Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[cahdbiker]

Hi Guys, I was on my favorite "getting it on road" called Las Posas Rd in Ventura County. I was wondering if anyone could tell me what my RPM was at 112MPH in 5th gear. I forgot to take a note of it since I was concentrating on the road in front of me. Las Posas Rd is great for a speed run because it is flat without any peripheral foliage. The only issue is the farm workers who park along the side of the road. Natually I was not going 112MPH where they were working. If you google Las Posas Rd. in Ventura County Ca. and scan towards the ocean you will see Pt. Mugu . The bolder there is in the picture of my bike below. The car companies love that stretch of highway for commercials so you have probably all seen it at one time or another. Anyways back to my question if someone knows what RPM I was doing when I hit 112MPH in 5th I would like to know. All the gearing on my 09 is stock. Thanks in advance. CAHDBIKER

[JCZ]

Not sure what the rpm is at that speed.  Is this the first time you've gone that fast?

I know where Pt. Magoo is, been by it a number of times but have never saw it on car commercials.  Down here all we see is the Coronado Bridge in the local car commercials.  Car commercials are done locally.

Hope you two are able to make it up to the Redwoods Run......3 1/2 months! 

[Cat Eye]

If I recall 5th gear is a 1 to 1 ratio....if so then just check to see what your rpm is at 56 mph then just double it.

[Dan_Lockwood]

If I recall 5th gear is a 1 to 1 ratio....if so then just check to see what your rpm is at 56 mph then just double it.

Cat Eye:

Cruise Drive 6-speeds have 6th gear as 1:1, not 5th.


cahdbiker:

The rpms at 112 mph:

24.5" rear tire= 5069 rpms
25" rear tire= 4967 rpms
25.5" rear tire=4870

I'm guessing our rear tires are around 24.5", but not sure.

Our final drive ratio in 5th gear is 3.279 and in 6th gear it's 2.79.

Hope this helps you out.

[grc]

How was the 112 mph determined?  If from the Harley speedometer, and it hasn't been recalibrated, figure at least a 5% error so the 112 becomes approximately 106.  If from a stand alone GPS (not the built in version on the Rushed More bikes), the speed reading from the GPS will be much more accurate than the speedometer.

While 5th isn't 1:1, Cat Eye was on the right track if you just want an approximation.  Ride the bike at 56 mph in 5th gear, note the rpms, and then multiply by 2 for the rpms at 112 mph.  The relationship between speed and rpm is linear.

Jerry

[JCZ]

That's a whole nother issue Jerry.  And isn't it progressive error?  I mean at 80 mph you might only be a couple miles an hour off but above a hundred miles an hour you're going to be further off?

There's a whole thread on this HD phenomenon a few years back.  The HD speedometers are right in line with all the other HD gauges, etc. with the attitude of "close is good enough".   

[grc]

That's a whole nother issue Jerry.  And isn't it progressive error?  I mean at 80 mph you might only be a couple miles an hour off but above a hundred miles an hour you're going to be further off?

There's a whole thread on this HD phenomenon a few years back.  The HD speedometers are right in line with all the other HD gauges, etc. with the attitude of "close is good enough".   

That's why I mentioned a percentage error, not a set number of mph.  5% at 70 mph is about 3.5 mph, but that same 5% at 120 mph would be about 6 mph.  Many are worse than that, some better.  Usually, but not always, speedometer error in actual mph increases as speeds increase.  Thus you can't really just tell people your speedometer is about X mph fast without qualifying that by saying X mph fast at YY mph.  It's better to express it as "approximately X% fast".

Yes, Harley's gauges all leave a lot to be desired.  I still say most of them are useless and were just included to fill up the holes Harley had molded into the fairing.  As cheap as the ones they use are, it would have cost more to retool the fairing to eliminate the holes than it cost to buy and install the gauges.    It actually made perfect sense a few years back when they eliminated two of them and filled the holes with tweeters.

Jerry

[Rooster]

I use the speed on my GPS at 60 and above seems about 3 mph faster reading on the HD Speedo or reads 3mph lower on the GPS versus the HD Speedo. That hurts my head thinking about it.

[VANAMAL]

Jc hits the rev limiter in 6 th gear

[JCZ]

Jc hits the rev limiter in 6 th gear

So what was the rpms when I did that? 

[VANAMAL]

i got new tires I'll take mine out this weekend and find out

[cahdbiker]

Good to know ThanksCAHDBIKER

Cat Eye:

Cruise Drive 6-speeds have 6th gear as 1:1, not 5th.


cahdbiker:

The rpms at 112 mph:

24.5" rear tire= 5069 rpms
25" rear tire= 4967 rpms
25.5" rear tire=4870

I'm guessing our rear tires are around 24.5", but not sure.

Our final drive ratio in 5th gear is 3.279 and in 6th gear it's 2.79.

Hope this helps you out.

[cahdbiker]

JCZ, regarding your post, on this bike it is the first time to hit approx. 112.  When my bike was completely stock I hit 105 up hill passing a 30 ft. fifth wheel pulled by a Ford Triton Dually. I was coming out of Casper Wyoming heading west towards Riverton. Had my wife on the back and luggage. A lady in a Blazer was kind enough to pass over a double line and head straight at us. So I gave her the 180 degree  finger while still in 5th going up hill at approx. 105MPH . Proceeded to shift into 6th and held it at 100 for at least 3 miles. The only time I have gone faster then that was in a few cars I have had. Feels great!!! If I can get some info on the REDWOOD RUN I will try and make it since my wife is from that area. What I like about this site is that you can pretty much get any info you need, and if you say something that is incorrect people will correct you in a diplomatic fashion. Thanks CAHDBIKER

Not sure what the rpm is at that speed.  Is this the first time you've gone that fast?

I know where Pt. Magoo is, been by it a number of times but have never saw it on car commercials.  Down here all we see is the Coronado Bridge in the local car commercials.  Car commercials are done locally.

Hope you two are able to make it up to the Redwoods Run......3 1/2 months! 

[RonandJanet]

I have not taken mine much past 100 MPH (just enough to know I did it).  I do cruise at 75 and 80 all the time!  The gauges may not be perfect but it is also hard to get an exact reading on it. I do like the GPS readings better. I know she read a little high before but when the dealer replaced the bad one (it would not go back to 0 stayed at something like 4 MPH) the new was much better. I used the GPS and my wife's car to compare I was rarely off 2 miles an hour (tried this at 50 and 70).  I know this isn't exact either I was just making sure I was in the ball park.  I would not be surprised if the gauges on all my vehicles are not perfect. Hell I am not perfect so my girl and I will just cruise at whatever speed we feel comfortable with!       

[VANAMAL]

This was in a 55 mph zone. I told the cops my name was jc