Need help understanding speedo and odometer
Help me out here. I have looked through some of the threads about the speedo healer and understand that I do need one. I need to understand how many miles I am getting out of a tank of gas after my sprocket change.
I am now running a 16 / 43 instead of the stock 16 / 41. I did find out that when my speedo reads 65 I am acually going 55. Is this consistant throughout the speedometer or does it change as speed decreases and increases? Also, I know my odometer is ticking faster now. How do I find out how many miles I am getting on a tank of gas? I appreciate the help because I am going on a long 3k mile trip and don't have time to order a speedo healer before hand. If I can just do a calculation that would be great. Thanks, Nick |
Originally Posted by Grasshopper
(Post 271941)
Help me out here. I have looked through some of the threads about the speedo healer and understand that I do need one. I need to understand how many miles I am getting out of a tank of gas after my sprocket change.
I am now running a 16 / 43 instead of the stock 16 / 41. I did find out that when my speedo reads 65 I am acually going 55. Is this consistant throughout the speedometer or does it change as speed decreases and increases? Also, I know my odometer is ticking faster now. How do I find out how many miles I am getting on a tank of gas? I appreciate the help because I am going on a long 3k mile trip and don't have time to order a speedo healer before hand. If I can just do a calculation that would be great. Thanks, Nick http://www.tweety.se/download.php?fi...aring VTR3.xls |
It's a percentage error, so it will change.
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Yeah... But with those sprockets the difference in total is 4.65% so a reasonable calculation would be 5% total to keep it simple... That's how much less you get out of your tank because of your change... That and some realworld test on your bike and you can figure out your tank range pretty accurately on the uncorrected number on your bike, ie when trip says X go fill up...
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The speedometer also comes stock with around a 5% error so your total error is -9.6%. I have the same 16x43 gearing as you and get an indicated 120 miles per tank exactly when riding in the mountains. So my actual range is right around 110 actual miles. I have started carrying an MSR fuel bottle under the seat as a reserve.
That got a little off track so to summarize, with your gearing you will be going about 10% slower than your speedometer indicates and racking up 10% more mileage on the odometer than you actually travel. |
u can fit something under the seat??????? lol i can get a glove in there if I'm lucky....
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Originally Posted by nothing
(Post 271965)
u can fit something under the seat??????? lol i can get a glove in there if I'm lucky....
The light stuff and the water bottles go to the outside of the subframe, the only thing to watch for is not blocking airflow to the R/R, so I often leave the right side empty, that'd free up a lot more room. And I did gain the use of most the battery box recently with my A123 batteries, so I now have even more room. But on to the question at hand. I am now running 16/43 and while the Speedohealer site said I should be at -9.6% I found that to actually get it correct (per GPS) I needed -13.3% However my rear tire is fairly worn now, and it might be a bit under inflated so that may be part of it. |
This is great info. I've been riding quite spirited lately and I'm getting an indicated 115 to 120 before reserve comes on. This thing swallows gas.
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Originally Posted by Grasshopper
(Post 271968)
This is great info. I've been riding quite spirited lately and I'm getting an indicated 115 to 120 before reserve comes on. This thing swallows gas.
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Ok, speaking of the 10% error. If I have an indicated 120 miles on my odometer do I multiply that by 0.10 to get the actual mile number?
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Then subtract 12 from 120 and that is my actual mile number of 108 correct?
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Originally Posted by Grasshopper
(Post 271941)
I did find out that when my speedo reads 65 I am acually going 55. Is this consistant throughout the speedometer or does it change as speed decreases and increases?
Thanks, Nick Cheers, Mike |
If you are off by -10% then: multiply by .90
or by .10 and subtract that from it. so 120 = 108mph |
Originally Posted by Grasshopper
(Post 271988)
Ok, speaking of the 10% error. If I have an indicated 120 miles on my odometer do I multiply that by 0.10 to get the actual mile number?
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So instead of multiplying by .10 multiply by .5?
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Originally Posted by Grasshopper
(Post 272006)
So instead of multiplying by .10 multiply by .5?
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Right, that's what I meant. Thanks for your help
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How is the odo off by 5% less than the speedo? I thought it got it's signal from the speedo sensor as well.
Lazn do you have a write up for your battery? |
Originally Posted by zwoehr
(Post 272020)
How is the odo off by 5% less than the speedo? I thought it got it's signal from the speedo sensor as well.
Lazn do you have a write up for your battery? |
Originally Posted by zwoehr
(Post 272020)
Lazn do you have a write up for your battery?
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