I was researching chains and sprockets this morning, and on several posts I read that people were running 70mph @ 7k rpm with the stock 15/43 gear set.

My question is; is this true? and if so, I noted today that I'm running 70mph @ 5900 rpm. What kind of sprockets am I running then?

 

I would imagine you have a larger sprocket up front to bring the rpms down? But then again im still new to this stuff.

 

Hmmm, never look at it then, I know Im at 55 at 4100 rpm
I also know I'm stock, I'll check tomorrow and post asap (if it's not raining, it's looking like it)

 

Sounds close to what I have. Throughout sixth gear (until about 80 or so) my RPM is about 1k off from matching my speedo

50mph = 4000rpm+/-
60mph = 5000rpm+/-
70mph = 6000rpm+/-

Faster I go the gap gets a little larger I believe.

 

I guess there's a margin of engine rotations difference, I just checked and mine is around 5200 going 70. Are you sure you're in 6th gear?

 

First of all, your speedo can be off by up to 10%. I have the stock 15/43, and I know my odometer is 4% high, from comparing it to the mile markers on the side of the highway, so I assume my speedo is high by the same amount.

In 6th gear I am a bit over 50 mph indicated at 4,000 RPM, 65 mph indicated at 5,000 RPM, and a little over 75 indicated at 6,000.