Hey there, I am planning on designing a bash guard to have CNC machined from 6061-T6 Aluminum at a local machine shop. I am currently in the design phase. The question that comes to mind is: How big does it need to be? My chainring is 180mm in diameter, so obviously, inorder for it to function properly It would need to be larger than that. would 190mm be too large? that would mean 5mm of distance from the outside of the bash guard to the outside of the chainring.

Remember that the od of the chain ring is increased when the chain is on it by a few mm. I have a custum bash ring and it is 10mm bigger then the od of the chain ring and is5mm thick. Works great.
Slainte

Just a thought: You might want to check these guys out first.
https://www.chainwheels.com/bashrings.htm

They have a number of different bash guards and also do custom work. Since they already have the experience, it might prevent you from making a costly design mistake. And since this is their business, you might get a better deal.

No affiliation, just thought I'd pass along the info.

hey thanks for the information. ya know i never even thought about the bash guard protecting the chain.

riderx: im gunna go check out the www you posted. thanks for the link.

Specialities-TA make a cyclo-cross bash-guard, two rings which fit each side of a single chainring. It stops derailment as well as protecting the rings and chain.

what I am looking for is a bash guard that will still enable me to use all three chain rings.

You can check out Evil Chainrings and comments by users here at at Ridemonkey https://www.ridemonkey.com/forums/sho...threadid=25323

I believe their system allows for use of the middle and small chainring, but not the big one!

Also MRP makes a system that allows for a 2 ring system. I believe their address is https://www.teamplanetx.com/mountainspeed.htm

If thats NOT what you're looking for, I know that you can order one that bolts onto the outside of the big ring, PM me and I'll get you the number of who to call!

L8R