Shimano E8000 speed vs Garmin?

Shaun

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May 12, 2018
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Saint Mary Bourne
#1
Had a fun ride today but came across a difference in speed between my Garmin Edge 1000 and the steps display. At the point the Steps display indicates the cut off limit at 15.5mph the Garmin is reading 14mph. At the end of the ride the steps display indicated total of 42.8miles compared to the Garmin reading 39 miles. I know in the Specialized Misson Control app you can fine tune the wheel circumference to get correlation but am unable to find a way with the Shimano system?

Any wise members able to offer words of wisdom to correct my issue as I now feel cheated that the limiter is cutting in lower than the legal requirement?
 
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stiv674

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#2
Had a fun ride today but came across a difference in speed between my Garmin Edge 1000 and the steps display. At the point the Steps display indicates the cut off limit at 15.5mph the Garmin is reading 14mph. At the end of the ride the steps display indicated total of 42.8miles compared to the Garmin reading 39 miles. I know in the Specialized Misson Control app you can fine tune the wheel circumference to get correlation but am unable to find a way with the Shimano system?

Any wise members able to offer words of wisdom to correct my issue as I now feel cheated that the limiter is cutting in lower than the legal requirement?
I haven't noticed the 'live' speed issue as I only rely on the shimano display but the total distance is always about 4 or 5 percent higher according to the bike compared to my GPS tracking.

Bit annoying if it is that much out though. Especially as I thought I had broke the 40mph barrier on Saturday :p
 

Shaun

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#3
I haven't noticed the 'live' speed issue as I only rely on the shimano display but the total distance is always about 4 or 5 percent higher according to the bike compared to my GPS tracking.

Bit annoying if it is that much out though. Especially as I thought I had broke the 40mph barrier on Saturday :p
Mine is closer to 9% error which is very annoying and it does not appear any obvious way to correct it with the current user available tools?
 

stiv674

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#4
Mine is closer to 9% error which is very annoying and it does not appear any obvious way to correct it with the current user available tools?
I haven't looked into it really, sort of hoping it was the GPS that was wrong...

Could contact shimano I guess although I doubt they'll respond. I wonder if all systems are affected...
 

Shaun

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#5
I haven't looked into it really, sort of hoping it was the GPS that was wrong...

Could contact shimano I guess although I doubt they'll respond. I wonder if all systems are affected...
GPS accuracy with a good clear view of the satellites is considered highly accurate by those in the know. I believe the inability to tune the true wheel rolling circumference in the Shimano software is the limitation. The accuracy per bike platform, will ultimately depend on the difference from actual rolling wheel circumference to the default software value set in the Shimano software.
 

stiv674

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#6
GPS accuracy with a good clear view of the satellites is considered highly accurate by those in the know. I believe the inability to tune the true wheel rolling circumference in the Shimano software is the limitation. The accuracy per bike platform, will ultimately depend on the difference from actual rolling wheel circumference to the default software value set in the Shimano software.
Yeah you're right, I was just hoping as it now means I've ridden less than I thought:confused:

I've 'askedembn' so maybe they might try to answer. Other than that I'm not sure what else can be done...
 

Shaun

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#7
Excellent move to ask embn...I'm sure there are a great many Shimano owners who would benefit from this being resolved by Shimano and embn is a great platform to flag it up.
 

R120

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#8
Why not use sat nave app like Waze on your phone to get a real time reading?
 

Shaun

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#9
The Garmin Edge 1000 uses its internal GPS like Waze does with your phone, to provide a speed reading. As the Shimano Steps system does not allow me to record my ride on the E8000 I doubled up and attached my Garmin for this weekends rides. It was only then that I came across this issue.
 

R120

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#10
I meant more of a way as checking the Garmin accuracy - I once in a moment of boredom decided to check the speed reading on Waze, on a Tom Tom Sat Nav, and on a Garmin sat nav in my car, and none of them read the same MPH
 

Shaun

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#11
Okay understood. I'll give it a go and see if it agrees more with the Garmin of Shimano reading...
 

