[zimmemr]

Unfortunately your short version does not answer any of my questions.
I understand what gearing does, that is not what I asked.
I have not read Mr. Camerons book but I doubt it mentions the RE650 in particular and how changing the exhaust affects it's ability to pull higher gearing.
I am sure the book will have the means to show you how to calculate the end result if you have all the information,  we don't have it, until we do, the book won't help much.
With so many variables, the more facts we get the more people can get an idea what to expect with different modifications. It doesn't matter whether a modification feels better or worse, that is subjective and only relative to their particular needs/objectives.
For pure street riding I'll start off with a bit of info I have so far found.
With stock gearing in 5th gear my bike could hit the rev limiter showing 105mph. With the 16tooth sprocket it will only pull 7200 revs however the the speed has risen to 110mph. This was done with me crouched down as much as possible.
I am only 5'6" 160lbs riding a GT on OE tyres with the TEC Stinger exhaust system, free flowing air filter and booster plug.

It seems to me you've answered your own question here. That's not meant to sound snarky, but as you point out there are a lot of variables so your results and my results when modifying our motorcycles will always vary. What won't vary are the basics. I.E. If you modify your bike to produce more power you can pull higher gears. Once you know that, the rest of the discussion from my point of view is just talk. Sorry to have offended you, that wasn't my intent. 

[NJ Mike]

I installed a new chain and sprockets yesterday, and put on a 16T front. Rode home about 75 miles from my friends place in PA to NJ on backroads and interstates. First gear feels a bit tall from a standstill, but more useful once under way. Everywhere else the bike just seems more relaxed, especially at speed on the interstate where it doesn't seem to have any problems pulling when turning at 4k and over.

I have the DNA filter, no snorkel and the S&S cans with the db killers in. I'll need to get to the point where I stop thinking about it and just ride it before I can really make any real determination as to whether or not I'll keep it on or go back to 15T.

[supercub]

After riding my new GT 100 miles, I think the stock gearing is perfect.

[ideola]

I couldn't find any info online about how to actually change the sprocket, so here's a how-to in a single sentence: the chain can stay on but you need to loosen the rear wheel right off to get enough slack, the gear selector needs to come off to allow the sprocket cover to be removed (so mark the position with paint/permanent marker), and the 30mm bolt needs torqueing to 145Nm afterwards.

Thanks for this.

Does anyone have a more complete "how-to"? I'm not new to wrenching, but relatively new to motorcycles. I'm sure I can figure it out, but would be helpful to have more detailed instructions...

[biscot]

Just getting ready to install the 16T as I do my  15 k mile service. Hop0ng to feel a bit more relaxed at 70 mph - will report back when I test it out.

[NJ Mike]

Just getting ready to install the 16T as I do my  15 k mile service. Hop0ng to feel a bit more relaxed at 70 mph - will report back when I test it out.

At 70 you'll be pulling 4000 rpm instead of 4500.

[NVDucati]

I've upgraded to the 16 tooth sprocket and yes, I like it a lot - no longer am I constantly looking for a 7th gear.  It has taken just a little fizz out of it's acceleration though, so if I spent all my time racing around city centres I'd leave it on 15.  Would also not consider it if I was carrying pillions.

I couldn't find any info online about how to actually change the sprocket, so here's a how-to in a single sentence: the chain can stay on but you need to loosen the rear wheel right off to get enough slack, the gear selector needs to come off to allow the sprocket cover to be removed (so mark the position with paint/permanent marker), and the 30mm bolt needs torqueing to 145Nm afterwards.

Some folks might find it handy to loosen the counter shaft sprocket nut before loosening the rear axle.

[Hoiho]

Thanks for this.

Does anyone have a more complete "how-to"? I'm not new to wrenching, but relatively new to motorcycles. I'm sure I can figure it out, but would be helpful to have more detailed instructions...

This guy is very good at explaining things well https://www.youtube.com/watch?v=UxD3qdD7LhE

[ideola]

This guy is very good at explaining things well https://www.youtube.com/watch?v=UxD3qdD7LhE

Fantastic video, thanks for sharing!

[Royal Low]

Well I pulled the trigger and did the 16t sprocket swap on 6/30/21. Was an ez 20 min swap. Took my 2021 Cont GT for a ride after the swap and to me it was the best mechanical mod Iv done to the bike so far. The bike is still very responsive and it didnt loose much acceleration at all. I like the gears being a bit longer and love that the RPM are much lower at 70-80 mph.

[ideola]

Ordered mine this week, looking forward to digging in!

[ATXConti650]

Just installed the 16T countershaft sprocket and the bike really has taken to it well.   No more trying to shift into '7th' gear and the gearing in 5th now is almost identical to the stock 15T in 6th.   Engine pulls the additional gearing just fine and to my senses it feels happier with the slightly taller gear.   60 mph is showing 3600 revs in 6th and I've always liked tall gearing....because you can always downshift if you want more revs but once you've run out of gears you can't upshift to lower them.   Stock chain fit just fine and the 17T might actually fit...but unless the motor finds more torque I'm going to leave it at 16T...a very happy setup.

Finished installing 16T sprocket yesterday using stock chain, 1st gear has longer legs now, highway speed is smoother it seems, and I like the feel of the bike. Acceleration was plenty fast for me with the stock sprocket and it still pulls strong as far as I'm concerned. 6th gear at 80 runs about 5K RPM.

Got it from Hitchcock's and took a week or so to arrive in Texas by mail without special shipping.

[CPJS]

Well I pulled the trigger and did the 16t sprocket swap on 6/30/21. Was an ez 20 min swap. Took my 2021 Cont GT for a ride after the swap and to me it was the best mechanical mod Iv done to the bike so far. The bike is still very responsive and it didnt loose much acceleration at all. I like the gears being a bit longer and love that the RPM are much lower at 70-80 mph.

It is a great mod, for me, it feels how it should have been geared in the first place as it still pulls all the gears easily.