RPM vs MPH?

[Jeffd]

I can't find the gearing calculator that shows what actual speed is at actual rpms. Say hypothetically that you could turn 4500-4600 RPM on a new Roadglide in 6th gear what would the actual speed be?  Rumor has it speedometer would show 120 but am thinking closer to 110 would be actual.

[ThumperDeuce]

http://www.rbracing-rsr.com/gearspeed.html

[05FLHTC]

http://www.bigboyzheadporting.com/Gearratio.htm

[Admiral Akbar]

Rumor has it speedometer would show 120 but am thinking closer to 110 would be actual.

Probably depends on the actual diameter of the rear tire and to how many decimal places the calcs were done at...

Max

[Jeffd]

according to both should be around 117 if in fact the rear tire is 25.2.  Seems pretty fast considering 4500 rpm in 6th gear was attained in a short distance hypothetically speaking of course.  Faster then what I would have guessed anyway.

[bladerunner]

http://www.gearingcommander.com/               I like this one .  ..............bladerunner

[Hillside Motorcycle]

BUT, you have to have one hellava engine, to aggressively pull to north of 6200 in 6th.
Just sayin'.
Scott

[oldguy]

BUT, you have to have one hellava engine, to aggressively pull to north of 6200 in 6th.
Just sayin'.
Scott

AND some brass b**** to be hangin on at 160+ mph when you get there!!

[Jeffd]

BUT, you have to have one hellava engine, to aggressively pull to north of 6200 in 6th.
Just sayin'.
Scott

i am suprised how fast a stock stage 1 pulled to 4500-4600 in 6th.  My guess it was going to hit a brick wall from that point on.  the RG fairing must be pretty aerodynamic compared to the batwing.

[Jeffd]

Thumperdeuce, o5flhtc and Bladerunner, thanks those are what I was looking for.  I especially like the one Bladerunner had.

[03deuce]

Jeff,
Was your speedometer pretty accurate at that rpm in 6th gear?

[04 SE Deuce]

  The speedo's are known to be optimistic.  What about verifying the tach/calc. with a GPS.  Even if you just put it in your pocket the max speed will be recorded.   Rick

[Jeffd]

Jeff,
Was your speedometer pretty accurate at that rpm in 6th gear?

Hypothetically of course.  The speedo needle sat right on 120mph and the tach was between 4500 and 4600.  It appeared as if once the needle hit 120 it stopped and the tach needle continued to climb a bit after that.  I have heard of people burying the needle but it seemed like the needle was at the end of its range of motion.  Any body run one on a dyno that can say for sure if the needle will keep going past 120 or do they stop?  If they keep going I would say compared to the calculator that bladerunner provided the speedo is pretty accurate up that high but my common sense (or lack of) says that does not make sense.

[04 SE Deuce]

  Have seen the speedo stop at 120 even though bike continued to go gain speed......don't believe this one was running 120 when the needle stopped as it is off 3-4 mph at 75-80mph.   Rick

[06roadglide]

I've verified my speedo is correct now after some adjusting with the TTS.  My speedo stops at 120 on my RG but keeps gaining speed.  I figure I've been to about 130 on it before easing out of it, I won't push a tire past it's speed rating. 

[02roadcling]

When I did the Beartooth a year ago I did 1 past 120 shortly after leaving with Scurvy heading east. My odo is dead nuts on every check and so is my speedo. It was still able to climb but traffic slowed to 85, lol.

cling

[TXChop]

I've verified my speedo is correct now after some adjusting with the TTS.  My speedo stops at 120 on my RG but keeps gaining speed.  I figure I've been to about 130 on it before easing out of it, I won't push a tire past it's speed rating.

Good point.. I got v rated tires coming.. Had my speedo buried on my bike a few times as well.Simple to do, but my balls run out about there. But since my last run, i have done rear ohlins, front raceteks, and a bagger brace..We'll see what it does when my tires show up. 

[beaureed445]

I was riding with a buddy once, and we both buried our speedos.  I was too busy hanging on, but he said that his was buried when I went blowing by him.  I don't know how fast I was actually going.  I've seen my tuner hit 135-137 on the drum with it, though.

[PoorUB]

Jeff,
Was your speedometer pretty accurate at that rpm in 6th gear?

Hypothetically of course.  The speedo needle sat right on 120mph and the tach was between 4500 and 4600.  It appeared as if once the needle hit 120 it stopped and the tach needle continued to climb a bit after that.  I have heard of people burying the needle but it seemed like the needle was at the end of its range of motion.  Any body run one on a dyno that can say for sure if the needle will keep going past 120 or do they stop?  If they keep going I would say compared to the calculator that bladerunner provided the speedo is pretty accurate up that high but my common sense (or lack of) says that does not make sense.

Riding my '05 Ultra I had the needle to the lower corner of the odometer readout. how ever fast that it. I varified the speedometer at 100 MPH once with my GPS. The speedo read about 6 MPH fast, GPS said 94'ish, speedo was at 100 so it works out to about 6% fast.

[wolf_59]

Here is one that I got off this site (may have been the old site) that I like to use

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