Tweaking Circumference on Como Bikes to get REAL 20mph speed

[Uburoibob]

Today, I got the software on my 2020 Como 3.0 officially installed (new bike from Specialized to replace my 2.0 with the cracked frame).

When doing it, I asked them to set the wheel circumference to 2200 instead of 2293 (the stock size).

The reason is that when my old 2.0 indicated it was going 20mph on its display, my GPS showed I was actually doing 17.5 mph. By having my LBS reduce the circumference to 2200, I now get 18.5 mph when the bike shows 19.5 (where the pedal assist stops). I will be heading back up there to have them take it down to 2100, I think. The goal is to get a REAL 20 mph from the bike and have the GPS and bike displays showing the same info.

Or perhaps I'll have them take it down to 2000 (the lowest setting) and go a little bit over the 20 mph limit. Not sure yet. What would you do?

Sure wish they'd let US change that. Or at least that they'd set the software properly from the factory...

 

[ChezCheese:)]

I read that if your reduce the wheel size to 18inches and have the display show kilometers, that the resultant number will actually be your actual speed in miles. Dont know if it works.

 

[Uburoibob]

Hmmmm...interesting. More than anything, I'd just like the speed of the bike to be accurate to the GPS (iPhone, Apple Watch, and Garmin Explore 1000)...looks like the lowest it will go is a circumference of 78.74016 inches. That's down from the stock size setting of 90.27559 inches (or 2293 mm).

 

[ChezCheese:)]

Sorry - - diameter!

 

[Uburoibob]

That would be circumference of 56.5487 inches. the Turbo software, while it used to let you put any measurement in there, now limits it between 2000 and 3000 mm. Which is roughly a range of 78 and 90 inches circumference or 24 to 28 inch diameter.

 

[Ron49]

We just received two 2020 model Como 3.0s (US) a few weeks ago and the computer speeds and mileages are very close to our iPhones and Apple watches. No idea what the wheel factor is - I’m sure it’s as set by default when dealer updated software prior to delivery.

 

[Uburoibob]

If you download Mission Control, and select TUNE, it will let you do some wonderful things like setting your standard and power speed thresholds, let you set up SMART RIDE for amortizing the right amount of battery power over longer rides, and it will show you your wheel circumference. I believe stock is 2293. My last Como was 2255. Both showed about 2/2.5 mph over what GPS' were showing. Not sure why. 2293 IS the circumference of a Como stock wheel and tire, so it SHOULD work. But not for me. In any case, tweaking the circumference has me within 1 mph now. One more tweak, and it will be perfect.

 

[Ron49]

If you download Mission Control, and select TUNE, it will let you do some wonderful things like setting your standard and power speed thresholds, let you set up SMART RIDE for amortizing the right amount of battery power over longer rides, and it will show you your wheel circumference. I believe stock is 2293. ...

Thanks - just learned something new. Went and checked ours and they're both set to 2190.

 

[Uburoibob]

WOW! Thanks for that info! Sounds like your local bike store knew to plug that number in. As I said, I am very close with 2200. I'll have them change it to 2190. That saves me a lot of trial and error!

 

[Ron49]

WOW! Thanks for that info! Sounds like your local bike store knew to plug that number in. As I said, I am very close with 2200. I'll have them change it to 2190. That saves me a lot of trial and error!

I run the tires at 35-psi and weigh ~192-lbs; speed and mileage are very accurate.

 

[Uburoibob]

I run my tires at 35 as well but have an extra 10 lbs on you. And I am 6'. M/L frame on bike. So, yeah, I think that's the magic number.

 

[Uburoibob]

I have my ECO set up for 35/55, SPORT set up for 60/80, and TURBO set up for 80/100.