Measuring chainwheels / spiders

[highrisedrifter]

Hi there

I recently bought a chainring and a spider to go wth it. However, it seems that the diameter of the spider is too big for the chainring



Can anyone tell me from where to where they are both measured, so that I don't make the same mistake again, please?

Thanks

HRD

[MartyC]

I believe that you measure from one hole to the second hole along, almost diagonally if that makes sense 

What you have there is a Sugino Ring with a Takagi spider 

[Coastvl]

Shimano, Takagi and Sugino +whatever else are different spacings obviously.
The Takagi and Shimano sprockets are noticably bigger than the sugino and some others. I can't tell you how to measure them but they are very noticable when you look at them. Your sprocket looks like a Sugino size and the spider is a Takagi.
Most people use the names to distinguish the sizes.

[MartyC]

Sugino use 110mm bcd and Takagi 130mm bcd 

Updated to 130mm as per the Taffy Geordie 

[mark 2]

Damien, what you do is......it's called the bolt circle dimension. It's as if there is an imaginary circle running through the centre of the holes and you measure it across. On the chainring you've got in the picture it's 110mm but the spiders 130mm. Sugino's and Suntour chainrings are 110mm, Takagi, Tioga and Shimano are 130mm, some have both like Tuf Neck's.......

[highrisedrifter]

Thanks for the help everyone, with the possibly exception of the non sequitur from 69 there. 

So the chainring I have is 110mm and the spider is 130mm.

It makes sense now. Many thanks.

HRD

[69]

old skool,do the monster stomp

[highrisedrifter]

old skool,do the monster stomp

In the quiet words of the Virgin Mary... come again?

[69]

LIKE A BAD SMELL

[lazychubs]

lucy did ask me if the spider would fit and said yeah as didnt know they came in two sizes

[highrisedrifter]

No worries mate. I need another one anyway for another build so it's not a problem. 

HRD