Removing chainring bolts - any hints?

bompington

I'm replacing the big ring: standard SRAM Rival that came with the bike. It's clearly held on by normal looking hex bolts, but when I try to undo them, I can only ever get the Allen key to engage on one side at a time.
Any clues?

pilot_pete

If they are Allen head both sides then one should be bigger than the other. Put the big one in first and the the smaller one as the big one shouldn't go all the way through.

If it is Allen head on the outside but has a slot on the back then the Allen head is just the 'bolt' head. The 'nut' on the back requires a special tool or a big flat blade screwdriver or similar to stop it turning as you undo the Allen head bolt with your hex wrench.

Here is the tool http://www.chainreactioncycles.com/park-tool-chainring-nut-wrench-cnw2/rp-prod14305?gs=1&gclid=CMy1ieOxxM8CFREUGwodudkMFQ&gclsrc=aw.ds

PP

keezx

Front side= 5 mm hex.
Back side = 6 mm hex.