Speedometer Error - Suzuki GSXS1000 Forum
User Tag List

 15Likes
Reply
 
LinkBack Thread Tools
post #1 of 63 Old 04-27-2016, 03:19 PM Thread Starter
Senior Member
 
USSENTERNCC1701E's Avatar
 
Join Date: Apr 2016
Location: Utah, USA
Posts: 529
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 164 Post(s)
Garage
(Thread Starter)
Instructions in post #37

BLUF: 6.7% Speedometer overread on 2016 GSX-S1000F, US model.

Not yet familiar enough with the forum to know if this is the best place for it, if not, sorry.

I'm planning to install a Speedohealer. I don't like speeding for my commute, but here in Utah, it's dangerous to drive below the speedlimit, especially on a sportbike; seems to be people expect you to be speeding and if you're not, don't expect even a modicum of respect for your personal safety. Friday I got passed (on a four lane road mind you, with me in the right track of the right lane) so close I could have reached out and touched the car. And in my experience here, even if there's a cager near by going faster, it's the biker that'll get pulled over. So, I'd like to be able to know how fast I'm actually going.

For now, I'm calculating the percent error. I took my phone and a GPS logging app for a ride, about 20 minutes sustained at 60 MPH indicated. I trimmed off the initial acceleration and deceleration data, then deleted obvious outliers with data in chronological order. Next I reordered the data ascending with measured speed. I used a linear fit, and trimmed the leading and trailing data until the R-squared value was over 0.99 I then switched back to chronological and the linear fit had a slope of .0001 I considered this sufficient. All told I had 832 remaining data points for 20 minutes at sustained speed. My standard deviation is 0.44 MPH, given the speedometer readout is to the nearest whole MPH, this is within the instrument error. I got 55.97MPH actual for 60 indicated, a 6.71% overread, calculated by ( actual/indicated 1 ) x 100

For 75 indicated, after analysis, got 70.00 actual, standard deviation 0.34, slope of linear fit for chronological order -0.00005, R-squared for linear fit on ascending order 0.9948, but only 437 data points and 12 minutes. Total overread, 6.67%. So still rounds to 6.7%, and the speedohealer only increments by 0.1%.

I got a handle bar mount for my phone, and put the GPS app in speedometer mode. With 6.7%, some speeds I took a look at, expected Actual/Indicated: 14.00/15; 27.99/30; 41.99/45. It's hard to hold this bike at 15MPH, but the other two checked out just fine, rounded to the nearest whole. Further, drove past a speed limit sign with integrated radar and readout, sign said 28, bike said 30.

Overall, seems the speedometer error is linear, 6.7%. I've got a speedohealer in the mail, should show up today. I haven't been able to find anyone claiming for certain that the bike does/doesn't have a speed sensor independent of the wheel tone rings. I'll be doing some wrenching around looking, barring that, I also have an FSM on the way. Hopefully there is a way to patch it in without potentially impacting ABS/TC. Granted, this is the first bike I've ever had with them, and I've been riding in cold rain through a canyon to work for the last week without either system activating (TC at 3) so I'm not convinced they're necessary, but I'm not too keen on degrading even unnecessary safety features.

-Jaren

P.S. Excle spreadsheets with analysis

https://drive.google.com/file/d/0Bxx...w?usp=drivesdk
https://drive.google.com/file/d/0Bxx...w?usp=drivesdk

Last edited by USSENTERNCC1701E; 04-29-2016 at 07:01 PM.
USSENTERNCC1701E is offline  
post #2 of 63 Old 04-27-2016, 04:00 PM
Senior Member
 
blueglue's Avatar
 
Join Date: Aug 2015
Location: UK
Posts: 249
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 55 Post(s)
Garage
I just changed my tyre from a 50 to a 55. seemed less of a headache

blueglue is offline  
post #3 of 63 Old 04-27-2016, 04:18 PM Thread Starter
Senior Member
 
USSENTERNCC1701E's Avatar
 
Join Date: Apr 2016
Location: Utah, USA
Posts: 529
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 164 Post(s)
Garage
(Thread Starter)
Quote:
Originally Posted by blueglue View Post
I just changed my tyre from a 50 to a 55. seemed less of a headache
Both, or just rear? (Edit: well, I guess the 50 to 55 would have to be rear only, but did you also change ratio on the front?) Did it impact TC at all (ABS if you have it)?

Side note, that only comes to about a 1.8% correction. Though it'd get it close enough to a 5% error I could do the rest of the correction in my head.

I'm thinking what I may wind up doing, if the only sppeed sensors are the tone rings, is use one of the speedohealer settings at -6.7%, and the other at 0, switching to 0 for inclement weather (where driving a tad slow certainly wouldn't be a bad thing anyway). I'm also wondering if this would make TC and ABS more sensitive, guess that depends on what the tolerance between wheelspeeeds defining slip is.

