Configuring Speedometer

[tmakt]

I bought and installed:

LCD Bike Bicycle Cycle Computer Odometer Speedometer NR - eBay (item 180402633718 end time Jan-28-10 11:20:59 PST)

Now when it asks me for my tire size the range is 60mm to 229mm

I did the roll out on the bike and measured 44 inches.

After doing some converions, its just not adding up right.

What am I doing wrong?

 

[Strigoi]

that does seem small. 229mm is just a hair over 9".

 

[tmakt]

so this speedometer is useless?

 

[tmakt]

Oh, btw

my tire size is both front and rear are 145/70-6

knobby style

 

[joekd]

That cant be right, a 26" wheel (common bike size) is 660 MM

60mm=2.3", how the hell can you put a speedo on a bike with a 2.3" wheel?

 

[tmakt]

:censure: damnit!! :doah: lol

i just looked at it in detail for the 10th time and it says 'CENTIMETERS' not mm...

that should skew things a bit, eh?

 

[tmakt]

ok so like i said earlier, with my 145/70-6 tire size on both wheels, i did the roll out method to measure the circumfirence. i just put some paste in the middle of the tire on one of the "knobs". and rolled forward with me sitting on it. I measured the two points on the ground and its ~44 INCH.

Now google convert

44 inch = 111.76 centimeters

which is much more appealing and within range.

One more question regarding this issue, do those numbers now look about right for my tire size?

 

[vette66_00]

ok so like i said earlier, with my 145/70-6 tire size on both wheels, i did the roll out method to measure the circumfirence. i just put some paste in the middle of the tire on one of the "knobs". and rolled forward with me sitting on it. I measured the two points on the ground and its ~44 INCH.

Now google convert

44 inch = 111.76 centimeters

which is much more appealing and within range.

One more question regarding this issue, do those numbers now look about right for my tire size?

I think it wants you tire height not roll distance.

 

[tmakt]

Is that so?

 

[vette66_00]

Nah I think your right. Try it out. Put what you got and see what your speed is. Get somebody to run next to you in a car and then you can tell....or a GPS unit. You can adjust it to make it more accurate.

 

[Riley]

at walmart they sell good quality ones like that, but with more features like a clock and stuff... only 15 dolalrs

they give really easy instructions on how to calculate it

 

[krakerjak]

:censure: damnit!! :doah: lol

i just looked at it in detail for the 10th time and it says 'CENTIMETERS' not mm...

that should skew things a bit, eh?

 

[krakerjak]

Ive been saving that one just for you tmak

ok so like i said earlier, with my 145/70-6 tire size on both wheels, i did the roll out method to measure the circumfirence. i just put some paste in the middle of the tire on one of the "knobs". and rolled forward with me sitting on it. I measured the two points on the ground and its ~44 INCH.

Now google convert

44 inch = 111.76 centimeters

which is much more appealing and within range.

One more question regarding this issue, do those numbers now look about right for my tire size?

yes 111.76 i correct, you could of just taken the tire size " 14 inch diameter " off the baja site. then X by 3.14 = ~44 then covert it to cm to get the 111.76, and all this was done from the sh**er while you are playing with paste in the cold.

 

[tmakt]

Dont you dare embarass me in front of my friends again! :gun_bandana:

 

[tmakt]

Ok so after setting it to 111cm:

I weigh something like 190-200 no more no less.
The max speed recorded was 32 MPH on a 12t/70t setup with throttle limiter screw removed(6.5 HF). Tomorrow we will confirm with a GPS unit.

Does this top speed seem right? Not sure how others weighing 180 ish with stock motors hit 40-45 ??? 20lbs right makes that much difference?

 

[vette66_00]

Ok so after setting it to 111cm:

I weigh something like 190-200 no more no less.
The max speed recorded was 32 MPH on a 12t/70t setup with throttle limiter screw removed(6.5 HF). Tomorrow we will confirm with a GPS unit.

Does this top speed seem right? Not sure how others weighing 180 ish with stock motors hit 40-45 ??? 20lbs right makes that much difference?

Weight only has to do with rolling resistance 20 lbs is not going to be that much. 32mph on a governed motor seems kinda high. I got mine to 42 ungoverned with stock intake and a pos header and I weight 230lbs. Now Im sure it's higher with current mods.

Of course this is with a 6.5hp clone. If you have a stock motor 32 mph is about the fastest you will get it and it takes 4ever.

 

[Strigoi]

Not sure how others weighing 180 ish with stock motors hit 40-45 ???

40mph is around 5500rpm on a DB with a 12/70 setup. that's doable with a billet rod and 18lb springs and otherwise stock 6.5.

confirm your speed with the GPS and then use one of the calculators in the sticky thread in the General section. if you know your gearing, tire size and speed you can figure out the rpm.