There were a ton of riders on Airport Rd and it was good to enjoy the weather!

Now to the topic...I put my GPS into my tank bag (through the plastic film) in order to see how effective it is...not bad but need to take my eyes off the road for a few seconds to see what's going on and when/where to turn...but when I turned on the gps to show speed...there actual speed was about 8-12% lower than indicated. Could be the GPS so I'd need to try another one to confirm, but is this normal for bikes? Any fix for this? Or just do the math in your head each time? IE: 100kph indicated was 90-92kph GPS.

[tricky]

most bikes are off at that speed, I know it's normal for my bike to be off by about 15% at the higher end. I just judge my speed by what everyone else is doing

I think I saw TAFB post something recently about a speedo doctor for FI bikes

EDIT: here's the thread: http://www.gtamotorcycle.com/vbforum...ny-suggestions

[KC_VTX]

I have the exact same thing on my bike. It is consistent at 10%. 50 on speedo - 45 on gps, 130 on speedo - 117 on gps. I just do the calculation and ride accordingly.

[viper84737]

I've long since stopped looking at my speedometer because of this ridiculousness. GPS for me.

[IXFe]

...I put my GPS into my tank bag (through the plastic film) in order to see how effective it is...not bad but need to take my eyes off the road for a few seconds to see what's going on and when/where to turn...but when I turned on the gps to show speed...there actual speed was about 8-12% lower than indicated. Could be the GPS so I'd need to try another one to confirm, but is this normal for bikes? Any fix for this? Or just do the math in your head each time? IE: 100kph indicated was 90-92kph GPS.

get thee a RAM Mount.
yes. many bikes I've seen display a velocity +10% higher than actual.. verified against GPS or those "YOUR SPEED IS ____ km/h" informational electronic signs popping up all over the land.

[jeffjones]

The manufacturer is allowed a +/-10% on the speedometer's calibration.
Once you get into changing gearing that number can jump very high from being correct.

[mimico_polak]

Thanks for the responses guys. I think simply due to $ I'll just do the math while riding! LoL
IXFe thanks for the suggestion...I'm looking into the mounts at lunch and it looks like a great option instead of looking all the way down to see the GPS.

[kamikaze]

if you're looking at RAM mounts and aren't in a big rush, order them from gpscity.com instead of .ca

it'll ship from the states USPS, but the shipping charges are waaay lower. If you need it asap, the .ca site ships pretty quick, downside is the cost. I needed a small part that was around 8 bucks, and the shipping from .ca was 10. had it shipped from the .com and it was .99 to ship and I got it in a couple weeks.

[Emerald94]

Radioworld carries RAM as well:
www.radioworld.ca

if you're looking at RAM mounts and aren't in a big rush, order them from gpscity.com instead of .ca

it'll ship from the states USPS, but the shipping charges are waaay lower. If you need it asap, the .ca site ships pretty quick, downside is the cost. I needed a small part that was around 8 bucks, and the shipping from .ca was 10. had it shipped from the .com and it was .99 to ship and I got it in a couple weeks.

[gjones4487]

I had the same problem, i had a gear change -1f/+1r and it was off by 12%. I purchased a Speedo DRD, very easy to calibrate, very compact (about the size of a quarter) and it is also affordable. and if you go to the states for an extended period of time you can switch the display to MPH from KPH.

http://www.speedodrd.com/

[2live&ride]

+1 on the SpeedoDRD

Two plugs and one button to program.
I had Johnny install new a chain/sprockets yesterday (-1/+2) and took him a few minutes to program the speedo drd.
Works Great.

[alhope34]

My bike has OEM sprockets and at 128 km/h indicated it is 120 km/h actual speed.

[kiwi]

note, some bikes like the BMWs show accurate speeds.

[Spiider]

Honda cars just went through a big class action lawsuit over this...they were only off by 3% or so.
Now that GPS are cheap to have everyone knows how inaccurate their speedos are.

Don't forget, your vehicles warranty is also up 10% faster than it should be as well.

Honda had to reimburse for repairs that happened just after the warranty expired...if you incurred costs etc.