Chainring Size Gauge for Shimano / SRAM

I put this up to have an easy way of checking whats the max chainring size for my bike frame without having to buy several sprockets in advance. 

Note that the Chainring sizes are rough measurements and might vary to the real deal depending on tooth shape. Although i made it a bit on the bigger side for each size, always take 1-2mm buffer into consideration when taking your measurement - just to make shure nothing rubs under full load when the frame might flex slightly! In my experience if the Gauge hits just slightly with the very edge you are still fine with an actual Chainring as long as the bike is static but the chainring will come really close to hitting the chainstay when pedaling. 

This guide works for oval chainrings aswell - as a rule of thumb oval chainrings are one size bigger than their round counterfits. One example: If the Guide shows a 30T round chainring fits, you should also be able to fit a oval chainring with 28T. Of course this hardly depends on how extreme the involute shape is done on your perticular oval Chainring!

All variants are done in 3mm thickness just to provide enough “wiggle room” so they will fit on the crank and still can be spun to position independently. Also printing is easier that way ;). 

Let me know about your experiences using it and if you need any other sizes / cranks. 

Im happy to provide updates to this in the future!

Currently available Gauges:

Shimano DM in 0mm and 3mm Offset

SRAM GXP (3-Bolt) DM in 0mm and 3mm Offset

SRAM QUARQ / Transmission (8-Bolt) DM in 0mm and 3mm Offset