Chainring bolts – super size me, please!

Preamble

Trying to fit a bash board, with the proper clearance and all three rings on a FC-MC36 or FC-M737, FC-M739.

Links

• Will a bashboard and 3 chainrings require longer bolts?
• Chainring Bolts guide

The bashboard currently on a FC-MC36, from SHIMANO crankset Fc-mc33 Fc-mc36 Welgo Pedals

Example of poor clearance on a M737 from eBay, XXXXLink

Points of note

1. The BCD needs to be the same. The Bashboard is currently ona MC36 and the BCD of that is 94 – which is the same as the FC-M737/9
2. Chainring bolts appear to be 10 mm generally. From the photos it can be seen that the bolts currently holding the bashboard are not fully inside the female threads, thus suggesting that they are already too short. At a guess:
   1. 13 mm are required.
   2. Adding another ring would mean 16.
   3. Adding a spacer to ensure the correct chain clearance from outer ring to the bash board would push this up to 20 mm.