Excel speed chart

[Trafficjamz]

Just something I whipped up in excel this after noon

This chart is loosely based on a 90/90 tire.

It shows what speeds you can expect with different gears and rpm's.

Maybe it will help someone out.

[evilone]

Looks really handy

[Trafficjamz]

Photo bucket keeps resizing it too small to read

[evilone]

I saved it and up-sized it using Microsoft office picture manager. It made it just big enough to read before it got blurry.

[Trafficjamz]

bigger font

500 rpm scale

[mousewheels]

Nice:

We've been working on similar info - I made a chart along with the table, but had not posted yet. Was going to measure other tires and make a family of tables and graphs.

Anyhow, for the tables and graphs we can put them into the 'wiki, rather than a photo. Will read nice and clear from there.


--- Edit: 01/25/2011 ---
Original graph has been replaced.
Reason: 90/90 tire dia was incorrect. Now using 16.36in
Note: Fixes problem noted later in this thread.

Wheel_RPM_Graph.jpg (201.84 KiB) Viewed 9067 times

[Trafficjamz]

That's Better

[mousewheels]

1st class

--
A quick check shows our calculations are within about 0.3%. Probably just tire circumference assumption.
Our tables and graphs differ in choice of dependent (y) vs independent (x) axis. IMHO both layouts have merits.


--- Edit: 01/25/2011 ---
Original chart has been replaced.
Reason: 90/90 tire dia was incorrect. Now using 16.36in
Note: Fixes problem noted later in this thread.

Wheel_RPM_Calculation_4.jpg (287.67 KiB) Viewed 9067 times

[Trafficjamz]

My chart assumes a tire circumference of 49.455 inches.

[mousewheels]

My chart assumes a tire circumference of 49.455 inches.

I used 49.23 inches. Pretty much covers it. I'd meant to say "A quick check shows our calculations are within about 0.3%. Probably just tire circumference assumption." Can't hardly expect to be that close

[Wheelman-111]

Greetings:

This is great, Dawgs! Some Empiric observations:

The 90/90 has a nominal height of 3.18". Multiply by 2 and add the 10" rim and you get 16.36. Times pi and you're right at 51" inches circumference, give or take. The 3.50s calculate to 53" circumference.

I actually measured one - can't recall which - with a drop of paint and got 52", so maybe 49" is close for 3.00s but too pessimistic for the bigger skins?

With 7.97:1s and a Giant 97mm Drive Face, Flash 3.2 went 66.3 MPH turning a bit over 10K - again, not sure due to failiing Wheel-sight and gale-force tears in the goggles. I suspect there's a good percentage of belt slip and tire grip loss. The faster you go, the more the slip/slop factor as the wind drag pressure increases.

[mousewheels]

Great catch Wheelman - thanks for checking!
Yeah, circumference is off. Will fix once at home. Also - good input on Flash, belt slippage and other factors causing RPM to not track the charts.

[eliteguy50]

It would be great to develop some sort of a camera to mount inside the belt cover so we could see where the belt is riding on the pulley at the moment of top speed.

[evilone]

I did that. Only it wasn't in the cover, i had the rear half of the af16 cover off.

[Petrock's 1984 Spree]

I remember seeing somewhere on youtube that some guys actually put a high speed camera in the jug of a 4 stroke engine. Then they ran it and you could see the different strokes and the valves move, combustion, etc. It was really cool. Ovbiously it wouldnt be that extreme but same concept