R120

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#12
I suspect you are right - as an fyi I believe you can alter the wheels size by the Laptop software, using the SM-PCE1 module. Most decent shops should have this equipment as it is the same as used for setting up DI2 gearing

Bit more info in this thread:

Updates and fine tuning - EMTB Forums
 

stiv674

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#13
I would have thought the accuracy of the Garmin was at least as good a phone app :unsure:
 

Shaun

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#14
I suspect you are right - as an fyi I believe you can alter the wheels size by the Laptop software, using the SM-PCE1 module. Most decent shops should have this equipment as it is the same as used for setting up DI2 gearing

Bit more info in this thread:

Updates and fine tuning - EMTB Forums
Thanks for this. The bike is due for its complimentary first check in the coming weeks, so I'll discuss with the bike shop to see if they can correct the error.
 

stiv674

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#15
Thanks for this. The bike is due for its complimentary first check in the coming weeks, so I'll discuss with the bike shop to see if they can correct the error.
It will be interesting to know the outcome :unsure:
 
Nov 7, 2018
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#16
I meant more of a way as checking the Garmin accuracy - I once in a moment of boredom decided to check the speed reading on Waze, on a Tom Tom Sat Nav, and on a Garmin sat nav in my car, and none of them read the same MPH
I would expect a stand alone GPS device such as a Garmin would be far superior to any phone based app if set up correctly. Most Garmin devices can take a reading every second but phones are a reading maybe every 3 seconds or so to preserve battery life.
 
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Peaky Rider

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#17
Am I correct in thinking that if you ride under thick cover, e.g. a pine forest, your Garmin will be unable to track any zig-zagging you make and will simply calculate the distance travelled in a straight line from where contact was lost and regained?
 

Shaun

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#18
Indeed it will simply assume a straight line between its last known position and its next received signal position.
 
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#19
Am I correct in thinking that if you ride under thick cover, e.g. a pine forest, your Garmin will be unable to track any zig-zagging you make and will simply calculate the distance travelled in a straight line from where contact was lost and regained?
No, I do pretty much all of my riding within forests (Coed Y Brenin, Cannock Chase, Llandegla, Nant Y Arian to mention a few) and it tracks fine, For best results you need to set the Garmin to 1 second recording. The default is smart recording, fine for road use where you're travelling in one direction for minutes on end but 1 second recording is needed for mountain biking. I'd say a phone will loose a signal before any GPS device as a phone is jack of all trades so to speak.

On occasion I have lost signal (once or twice in several years) but I'd imagine that's more to do with the satellites.
 

Shaun

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#20
No, I do pretty much all of my riding within forests (Coed Y Brenin, Cannock Chase, Llandegla, Nant Y Arian to mention a few) and it tracks fine, For best results you need to set the Garmin to 1 second recording. The default is smart recording, fine for road use where you're travelling in one direction for minutes on end but 1 second recording is needed for mountain biking. I'd say a phone will loose a signal before any GPS device as a phone is jack of all trades so to speak.

On occasion I have lost signal (once or twice in several years) but I'd imagine that's more to do with the satellites.
My comment for clarity assumed satellite loss and how a GPS device displays this. I agree that this is thankfully a rare event these days.
 
Nov 7, 2018
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#21
Yes, sorry Shaun, If the signal is lost a straight line will be inserted once the signal is regained.

Peaky rider, GPS devices and phones will track you through most forests fine.
 

R120

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#22
I would expect a stand alone GPS device such as a Garmin would be far superior to any phone based app if set up correctly. Most Garmin devices can take a reading every second but phones are a reading maybe every 3 seconds or so to preserve battery life.
I agree with you, but having worked in construction for 20 years I have seen multiple instances where the tool being used to measure or check for an inconsistency is not properly calibrated or is out itself, so I was merely suggesting check the Garmin is working properly, and not giving out a false reading, however unlikely.
 
Nov 7, 2018
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#23
My Garmin can be set up by wheel circumference for each bike. The way I usually do this is by putting a blob of paint or grease etc on the tyre then rolling the bike in a straight line and finally measure the distance between the two marks. I think this method is probably the best way to calibrate it.

I suppose errors can creep into GPS devices if the magnet and sensor are a little out of alignment and it misses a revolution or two. I have the hub mounted sensors now but I'm not sure how accurate they are compared to the chainstay/magnet sensor type.

