ST1100 Speed vs RPM

Whooshka

Whooshka

Fairly faST old guy
Joined
Jan 29, 2017
Messages
949
Location
New Jersey
Bike
2006 ST1300
Been watching a discussion on Face Book where guys are saying at 3K RPM they are doing 60 MPH. At 4K RPM they're doing 80 MPH. At 5K they're doing 100.

Is this right? On my 1300 if I remember right at 100 MPH I'd be taching at least 7 grand. Then again it's been a while since I rode.

Is the 1100 geared that high?
 
There’s speedo error mixed in with that.i have to be turning around 3300 rpm for a true 60mph. 3800 gets me close to 75mph in 5th gear
 
1100110013001300
RPMmphkm/hrmphkm/hr
100019.531.418.529.7
200039.162.936.959.4
300058.694.355.489.1
400078.1125.873.8118.8
500097.7157.292.3148.5
6000117.2188.6110.7178.2
7000136.7220.1129.2207.9
8000156.3251.5147.7237.6

I made up a gearing comparison spreadsheet and calculated the speed/rpm for the 1100 and 1300; the overall ratio in top gear (including primary and final) is 4.03 for the 1100 and 3.93 for the 1300. The other difference is the wheel diameter/tyre profile. The numbers feel about right to me, my 1300 certainly spins right around 4000 at my usual 120km/hr cruise speed.
 
Whooshka said:
Been watching a discussion on Face Book where guys are saying at 3K RPM they are doing 60 MPH. At 4K RPM they're doing 80 MPH. At 5K they're doing 100.
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That's pretty close and a good general rule to go by, which will give you a little safety factor depending on how accurate your speedometer is. It's how I determined my speed when my speedometer gear broke down by the axle, until I got it fixed. Using the tach was way more interesting than using my GPS, at least for a little while. ;)

Interestingly enough, after replacing that gear, my speedo is now nearly dead-on, within ±1 mph of my GPS.
 
paulcb said:
That's pretty close and a good general rule to go by, which will give you a little safety factor depending on how accurate your speedometer is. It's how I determined my speed when my speedometer gear broke down by the axle, until I got it fixed. Using the tach was way more interesting than using my GPS, at least for a little while. ;)

Interestingly enough, after replacing that gear, my speedo is now nearly dead-on, within ±1 mph of my GPS.
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I usually go by this:

 
But aerodynamics come into play causing the bike to use more BHP the higher the speed. The RPM to MPH relationship is not linear.

Does an 1100 really do 156 MPH as that chart states?
 
RPM to speed is linear, but the power to get to that RPM is not. I doubt any ST1100 can get to 150+ MPH without significant work.
 
paulcb said:
RPM to speed is linear, but the power to get to that RPM is not. I doubt any ST1100 can get to 150+ MPH without significant work.
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Agreed. Back when my ST 1100 was new, I spent quite a bit of time riding around at high speed on the German autobahns. With a Clearview windshield installed (slightly larger than stock), it pretty much topped out at around 230 km/h (about 140 MPH) true groundspeed, measured with GPS, on a level surface, no wind. For what it's worth, the front end was very light at those speeds, I don't think I would have wanted to go any faster.

Michael
 
paulcb said:
RPM to speed is linear, but the power to get to that RPM is not. I doubt any ST1100 can get to 150+ MPH without significant work.
Click to expand...

Thanks for explaining it better than I did. :thumb:

Case in point... that chart says at 8K it's doing 156. What is redline? If it's 9K then it would be doing 176 and I KNOW that ain't happening. LOL
 
Whooshka said:
Thanks for explaining it better than I did. :thumb:

Case in point... that chart says at 8K it's doing 156. What is redline? If it's 9K then it would be doing 176 and I KNOW that ain't happening. LOL
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The chart merely shows how fast the engine runs at various speeds. It's not an indication that you have sufficient engine power to actually reach those speeds. If you are on a steep downhill, you may reach 150 mph (~8000 RPM), if you are going uphill you may only have enough power to reach 100 mph (~5000 RPM). Very few bikes are designed to be able to redline in the highest gear...
 
CYYJ said:
Agreed. Back when my ST 1100 was new, I spent quite a bit of time riding around at high speed on the German autobahns. With a Clearview windshield installed (slightly larger than stock), it pretty much topped out at around 230 km/h (about 140 MPH) true groundspeed, measured with GPS, on a level surface, no wind. For what it's worth, the front end was very light at those speeds, I don't think I would have wanted to go any faster.

Michael
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ST 1100 can get up to 140 mph true speed. That is impressive. With less HP and more weight than the st 1300. I doubt if the st1300 can do better than 145 true speed.
 
My 1991 SSMST1100 has an aerodynamic threshold of 128.4mph (Zumo). TeSTed a couple of times (10 years apart) and for a sustained period of time. That’s with a number of drag inducing farkles installed. Had some rpms left, just couldn’t use them. FWIW

John
 
I made up a gearing comparison spreadsheet and calculated the speed/rpm for the 1100 and 1300; the overall ratio in top gear (including primary and final) is 4.03 for the 1100 and 3.93 for the 1300.
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Interesting chart.
The end gear ratio of the 1100 is higher than the end gear ratio of the 1300 yet, for any given engine RPM, the 1100's road speed is higher than the 1300.
The influence of the different tire sizes is rather significant.
 
Mine reads 4K Rpm's at an indicated 75 mph. Did wind it out one time to an indicated 130mph. I was too afraid to look at the tach so did not know the rpms. One more thing I've heard that the speedometers read about 5 mph's more than actual speed.
 
Larry Fine said:
The deficit is linear, meaning it's a constant percentage off. The faster you're going, the greater the error.
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I can see that being our ST1100's have a mechanical speedometer. Wonder if the digital ones like the ST1300 are more spot on?
 
red one said:
I can see that being our ST1100's have a mechanical speedometer.?
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Mechanical or electronic the same logic should apply. If the speedometer is off by 5% at 40 MPH it is most likely off by about the same 5% at 80 MPH. Even though the numerical difference is bigger the percentage deviation remains roughly the same.
red one said:
Wonder if the digital ones like the ST1300 are more spot on?
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No they are not unless you have a police model of an ST1300 or a speedometer off of an ST1300 police model. They are quite accurate.
Most owners whose ST1300 is equipped with a civilian version speedometer report that their speedometer reads in the range of 7 or 8% higher than actual speed.
 
TerryS said:
I made up a gearing comparison spreadsheet and calculated the speed/rpm for the 1100 and 1300
Click to expand...
Nice work. When I get a different bike one of the very few metrics I'm interested in is mph@4Krpm. That's very close to every larger displacement Honda I've ever owned which was/is ~71mph@4Krpm. I wish it were 78mph as indicated by your chart for the 1100.

Andrew Shadow said:
Most owners whose ST1300 is equipped with a civilian version speedometer report that their speedometer reads in the range of 7 or 8% higher than actual speed.
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That's my experience too.
 
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