16T vs 15T sprockets

cayuse · 05-20-2011, 02:45 PM

OK, I'm eating my words a little here, but I now have to say there is a good argument for using the stock 15T front sprocket.

I converted my bike over the winter to the 16T sprocket and I've run it now for a couple of months and for the most part I just love it.
It stretches out the lower gears very nicely so 1st is good for more than just 10 feet and 2,3, and 4 have really nice torque at speeds
that feel really comfortable. So, for motoring around town and between towns on the secondary roads it’s perfect. The only problem is 5th gear.

The GZ doesn’t have a lot of power anyway but it really is crippled with the 16T sprocket at speeds over 100kph (60mph).
I found I could achieve speeds up to about 110kph (70mph) as long as the road was flat or downhill and the wind was not against me.
I couldn’t get mine to go faster than that without a tailwind. Throw in some hilly terrain and I’m downshifting very quickly to 4th
to keep up with (most) traffic. When that happens, fuel mileage goes out the window. This season I’m hitting the open road more
often so these experiences are somewhat disappointing. I was even starting to shop for a (gasp!) bigger bike.
But then I remembered everyone here saying the top speed would probably be reduced with the taller sprocket so I thought I would give the 15T another chance.

So, to do a fair comparison, I put the 15T sprocket back on and tried my work commute a couple of times on Hwy 1, the local “freeway”.
It’s hilly, everyone’s driving at 110-120kph and there is a little wind here and there so it’s a pretty good test. I don’t normally commute
on this route because, except for the speed, it’s pretty boring. Guess what? I’m keeping up with all the traffic, and no downshifting on
the hills! I’m even passing!! Of course the downside rears its ugly head: 1st gear is very short, I’m tempted to skip it and take off in 2nd
unless I’m parked on a hill, and all the other gears seem just a little short too.

So, what am I going to do? I’m going to stay with the 15T for a couple of weeks and make another run up into the mountains to give it a real good test.
If it works out the way I think it will I will probably switch back to the 16T sprocket and reserve the 15T unit for occasional ‘road trips’ into the mountains.
The 16T option is just too nice to give up for the local riding I do 95% of the time.
I can change the sprocket and tension the chain in a ½ hour so it’s not a big deal.

FLAJIM · 07-09-2015, 07:45 PM

Bought the bike for my wife to learn on. With the 16T she using all the gears longer which will help her transfer to a larger bike down the road. For me, at 235 I can ride at 55 mph 4500 rpm and getting 68 mpg. Sorry but I just don't like taking this bike faster than 55 but that just me.

Be Safe JIM

spldart · 07-09-2015, 10:40 PM

I installed the 16t sprocket a while ago. I'm loving the lower rpm at freeway speed and my mileage is unchanged. 68 to 80 mpg. 70 to 75 seems to be my average. Before and after
the upgrade.
My thinking is this. As FLAJIM mentioned you now only turn 4500 rpm to do 55 mph.
This equates to one very important fact....
Lower ring speed.

Winding out a motor is bad for components and one of the important ones is your rings...
...And your valvetrain... Anywho...
We know redline is prolly 8k to 8.5k rpm but the engine can't live long at high rev.
So this mod and keeping your speed below 65mph is a great way to increase longevity
imho.

Water Warrior 2 · 07-10-2015, 05:41 PM

If I remember correctly the British auto industry would list piston travel in there advertising and owners manual. Never thought much of it at the time but it makes sense from a reliability standpoint. Yeah, we are going back a few decades. Modern engines in cars don't seem to worry about piston travel. Better materials and oils make things last longer. Oops, should include much better research and design too.
What was once considered an exotic design such as roller cams, overhead cams and roller rocker arms were for the rich and famous willing to spend the $. These designs are very common place now for their longevity and reliability.
The GZ may suffer from an older design but it is also the reason it is a popular machine. It is much simpler and fits well with it's target market.

spldart · 07-10-2015, 09:45 PM

One thing between bike and car motors... Rev's
Piston ring speed peaks at half way between top and bottom stroke positions.
It is not only a matter of stroke measurement but the revolutions per.
Both rpm and stroke length are involved in calculating ring speed.

Why do I now feel sullied after that statement?