Last edited by USSENTERNCC1701E; 04-27-2016 at 04:22 PM.
USSENTERNCC1701E is offline  
 
post #4 of 63 Old 04-27-2016, 06:43 PM
Senior Member
 
JeffroGymnast's Avatar
 
Join Date: Feb 2016
Posts: 371
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 161 Post(s)
Garage
Changing to a 55 rear tire should (theoretically) increase circumference by 3.1%.

Tire circumference (in.) = rim_diameter + [(2 x aspect_ratio x section_width)/25.4 mm/in ]

a 190x50x17 is theoretically 24.48"
a 190x55x17 is theoretically 25.23"

circumference increase would then be new circumference / old circumference - 1
= .0306 or about 3.1%

Of course, each brand or model of tire will have a slightly different geometry anyways. Take a look at the 55 rear tire thread; plenty of people have put a 55 on and had no issues with ABS/TC.
USSENTERNCC1701E likes this.
JeffroGymnast is offline  
post #5 of 63 Old 04-27-2016, 06:51 PM
Senior Member
 
Beaker's Avatar
 
Join Date: Oct 2015
Location: Bristol. UK
Posts: 974
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 252 Post(s)
I've put a 55 on too. Don't really care about all the math. My sat Nav can work it out quite nicely. And it can compensate for tread wear, pressure difference and changeable weather.



Sent from my iPhone using Tapatalk

Pull my finger
Beaker is online now  
post #6 of 63 Old 04-27-2016, 06:59 PM Thread Starter
Senior Member
 
USSENTERNCC1701E's Avatar
 
Join Date: Apr 2016
Location: Utah, USA
Posts: 529
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 164 Post(s)
Garage
(Thread Starter)
Quote:
Originally Posted by JeffroGymnast View Post
Changing to a 55 rear tire should (theoretically) increase circumference by 3.1%.
You're absolutely right, I forgot to double the tire profile.

-Jaren
USSENTERNCC1701E is offline  
post #7 of 63 Old 04-27-2016, 06:59 PM
Senior Member
 
mattnz's Avatar
 
Join Date: Jul 2015
Location: New Zealand
Posts: 276
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 108 Post(s)
Quote:
Originally Posted by JeffroGymnast View Post
Changing to a 55 rear tire should (theoretically) increase circumference by 3.1%.

Tire circumference (in.) = rim_diameter + [(2 x aspect_ratio x section_width)/25.4 mm/in ]

a 190x50x17 is theoretically 24.48"
a 190x55x17 is theoretically 25.23"

circumference increase would then be new circumference / old circumference - 1
= .0306 or about 3.1%
Yep. With a 55 on my speedo now reads 103 instead of 100 at same gear and revs.
mattnz is offline  
post #8 of 63 Old 04-27-2016, 07:11 PM
Senior Member
 
Join Date: Jul 2015
Posts: 447
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 179 Post(s)
If you really think about it......

Now look, we live in a society where your car must beep until you snap your seat belt in place..

We MUST have signs saying "EXIT" on doors that never close.

With that in mind, can you imagine the outrage, and the legal bill when I claim my new Suzuki caused me to speed. It is defective because when I replaced a tire, it was found the speedometer showed 75 and I was really doing 80.

I'll bet this is why. What make sit even more likely is that the odometer is typically much closer. I fit were off the 6.7%, the 12,000 mile warranty would really mean 12,700....
Beaker likes this.
rcannon409 is offline  
post #9 of 63 Old 04-27-2016, 07:18 PM Thread Starter
Senior Member
 
USSENTERNCC1701E's Avatar
 
Join Date: Apr 2016
Location: Utah, USA
Posts: 529
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 164 Post(s)
Garage
(Thread Starter)
Quote:
Originally Posted by rcannon409 View Post
With that in mind, can you imagine the outrage, and the legal bill when I claim my new Suzuki caused me to speed. It is defective because when I replaced a tire, it was found the speedometer showed 75 and I was really doing 80.
This is exactly why. I remember reading an article, I think it was in Motorcycle Consumer News, about the speedo error, and it is to prevent lawsuits for "vehicle exceeding performance expectations." Which makes no **** sense to me, but whatever.
USSENTERNCC1701E is offline  
post #10 of 63 Old 04-27-2016, 08:28 PM Thread Starter
Senior Member
 
USSENTERNCC1701E's Avatar
 
Join Date: Apr 2016
Location: Utah, USA
Posts: 529
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 164 Post(s)
Garage
(Thread Starter)
Putting the bike on a maintenance stand and running the rear wheel gives no speedometer reading. I did not have a stand available to lift the front, so I disconnected the sensor and ran it by hand across the tone ring. I got a reading, indicating the speedometer reading is dependent only upon the front wheel sensor.

https://youtu.be/jtVa3qBkR7k

Now to track down the wire to somewhere convenient, patch in the speedohealer, and test it all out.

-Jaren
USSENTERNCC1701E is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Suzuki GSXS1000 Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome