I've never needed a wrench either till I changed the inner ring on my FSA chainset a couple of months ago, the buggers kept spinning without one.Oh, the actual chainring bolts - sorry, I thought you meant bolts for cranks ...
I have never had to use anything other than a finger to stop the threaded collar moving. An allen key in the bolt has always worked just fine for me. I hold the other side until the bolt has started to do up or when it starts to move when undoing the bolt.
Alternatively, I would use a 5p coin!After reading the reviews for tools to do the job I decided just to use a 5p coin & it worked a treat
I've never needed a wrench either till I changed the inner ring on my FSA chainset a couple of months ago, the buggers kept spinning without one.
Best type of wrench is this -
http://www.evanscycles.com/products/fwe/chainring-bolt-wrench-ec053207
Those flat things are hopeless and you'll need some Germoline for your knuckles after using one.