Maths genius required! (Bike related but long)

I *could* work it out, but can't tax the old brain too much at the moment as
any brain work might unsettle my current 'unemployed and happy' mindset...

Anyway, got the missus' R6 it's 4 year service recently and then had the
thing finally set up on a dyno. It also needed new chain and sprockets so I
asked the dyno bods to sort that.

But they didn't get a standard set and the gearbox sprocket is now down by 1
tooth.

Although I didn't ask for this to be done and could, therefore, get a std
size fitted, it's made the R6 everything it always should have been.

The 98.9bhp (with over 95 from just over 11 to 15,000rpm) now makes the
front lift on the throttle in 2nd (if you give it beans at 9k...) and it
pulls strongly all the way through each gear.

So it's load more fun, if a tad more nervous, to ride. But the R6 speedo is
driven off the gearbox sprocket.

So I want to know what kind of mental maths is required to work out actual
speed.... I can't remember the std front/rear sprocket sizes so am guessing
at an approximate 7-10% overread. And erring on the high side as I got an
indicated 180mph yesterday which I know is way way too fast for an R6...

So, anyway. In a nutshell, what speeds will the speedo be recording at 30,
40, 60 and 70 mph etc now so I can ensure that when the bikes being ridden
I/the missus ain't holding up the traffic cos we're well under the limit.

TIA

Dave

 

If the standard sprocket is 15 teeth and you have a 14 then your speed
will be 14/15 or 93.333% of the speedo reading, assuming the speedo was
accurate to begin with.

The speedo will read 15/14 or 107.14% of the actual speed.

At 30 mph the speedo will read 32.14mph
40, 42.86
50, 53.57
60, 64.29
70, 75
140, 150

If the speedo was optimistic to start with, it will be even more so now.

Better to ask Mr. Plod where the local measured half-mile is
and calibrate it on that with a stopwatch.

 

A standard sprocket is apparently 16 teeth so your 15 tooth one will cause
the speedo to overread by 6.67%

32 , 43 , 64 , 75
--
Alex

YZF 600

"I laugh in the face of danger"

"Then I hide until it goes away"

www.upce.org.uk
www.drzoidberg.co.uk

 

On the other hand, if the standard front sprocket is 16 teeth
you can do the calculations yourself....

 

But that means that the 180 *and_still_pulling* was around 168 on the old
speedo readings..... So it must've been reading high to start with, yeah?
I hope...

 

Borrow a GPS and look for a constant speed in a straight line with
that, check speedo at the given speed and bob's yer uncle.

 

I'm thick, so I think, since the speedo is connected to the frontwheel, it
doesn't really matter, does it. It reads the speed from the frontwheel and
if the bike has to do less revs to get to speed, it's just that.....

--
Spete
www.gimmemoney.mine.nu
www.spete.homeip.net

Occasionally, I'll be consistent

 

The clue is in the question.

 

And?

--
Spete
www.gimmemoney.mine.nu
www.spete.homeip.net

Occasionally, I'll be consistent

 

"So it's load more fun, if a tad more nervous, to ride. But the R6 speedo is
driven off the gearbox sprocket." is my giveaway line in the original post,
I reckon.....

Dave

 

Ah, right, missed that bit. As I were then...

--
Spete
www.gimmemoney.mine.nu
www.spete.homeip.net

Occasionally, I'll be consistent