Trying to figure out Gearing Commander.com

[SandyN]

I too, am now confused by the figures on Gearing Commander. I've just replaced my sprockets and gone +1 on the rear which equals 2.17%.

On standard sprockets GC shows that 6000 rpm in 6th = 117 km/h. My experience tells me that 120 km/h equals about 7000 rpm. (Speedo reading 132)

When I put my new ratio 16/47 into GC it tells me that 8000 rpm = 152 km/h, which agrees with the speedo, BUT, the GPS shows 136 at 8000!

A true 100 km/h equals 6260 rpm with speedo reading 108: GC says with my setup I should be doing 114 at 6000!

I did test at the other speeds but for the life of me cannot remember the figures at the moment...

 

[FinalImpact]

Sandy,
I made a thread on this topic it has the math and details to calculate your own values. I thought I shared the Excel file, but I don't see it in the thread.

As pointed out in 2013, from new to used, a tire looses 5/32" (0.31" X2 = 0.625") which changes the roll out of the tire. I know this isn't your question but all of the gearing data is in this thread and you can use an on line calculator to verify data. -->> Read This! RPM, Gear, Sprockets, Tire = Actual Speed!

So far every tire I've owned measures 0.25" smaller than what is expected. i.e. more revs to go the same distance.

Forum will not accept Excel file but it will accept MS WORD documents. Download this attachment, save it and REMOVE the .DOC extension. Then it will open properly (if you have MS Excel).

Looks like this.... File Added also. Follow the directions and MEASURE the Roll out of your TIRE!