Topic: Why do guys only ride with a TACH???

[JAG]

Maybe this is a dumb question, but I gotta know.

Why do some of you guys only ride with a tach. Why not both tach and speedometer? I'm sure if you're in the city you can just flow with traffic, but how the heck do ya know how fast you are going? What if a cop pulls up behind you and rides your ass like they do down here. I just see a lot more cons than pros with only running a tach..

Bear in mind this is pure speculation, and just mere curiosity.. I've seen some sweet set ups, needles pointing down and all..

I guess I just dont get it..

Amuse me

[mystic_1]

Tach-only is a racer look, I think.

You can of course compute speed versus RPM for any given gear, so it's possible to tell about how fast you're going, but that'll always be approximate.

mystic_1

[JAG]

From what I've heard the Speedos can even be off 5 or 6 m.p.h.

So maybe either way it can be estimated

Is there a formula to this speed vs. rpms to equate it?

[BLUE71TURBO]

So they don't know how really slow thier motorcycle is !!    

[Gordon]

From what I've heard the Speedos can even be off 5 or 6 m.p.h.

It's normally off by a percentage of the indicated speed, not by a certain number of mph.  8-10% fast seems to be pretty common for a lot of the sohc4's. 

[BobbyR]

From what I've heard the Speedos can even be off 5 or 6 m.p.h.

It's normally off by a percentage of the indicated speed, not by a certain number of mph.  8-10% fast seems to be pretty common for a lot of the sohc4's. 

I hope that is true, it makes me feel bolder. 

[mgbgt89]

On my 350, using the tach is a more accurate way to judge the speed than the speedo. When my speedo shows 80, tach is about 9500 in top gear. Riding with 2 other bikes, a CBR and a sportster at that speed, They were both showing about 95mph.

I rode for a while without a working speedo, and every 1000 rpm in 5th i estimated to be about 10mph, which seems to be pretty accurate.

[bender01]

Because when they sell you that well cared for LOW mileage machine you will pay more money. A neighbor growing up used to do this with Subarus. They probably had 50k more miles on them than on the speedo. Crafty!

[jkot55]

You could bring a GPS with you once or twice just to note different speeds at different RPMs.  Do it for each gear at 2000, 3000, 4000 and that should give you a good pattern that will allow you to have a good idea of speed relative to tach position.  Just a thought.

[JAG]

You could bring a GPS with you once or twice just to note different speeds at different RPMs.  Do it for each gear at 2000, 3000, 4000 and that should give you a good pattern that will allow you to have a good idea of speed relative to tach position.  Just a thought.

Thats a good idea.. I was talking with volkswagendan about doing just that..

I guess once we start cafe'ing our bikes, and cutting stuff off the frame, miles aren't really important then.

The main thing I use off my speedo is my trip meter, cause thats how I gauge how many miles I've gone on a tank of gas..

I guess I could just strictly go off the petcock. So when it starts hesitating and running outta gas, flip to reserve and get to a gas station..

[1974CB750rider]

My speedo is exatley 10mph off. If I'm showing 65mph I'm really doing 55mph. I found this out by one of those speed monitor trailers that the cops set up on the side of the hwy. I went by it once and noticed what it said and looked down at my speedo then decided to turn around and try it again just to see how off my speedo is.

[754]

Stock geared 750 ...3000RPM =30 mph..in 3rd gear

                            6000 RPM = 60mph..in 3rd gear

 in 5th gear 4000 RPM = 60 mph

                 5000 RPM = 75 mph

                  6000 RPM = 90mph

 so it aint too hard to figure out..

 in 07 I rode to Bonneville with no speedo or tach.. just winged it..

[mystic_1]

I guess I could just strictly go off the petcock. So when it starts hesitating and running outta gas, flip to reserve and get to a gas station..

That works OK until you're riding two-up in the boonies on a Sunday evening when everything's closed, even the first two gas stations you come across. 

Ask me how I know this

mystic_1

[andy750]

Most modern bikes come from the factory with speedo off...take the VStrom for exmaple...well documented that its off after you get faster than 55 mph.

Only GPS is accurate....

cheers
Andy

[6adan]

I have been riding my 70 JDM sense new with a KPM speedo sense new and have only got one ticket and that was right after I got it. I just go with the flow.

[IHWillys]

I rode my XS650 for about ten years without a tachometer or speedometer.  I also drove my '55 Pontiac without a functioning speedo for many years and a largely inaccurate one in my '51 Willys wagon so perhaps I've been conditioned to "recognizing" the speed of ~60mph, ~45mph, ~30mph so I don't get speeding tickets.

I will add though, during those times while being followed by a cop, I wish I had a good speedo.

Ken

[dansvs]

If those guys are track riders or racers, the idea is to keep the rpm's up near the rev limiter for the most power available.
Street riding in this manner only seems to draw flashing lights for some reason.
I like to keep whatever bike I am riding at 60% of the available rpm's when on the street.

[BurtonWarpup]

I considered running with only a tach for looks purposes, but I don't want to lose my odometer.

[nippon]

Probably, because some guys don't like to get reminded how slow they are?

[Gorms]

I did it for asthetics.  Its mostly an around-town bike and I have an idea of how fast I am going.  Also, if you know what gear you are in, you can keep a mental note of the RPM and know how fast you are going.  I am also used to it from driving an old European sports car with the tach large in the center with e small speedo in KPH off to the side.

[754]

Cut up a broken speedo, make a small box for odometer, and mount to forkleg.. use a shortened cable.

 You can make a billet housing, with or without window, if recording mileage is a concern..