05-20-2011, 02:45 PM	#1
cayuse Senior Member Join Date: May 2010 Location: Abbotsford, BC Posts: 444	16T vs 15T sprockets OK, I'm eating my words a little here, but I now have to say there is a good argument for using the stock 15T front sprocket. I converted my bike over the winter to the 16T sprocket and I've run it now for a couple of months and for the most part I just love it. It stretches out the lower gears very nicely so 1st is good for more than just 10 feet and 2,3, and 4 have really nice torque at speeds that feel really comfortable. So, for motoring around town and between towns on the secondary roads it’s perfect. The only problem is 5th gear. The GZ doesn’t have a lot of power anyway but it really is crippled with the 16T sprocket at speeds over 100kph (60mph). I found I could achieve speeds up to about 110kph (70mph) as long as the road was flat or downhill and the wind was not against me. I couldn’t get mine to go faster than that without a tailwind. Throw in some hilly terrain and I’m downshifting very quickly to 4th to keep up with (most) traffic. When that happens, fuel mileage goes out the window. This season I’m hitting the open road more often so these experiences are somewhat disappointing. I was even starting to shop for a (gasp!) bigger bike. But then I remembered everyone here saying the top speed would probably be reduced with the taller sprocket so I thought I would give the 15T another chance. So, to do a fair comparison, I put the 15T sprocket back on and tried my work commute a couple of times on Hwy 1, the local “freeway”. It’s hilly, everyone’s driving at 110-120kph and there is a little wind here and there so it’s a pretty good test. I don’t normally commute on this route because, except for the speed, it’s pretty boring. Guess what? I’m keeping up with all the traffic, and no downshifting on the hills! I’m even passing!! Of course the downside rears its ugly head: 1st gear is very short, I’m tempted to skip it and take off in 2nd unless I’m parked on a hill, and all the other gears seem just a little short too. So, what am I going to do? I’m going to stay with the 15T for a couple of weeks and make another run up into the mountains to give it a real good test. If it works out the way I think it will I will probably switch back to the 16T sprocket and reserve the 15T unit for occasional ‘road trips’ into the mountains. The 16T option is just too nice to give up for the local riding I do 95% of the time. I can change the sprocket and tension the chain in a ½ hour so it’s not a big deal. __________________ Lovin' every minute of it. 2005 GZ250 (sold after 26000km) 2013 CB500XA Login or Register to Remove Ads
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07-09-2015, 10:40 PM	#3
spldart Senior Member Join Date: May 2015 Location: Stafford, Texas Posts: 604	I installed the 16t sprocket a while ago. I'm loving the lower rpm at freeway speed and my mileage is unchanged. 68 to 80 mpg. 70 to 75 seems to be my average. Before and after the upgrade. My thinking is this. As FLAJIM mentioned you now only turn 4500 rpm to do 55 mph. This equates to one very important fact.... Lower ring speed. Winding out a motor is bad for components and one of the important ones is your rings... ...And your valvetrain... Anywho... We know redline is prolly 8k to 8.5k rpm but the engine can't live long at high rev. So this mod and keeping your speed below 65mph is a great way to increase longevity imho. Login or Register to Remove Ads
	0

07-10-2015, 09:45 PM	#5
spldart Senior Member Join Date: May 2015 Location: Stafford, Texas Posts: 604	One thing between bike and car motors... Rev's Piston ring speed peaks at half way between top and bottom stroke positions. It is not only a matter of stroke measurement but the revolutions per. Both rpm and stroke length are involved in calculating ring speed. Why do I now feel sullied after that statement? Login or Register to Remove Ads
	0

07-09-2015, 07:45 PM	#2
FLAJIM Member Join Date: Apr 2011 Location: Daytona Beach Posts: 87	Bought the bike for my wife to learn on. With the 16T she using all the gears longer which will help her transfer to a larger bike down the road. For me, at 235 I can ride at 55 mph 4500 rpm and getting 68 mpg. Sorry but I just don't like taking this bike faster than 55 but that just me. Be Safe JIM
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07-10-2015, 05:41 PM	#4
Water Warrior 2 Senior Member Join Date: Dec 2006 Location: Squamish B.C Canada Posts: 11,409	If I remember correctly the British auto industry would list piston travel in there advertising and owners manual. Never thought much of it at the time but it makes sense from a reliability standpoint. Yeah, we are going back a few decades. Modern engines in cars don't seem to worry about piston travel. Better materials and oils make things last longer. Oops, should include much better research and design too. What was once considered an exotic design such as roller cams, overhead cams and roller rocker arms were for the rich and famous willing to spend the $. These designs are very common place now for their longevity and reliability. The GZ may suffer from an older design but it is also the reason it is a popular machine. It is much simpler and fits well with it's target market.
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