Computing ride official ride distance

BMW RT Pilot

Premier Member
#1
Over the course of my (brief) IB career, I've found that my GPS and bike odometer were pretty much in sync in terms of distance traveled, with the GPS reading about 16 miles higher. Since I typically ride about 100 miles more than the required distance on any given ride, this was never an issue.

On my last ride, a SS2K Gold, I wasn't planning on riding that much extra, and while the GPS was reading well OVER 2,000 miles, the odometer was about 60 miles UNDER! I ended up riding a lot more to make sure the bike's odometer went over 2,000 miles.

Both Google Maps and Garmin Basecamp showed that the ride was going to go well over 2,000 miles, pretty much matching what the GPS was saying. So my question is: Which reading is more aligned with what the verifiers use when verifying these rides?

For those asking how/why I am seeing this wide gap in readings, it's because I went Dark Side. I know it's affected the speedometer so it follows that the odometer would also be affected.
 
Last edited:

Ira

Staff member
Premier Member
IBA Member
IBR Finisher
IBR Staff
#2
Odometers are notoriously wrong. A good rule of thumb is to plan a route that is at least 2-3% longer than the calculated minimum distance.

Ira Agins
Iron Butt Association
 

kwthom

=o&o>
Premier Member
IBA Member
#4
<...>For those asking how/why I am seeing this wide gap in readings, it's because I went Dark Side. I know it's affected the speedometer so it follows that the odometer would also be affected.
Bad enough for Honda that they lost a class-action lawsuit several years ago over this issue:

https://www.autoblog.com/2007/02/19/odo-uh-oh-honda-extending-warranties-on-6-million-cars/

On my 2016, the speedometer is within 1MPH; the odometer is around 3% optimistic with a Dark Side tire installed.

For those reading along, you may actually want to measure the error, just so you know the amount of error you're experiencing.

Ride 50 or 100 GPS miles/km, note the delta between your GPS (or your cell phone GPS) and your odometer.

Then, you'll know!
 

BMW RT Pilot

Premier Member
#5
Bad enough for Honda that they lost a class-action lawsuit several years ago over this issue:

https://www.autoblog.com/2007/02/19/odo-uh-oh-honda-extending-warranties-on-6-million-cars/

On my 2016, the speedometer is within 1MPH; the odometer is around 3% optimistic with a Dark Side tire installed.

For those reading along, you may actually want to measure the error, just so you know the amount of error you're experiencing.

Ride 50 or 100 GPS miles/km, note the delta between your GPS (or your cell phone GPS) and your odometer.

Then, you'll know!

Crazy stuff. I need to find one of those setups the cops put out telling drivers what their speed is. Would hate to get a "letter of achievement" from a trooper. LOL

Weird, the section that I bolded isn't in the original reply, but yeah, I am seeing a 60 mile difference, as stated.

Edit: Well wait- it looks like the info was added while I was replying.
 

Stephen!

Flivver Flyer
Premier Member
IBA Member
IBR Finisher
#6
The curvier the roads, the more to the "less than actual" side of the error will be the GPS. Depending on the refresh rate of the GPS (the 276/376/478 style Garmins is 1 Hz, for example) and the timing of the refresh through the corners, it could add up quite significantly.