Speedometer accuracy?
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You've heard right, and it's pretty common with bikes in general, I believe. You can buy a device to "true" your speedo, but I just don't see the point.
I've always heard the 10% rule, so if I'm unless I'm on the interstate running at highway speeds, I just deduct 5 MPH or so.
I've always heard the 10% rule, so if I'm unless I'm on the interstate running at highway speeds, I just deduct 5 MPH or so.
Thanks. My last bike was pretty much on the money.
I kind of figured “50" felt a bit slow, and when I followed my wife recently, she appeared to do 55 in a 45-zone. I know she observes the posted limits, so figured my clock was off.
I kind of figured “50" felt a bit slow, and when I followed my wife recently, she appeared to do 55 in a 45-zone. I know she observes the posted limits, so figured my clock was off.
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55MPH on your speedo would really be about 49MPH. Where I live we have a bunch of those signs that display your actual speed. I check it all the time. When my speedo says 50, it's really 45. This holds true for my 2005 C50T when I had it, as well as my 2007 Nomad. However, the odometer is fairly accurate. Go figure.
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Yep....Mine is off 4 to 5 mph until I hit about 60 and then it's off 6 mph...I just know the speedo reads 5 mph more than actual speed and I'm ok with it.notmycity said:
I always used to give my husband hell if he was leading telling him I wasn't going to pay for a speeding ticket. He swore to me he wasn't speeding so I figured mine must be off a bit.
I had my husband wire the new GPS. On my first ride around my speedo is exactly 9 kms off (which would be about 5 miles).
I had my husband wire the new GPS. On my first ride around my speedo is exactly 9 kms off (which would be about 5 miles).
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285 Posts
Aerostich <www.aerostich.com> offers a Sigma bicycle speedometer/clock/stopwatch/etc. for about $40 including S & H. Check out their web site and thpe in "Sigma" in the search window after it loads.
It's fairly easy to mount on the handlebar and the sensor unit can be attached inside the right side front fork with expoxy with the connecting wire wrapped around the brake line leading up to the handlebar. lYou'll need to supply a strong magnet, which is easily attached to the front brake rotor with some expoxy in alignment with the sensor. I found some Neodymium magnets that were cheap and readily available at the local hardware store, about dime sized, but a bit thicker.
Calibration is done with the unit head (detachable) as that's where the battery is. You need to know the front tire circumference and be able to convert it to millimeters (25.4mm/inch).
The battery should last several years, the accuracy is related to how careful you calibrate it and it's a godsend to know exactly how fast AND how far you've really gone. Mine is ccurate to within 0.2 miles in 500 mi. and the speedo shows that at 60 and 72 MPH it's right on with them taking exactly 60 seconds or 50 seconds respectively, going down the freeway with mileage markers as a guide.
This accessory allows you to see the error of the bike's speedometer without modifying the circuit with a "corrector" or yellow box as they're affectionally known around here. It's cheaper too.
Ray Nielsen, in Minneapolis and finally riding aftera long winter.
It's fairly easy to mount on the handlebar and the sensor unit can be attached inside the right side front fork with expoxy with the connecting wire wrapped around the brake line leading up to the handlebar. lYou'll need to supply a strong magnet, which is easily attached to the front brake rotor with some expoxy in alignment with the sensor. I found some Neodymium magnets that were cheap and readily available at the local hardware store, about dime sized, but a bit thicker.
Calibration is done with the unit head (detachable) as that's where the battery is. You need to know the front tire circumference and be able to convert it to millimeters (25.4mm/inch).
The battery should last several years, the accuracy is related to how careful you calibrate it and it's a godsend to know exactly how fast AND how far you've really gone. Mine is ccurate to within 0.2 miles in 500 mi. and the speedo shows that at 60 and 72 MPH it's right on with them taking exactly 60 seconds or 50 seconds respectively, going down the freeway with mileage markers as a guide.
This accessory allows you to see the error of the bike's speedometer without modifying the circuit with a "corrector" or yellow box as they're affectionally known around here. It's cheaper too.
Ray Nielsen, in Minneapolis and finally riding aftera long winter.
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We're supposed to look at the speedometer? What happened to 'slightly faster than average traffic'?
Seriously, I just assume about a 10% error rate and try to stay within 5MPH over the assumed error which usually works out to a little faster than most traffic. I'd rather react to what's ahead of me than try avoiding what's behind and catching me.
