Adventure Bike Rider Forum

Not the chain, but a rear sproket??
The chain I don`t need to do, it's a 520. But I need to check the pitch of the rear sprocket 45 teeth

Any ideas?

Cheers

how do you mean, the pitch, 520 or the teeth?

the pitch of a standard #520 chain is 5/8", to fit on a 1/4" wide sprocket. to know the number of teeth, count the teeth!
its usually stamped on the sprocket side but also usually covered in filth

It`s a 45 tooth rear sprocket
I need to check that it is for a 520 chain.
It came as a pair. Front & rear obviously. The front is definatly NOT a 520 pitch as it doesn't fit the brand new 520 chain I have. So I need to confirm that the rear sproket is for a 520 chain.

If you follow all that..

On the sprocket you will need to measure at a point in the centre of the radius at the bottom of where the chain roller sits to the same point two further radii along.

So that's in the first radius , miss one, then at the third one are your points of reference and then divide this figure by 2.
For a 520 (5/8 pitch) to fit your sprocket this distance should be 1.25"

What is the (precise) thickness of your sprocket?

Thanks....I'll do it on the morning and let you know. Gives me an excuse to use my new digital vernier gauge....happy days!!

OK...distance between the radius is 30mm
Thickness is 6.4mm

my maths is shite, but doesn`t that work out about right 1.25" = 31.75mm???

exrm193 wrote:OK...distance between the radius is 30mm
Thickness is 6.4mm

my maths is shite, but doesn`t that work out about right 1.25" = 31.75mm???

Having something work out 'about right' isn't the same as it being right. Perhaps you weren't quite so accurate with your measurement because at 30mm you will be a long way out after a full revolution of your sprocket.

I am surprised you have a 6.4mm thickness of the sprocket as opposed to either 5.7 or 7.2mm . I'm not entirely sure that a 6.4 actually exists!

Deffo 6.4 mm....brand new digital vernier gauge :laugh:
Again Definatly 30mm between the bottom of the U bit of the sprocket.

The front is certainly NOT a 520. I just need to know if the rear is the same. I rang the supplier & he double checked the part number saying it was a 520. But I went in and showed him it with my chain & it Don`t fit.....DOH!!

A 520 chain has a roller width of 1/4" (.250) therefore the sprocket cannot be the same as it would then be an interference fit, which in turn would put unnecessary loadings on the g/box as well as sapping horsepower!

Are you measuring the thickness at where the chain rolls over the sprocket or somewhere else on the sprocket?

right down the centre of one of the teeth