And I mean I speed and I need help, I actually enjoy it

I have just put on a 14t front sprocket and a 42 rear sprocket, and obviously this is going to ruin my speedo, so what I want to know can someone give me some kind of calculation so I can figure out my Real speed, cheers.

you got a sat nav?

There you go
http://www.gearingcommander.com/

Drunkn Munky wrote:There you go
http://www.gearingcommander.com/

I have seen this,

im more after the % of difference the speedo will be out by so I can get a good reading.

I took it for a blip earlier and was reading 120km and im positive it was only about 90

Your never have time to work out percentages whilst riding, plus it'll be different for each gear your in. Just get some form of GPS speedo, a digital one or just dont worry about it.

Drunkn Munky wrote:Your never have time to work out percentages whilst riding, plus it'll be different for each gear your in. Just get some form of GPS speedo, a digital one or just dont worry about it.

Haha yah, I think the last time I actually done the speed limit was when I had stopped after been pulled over by the police..

Another suggestion:

Did you realise the little elbow gearbox in the back of the speedo can be used to alter the speedo calibration? Here's a picture of the inside of a cb-1 speedo to illustrate my point.


The yellow plastic gear on the back of this km/h speedo has 12 teeth. The matching yellow gear in the elbow has 11 teeth. Equivalent MPH speedos have 12:12 green plastic cogs. The reason is the km/h speedo comes from a JP bike which were sold with 15/41 gearing, while the mph speedo comes from a USA bike which were sold with 15/37 gearing. Changing these parts gives about a 9% reduction in speedo reading when compared with equivalent green-toothed parts, matching the regearing of the final ratio fairly closely.

It's not a very precise calibration, but the option is there. I have a spare gearbox with yellow 11:12 gears. I have no clue what's in an nc30, but if 11:12 is any use, then give me a shout. I find myself wondering what the equivalent conversion rates would be on any number of Hondas which use the same speedo, I am sure the same system was used on early Blades, many CBR600s, etc. etc.

Hope that makes sense and maybe helps!

amorti wrote:Another suggestion:

Did you realise the little elbow gearbox in the back of the speedo can be used to alter the speedo calibration? Here's a picture of the inside of a cb-1 speedo to illustrate my point.


The yellow gear on the back of this km/h speedo has 12 teeth. The matching yellow gear in the elbow has 11 teeth. This gives about a 9% reduction in speedo reading when compared with equivalent green-toothed parts from a mph speedo which have 12:12 teeth. The reason is the km/h speedo comes from a JP bike which were sold with 15/41 gearing, while the mph speedo comes from a USA bike which were sold with 15/37 gearing.

It's not a very precise calibration, but the option is there. I have a spare gearbox with yellow 11:12 gears. I have no clue what's in an nc30, but if 11:12 is any use, then give me a shout.

Hope that makes sense and maybe helps!

makes alot of sense actually, according to what you said I should have a 11:12, I have a straight Jap import in Km/h.
Ill have a look about, I may just end up getting my hands on someone GPS, I only need to know my read speed at 50km/h and the dial speed at that speed to work out a % of how far + or - the speedo is, then it should be the same % across the dial, all I have to do is put some markers on my speed so I know. 50 - 70 - 100km are the important numbers as 50km is the limit around town, and 70 is the limit on the road I have to take to get back home etc, and 100 for the open road.

In going from 15:40 to 14::42 you have done this:
(14:42) x (15:40) = 1/8 , so your speedo will be over-reading about +12.5%. That is, about 12.5% more than it was before, since we all know [bike] speedos over-read anyway.

The 11:12 gearbox will subtract 1/11 or 9.1% off your speedo reading, if yours normally has 12:12 gearing.

DrunkenMistake wrote:makes alot of sense actually, according to what you said I should have a 11:12, I have a straight Jap import in Km/h.
Ill have a look about, I may just end up getting my hands on someone GPS, I only need to know my read speed at 50km/h and the dial speed at that speed to work out a % of how far + or - the speedo is, then it should be the same % across the dial, all I have to do is put some markers on my speed so I know. 50 - 70 - 100km are the important numbers as 50km is the limit around town, and 70 is the limit on the road I have to take to get back home etc, and 100 for the open road.

My information is based solely on my research of CB-1s, I know nothing about nc30's! Have a look at the gearbox in your speedo and report back.