Seriously, I just assume about a 10% error rate and try to stay within 5MPH over the assumed error which usually works out to a little faster than most traffic. I'd rather react to what's ahead of me than try avoiding what's behind and catching me.
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Speedometer
Per my Garmin GPS about 10% on the low side like others are saying here.
Per my Garmin GPS about 10% on the low side like others are saying here.
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675 Posts
Re: Speedometer
The GPS has a little lag time in it so you have to get cruising at a steady speed based on the GPS for a few moments and then look at the speedo, you'll probably find it to be closer to 15%. At low speeds it may only be 1/2 MPH or less so not very noticible but at 50MPH or above you'll see the greater error.
I thought it was 10% too bsed on my GPS until I redid my facpalte and then found it was still off by a couple of MPH. It really is between 14% and 15%.misguidedute said:
The GPS has a little lag time in it so you have to get cruising at a steady speed based on the GPS for a few moments and then look at the speedo, you'll probably find it to be closer to 15%. At low speeds it may only be 1/2 MPH or less so not very noticible but at 50MPH or above you'll see the greater error.
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1,331 Posts
Did the GPS thing on mine and as stated here it's off by 10%. Easy to figure without spending much money on corrective devices.
Just subtract 10% off what the speedo is showing. (If your showing 60mph - your actual speed is 54mph)
Or go 10% over what the speedo shows for the desired speed. (If you want to travel 60mph - go 66mph on your speedo)
Just subtract 10% off what the speedo is showing. (If your showing 60mph - your actual speed is 54mph)
Or go 10% over what the speedo shows for the desired speed. (If you want to travel 60mph - go 66mph on your speedo)
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1,659 Posts
the following words, do not and never will go together.....
motorcycle..... speedometer... accurate.....
They are allowed about 12% discrepancy by Fedl guidelines.
I did the speed-o-healer on my Kaw Classic, and just do the 10% thing on the Volusia. I was not going to try to remember how much each bike was off.....
motorcycle..... speedometer... accurate.....
They are allowed about 12% discrepancy by Fedl guidelines.
I did the speed-o-healer on my Kaw Classic, and just do the 10% thing on the Volusia. I was not going to try to remember how much each bike was off.....
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Just got the Ram mount in for my Garmin Nuvi 760 - tested the accuracy of my C90 speedo yesterday... here is what it looks like:
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This mount will adjust / tilt in various directions (you don't have to have it "upright" like the way it is pictured)... I mounted it on the bars between the risers.
The speed indicated on my C90 was @ only 5 miles off between 45 - 75 indicated...
Here's a small charting of what I found:
at 76 mph indicated, I was actually doing 70 mph...
75 mph indicated = 69 mph actual
70 mph indicated = 65 mph actual
65 mph indicated = 60 mph actual
60 mph indicated = 55 mph actual
55 mph indicated = 50 mph actual
50 mph indicated = 46 mph actual
45 mph indicated = 41 mph actual
40 mph indicated = 36 mph actual
35 mph indicated = 32 mph actual
This mount will adjust / tilt in various directions (you don't have to have it "upright" like the way it is pictured)... I mounted it on the bars between the risers.
The speed indicated on my C90 was @ only 5 miles off between 45 - 75 indicated...
Here's a small charting of what I found:
at 76 mph indicated, I was actually doing 70 mph...
75 mph indicated = 69 mph actual
70 mph indicated = 65 mph actual
65 mph indicated = 60 mph actual
60 mph indicated = 55 mph actual
55 mph indicated = 50 mph actual
50 mph indicated = 46 mph actual
45 mph indicated = 41 mph actual
40 mph indicated = 36 mph actual
35 mph indicated = 32 mph actual
I know they are off somewhere around 10% or so and read slow but never lost any sleep over it. I just consider it a safety feature that keeps me from getting too many speeding tickets around town. On the highway I ride where I'm comfortable and with the flow of traffic or maybe slower (depending). I pretty much ride where I'm comfortable based on road conditions and traffic regardless of what the speedo says.
Cheers!
Cheers!
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24 Posts
I finally got a phone mount on my C50 and ran GPS Speedometer and found that 71 on the dial is where I need to be to actually go 65mph that most of the interstate roads are in Kentucky. So when I am on the backroads thinking I am doing 45 and cars are stacking up behind me acting all impatient...I now know why! It looks like I am riding like a grandpa out there. Oh yeah...I am a grandpa! lol
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