Changing the tyre size/tread will mess up the speed on any system but it shouldn't be by much.
 

R120

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#24
I am interested to see the results on this, because it could mean a lot of bikes are cutting out below the limit
 

Gary

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#25
I am interested to see the results on this, because it could mean a lot of bikes are cutting out below the limit
Mine always has.
it was around 13.5-14mph when new and became 14-14.5 after an update (I forget which one)
I also have always run 2.3/2.4 rear tyres though.

tested on open rural roads with no trees/buildings BTW
Using tomtom and Garmin GPS simultaniously (I know, what a geek)

Oh... and my Garmin is calibrated by wheel sensor as well as GPS.
 
Nov 7, 2018
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#26
I've been looking through the manuals for the etube software and I can't see anywhere to change wheel diameter, if fact other than diagnostics I can't see anything you can do in the pc software that you can't do via the app.
 

Shaun

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#27
The only place I have seen it mentioned is in the PC E-Tube Project Software under report where it lists the parameter wheel circumference...
wheel-circumference-jpg.12267
This would indicate that a dealer with the E-Tube Project interface and software could update this field to correct the real vs indicated for Shimano systems whilst maintain legal integrity. I feel we should get what it is we paid for 25 km/h not 9% lower as is my situation.
 
Feb 11, 2019
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#28
Following this logic of how the 'ebike brain' works, a 2.068m cir. tyre running at 201.5rpm is 25kmh (416.6m/min) So the electronic limiter for this tyre size is 201.5rpm as the 'brain' has no other data to establish this with.

If the tyre cir. value is changed to 1.8m (while still running a tyre with 2.068m cir) the motor will think the limit is 231.5rpm to maintain a 25km/h limit. All the while 231.5rpm x 2.068m is equivalent to 478m/min or 28.7km/h (i.e. breaking the law - discussion for another time).

Very interesting to know if the dealer can actually change the tyre circumference value....
 
Nov 7, 2018
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Focus Jam2
#29
Today I connected my laptop up to my Focus Jam2 via the SM-PCE1. I used the Etube software as the interface to access the bike details etc. As I thought the settings you can change are the same as via the phone app. You can however get more details from the bike as seen in Shauns post earlier.

The circumference on my bike is factory set and is 2300mm.

I then connected via Freemax software and lowered the assistance level on ECO to 40% from 60%, set trail to 50% and boost to 100%. I have left all the torque levels at factory defaults.

If you wanted to change the wheel circumference you would have to pay for the minimax software, This is per bike and over £100. You can also raise the speed limit to the USA level via a toggle if you wanted. I'm only interested in having the motor cut out at the correct speed but this is too much for me to pay for such a minor niggle. I do believe that Shimano should allow us some adjustment for different tyre sizes, I'd imagine a 100mm would suffice.

I'm not sure if the dealers have access to different software.
 

Shaun

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May 12, 2018
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Saint Mary Bourne
#30
Today I connected my laptop up to my Focus Jam2 via the SM-PCE1. I used the Etube software as the interface to access the bike details etc. As I thought the settings you can change are the same as via the phone app. You can however get more details from the bike as seen in Shauns post earlier.

The circumference on my bike is factory set and is 2300mm.

I then connected via Freemax software and lowered the assistance level on ECO to 40% from 60%, set trail to 50% and boost to 100%. I have left all the torque levels at factory defaults.

If you wanted to change the wheel circumference you would have to pay for the minimax software, This is per bike and over £100. You can also raise the speed limit to the USA level via a toggle if you wanted. I'm only interested in having the motor cut out at the correct speed but this is too much for me to pay for such a minor niggle. I do believe that Shimano should allow us some adjustment for different tyre sizes, I'd imagine a 100mm would suffice.

I'm not sure if the dealers have access to different software.
I also have a Focus Jam2 and the correct tyre circumference for my 650b & 2.8 tyres is 2281.55mm.
wheel-circumference-setting-correction-2-jpg.12282


If I put this figure into an online calculator it shows the figure I would need to correct my indicated verses actual speed. If the default is 2300mm then this explains why the error.
wheel-circumference-setting-correction-jpg.12283
 

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