How to count teeth on rear sprocket ?? (serious question:) )

[Dave7]

A friend wishes to change his bike's rear sprocket and I have told him to count the teeth on the smallest & largest cog (and all in between if he can) so as to find out what is possible.
I am just wondering if there is an easy/obvious way of doing this and be certain you haven't 'missed one' or counted one twice.

 

[Profpointy]

tipex

and remember if you've already counted it when you get back to that tooth

 

[ianrauk]

Wipe the grime off one of the teeth...

 

[Dave7]

tipex

and remember if you've already counted it when you get back to that tooth

Great..........that is the sort of obvious method I thought would be there if my brain worked.

 

[Deleted member 23692]

Have a look to see if the number of teeth are stamped on the sprockets

 

[Saluki]

Wipe the grime off one of the teeth...

That's what I do but my Dad always used a little drop of tippex (or Snopake as he called it)

 

[snorri]

Wipe the grime off one of the teeth...

Perhaps Dave7s friend keeps his bike as scrupulously clean as yours ??

 

[gavroche]

Start with number 1 then 2, 3 so on.

 

[Profpointy]

Start with number 1 then 2, 3 so on.

For best accuracy go round three time and divide your answer by three to get a statistically valid average

 

[MichaelW2]

Count each high and low point and divide by 2.

 

[Profpointy]

Perhaps Dave7s friend keeps his bike as scrupulously clean as yours ??

then you just put some muck on tooth 1 (or was that tooth zero?)

 

[helston90]

Take it off the wheel, trace around it on a piece of a paper and number the peaks. Simples.

 

[Yellow Saddle]

Measure the circumference of the sprocket and then divide it by one half 1/2 inch.

This answer was inspired by Niels Bohr's method of calculating the height of a building using a barometer.

Edit: I've been inundated with zero private mails from people (NOT) noting the flaw in my method. The circumference has to be measured not at the outside of the sprocket but at a point exactly half the height of the teeth.

 

[young Ed]

Perhaps Dave7s friend keeps his bike as scrupulously clean as yours ??

well unless @ianrauk has cleaned it then i reckon there's no chance of that!
Cheers Ed

 

[jowwy]

Keep your index finger of your left hand on tooth 1, while using the index finger of your right hand to count the others