Originally Posted by
FBinNY
Not faith, unless you mean faith in math.
No, faith in some random mechanic at some random shop that you've never met or worked with.
I'm just stating that my cousin's bike came back from a shop and the chain would drag in small-small. I removed two links to stop the dragging, no issues in big-big. The mechanic just threw the chain on, without measuring or removing links or anything. It was the standard 114 link chain, mounted as-is. I don't put a lot of faith in shop mechanics, this is just one example of why.
You are making an assumption. You are assuming that the mechanic would even use any math; talking about random mechanics here, not you or me.
Originally Posted by
HillRider
Yes, simple enough unless the chain is too short to allow big:big. If that's the case the problem won't be a slack chain, it will be broken parts if the unavailable gear combination is inadvertently used. So while a usable small: small is nice, a usable big:big is essential.
I don't disagree, but now we are getting into a scenario where the chainring and cog sizes are pushing the capacity of the rear derailleur when in small/small. Granted, at that point the rider is cross-shifting which should be avoided. To me, an ideal set up will allow small-small without running out of chain for big-big. When we cross that thresh-hold, the bike is no longer idiot-proof. The person riding absolutely MUST be aware of what combinations work and which won't (which is uncommon). Whatever the case, I was just laughing at the fact that @
Bill Kapaun referred to his method as "simple." The method is fine, but I'm not sure I'd call it simple.