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Discussion Starter · #1 ·
So i just swapped my front sprocket out for a 14t this afternoon. I wanted to see how far off my speedo is, so i downloaded the Ulyse speedometer app. I don't have a bar mount for my phone, so i decided to start the app, put my phone in my pocket, take note of my top speed on the ride, and compare it to the saved top speed on the app.....seemed somewhat logical....on my ride, i achieved an indicated top speed on 71mph.....my "guess" was that it should be roughly 69mph...when i got home, the app showed a top speed of 76mph. WTF?!? How is that possible????

2004 Honda 919
1978 Triumph Tiger
1989 Honda GL15 ( A work in progress...)
2014 Honda Grom ( Soon to come)
 

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Discussion Starter · #4 ·
I mean no lie....anywhere approaching 70 feels fast as shit when you're laying on the bars. Lol the highest indicated speed i got out of it before swapping sprockets was 73mph this morning, drafting, tucking, and down hilling. Lol

i thought that a smaller front sprocket would make the speedo read faster than I'm really going, right??

2004 Honda 919
1978 Triumph Tiger
1989 Honda GL15 ( A work in progress...)
2014 Honda Grom ( Soon to come)
 

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With a 14t you are off like 3-4 mph up top.

So 71 was like 68 actual tops.

Your app is wrong. You can't even possibly hit 76 with a stock sprocket before hitting redline.

14t 74 mph is actually 70
 

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It's the magnetic resonance of the flywheel interacting with the accelerometer inside your phone. You have to wait until low tide before it will read correctly. Also, these solar flares are a bitch so you might just want to cover up in a metallic mylar poncho while riding. Or have your wife follow you closely on the met with your phone. Better have her wear a poncho too, just in case.
 

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This is simple. The Grom was probably doing close to 69/70. You had the phone in your shirt pocket. You leaned forward into your tuck at about 6-7 miles per hour. Grom speed plus your leaning forward speed equals a reading of 76 mph on the phone.

PFFFFTTTTT surely you should have known.
 
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Discussion Starter · #10 ·
Update... i did the same thing this morning, hit 72 indicated, and the gps showed a top speed of 69

2004 Honda 919
1978 Triumph Tiger
1989 Honda GL15 ( A work in progress...)
2014 Honda Grom ( Soon to come)
 

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could be while its in your pocket its dropping gps signal.. or do you ride in an area with lots of trees.. it happens to me up here in the mountains all the time.. certain sections just dont have good gps coverage and the app estimates.. when i had my droid with the same app on the handlebars of my ruckus.. it seems pretty darn close most of the time..
 

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It's the magnetic resonance of the flywheel interacting with the accelerometer inside your phone. You have to wait until low tide before it will read correctly. Also, these solar flares are a bitch so you might just want to cover up in a metallic mylar poncho while riding. Or have your wife follow you closely on the met with your phone. Better have her wear a poncho too, just in case.
buwahahahahaha!!!!!!!!!!!!! :cool2:
 

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It's the magnetic resonance of the flywheel interacting with the accelerometer inside your phone. You have to wait until low tide before it will read correctly. Also, these solar flares are a bitch so you might just want to cover up in a metallic mylar poncho while riding. Or have your wife follow you closely on the met with your phone. Better have her wear a poncho too, just in case.

But none of this will give any sort of accurate reading at all unless you remember to tinfoil line your underwear before heading out on your test run.
 

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But none of this will give any sort of accurate reading at all unless you remember to tinfoil line your underwear before heading out on your test run.
The seat is hard enough... now you want to add chafing to the mix? :shocked:
 

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Can you point me in the direction of the poncho? I would like to do further research on this topic.

Sent from the refrigerator using HondaGrom.net mobile app.
 

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That is a little out of my price range... Looks like I will need to bust out the foil and hot glue gun..

Sent from the refrigerator using HondaGrom.net mobile app.
 
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