Just wonder how much and which way will my speedo will be off once i go down one tooth at the front? At the local track in most slow corners 1st gear is too little but second is too much. Hoping get it sorted by going 1 tooth down at the front then 2nd should be just spot on. Cheers

 

The speedo will read faster, probably by about 10-15% higher than you are travelling. There was a chart online that showed how different gearing affected the spedo of a 600rr, I'll have to look for it.

Also, if anyone has the formula for calculating your actual speed at a given RPM and gear, let me know. I have different sprockets on my bike (f3), as well as f4i gauges, and my speedo is reading about 25% high right now...

 

I've got an excel spreadsheet that tells you your actual speed at a given RPM. Shoot me a PM if you want it.

 

Yes, can I change the gear ratios for the F3? Thanks, email it to me at:

johnnyt1118 @ yahoo . com Thanks

 

Id like one to please mate areaboi@gmail.com
Thanks again

 

Check your mail

 

Hey thanks for the spreadsheet.

Few questions about it though. I put in my gearing (14, 45), and it said at 3,500 in 2nd that I would be going 25mph. So i went out and tried it, and the indicated speed was only 23mph (with my assumed 20% error, I was really only going around 18mph). I followed some cars and my indicated speed was between 30 and 32mph in a 25mph zone. Also in 45mph zones my indicated speed is around 58mph. I so figure my speedo reads about 20-25% high. Im going to have a friend drive at 35mph in a car and see what my speedo reads to get a more accurate error measurment.

I double checked all the gear ratios in the formula with my F3 manual, and the spreadsheet seems to be giving me much higher mph per RPM than I see out on the road. Am I doing something wrong?

 

Not sure where you're getting the 25mph in second gear at 3,500rpm, at that speed you should be going 21mph. Also, you're going too slow to figure out the speedo inaccuracy, at a really low mph like 25, the difference might be just a tenth of a mph difference, whereas faster speeds wouldn't have that big of a problem. Go on a freeway and get up to 75mph indicated and record the indicated rpm from several different gears, say 4th-6th gear and then you can figure out a more accurate percentage of speed innacuracy.

Oh, also make sure the rear tire size is set right, the default is a 160/60/17

 

Yea I just measured the circumfrence of my rear tire (6.45052ft) and calculated on some paper that at 2,800 in 3rd I would be going 20.8 mph. Then I set the tread depth % on the chart to 60% giving me 21mph in 3rd on the chart. I had it originally set to 95% because it is a brand new rear tire. Guess it helps to know the forumlas before I start plugging in RPMs and speed

I'm just using this chart as a refrence for now, as I live down the street from a police station and I'm not trying to be getting tickets due to my speedo.

 

If you're right down the street from cops, ask them to radar you. I've done it before in my car when I had the wrong tires on it. Cops are people too, they can be nice.