HELP! Chain rubbing on Front Derailler! - Page 2

Actually, I'm curious about this. The debate here -- seriousturtle's contention that severe chain angles can conrtibute to wear, and boudreaux's assesment of hooey -- is one I don't have an informed opinion on and I was wondering if you guys wanted to weigh in a little more.

It certainly seems that pulling the chain across gears in increasingly extreme angles would accelerate wear -- there's something intuitive to that claim. Boudreaux, what's your thinking? I'm openly acknowledging the value of your weathered cranium. Spill the beans, old man.

I'm not really sure why boudreaux threw down the "hooey" call on that one... I suspect it's because seriousturtle said that you shouldn't use the three small cogs in the rear with the small chainring up front. That's a bit excessive. I've always heard not to use just the smallest cog in back with the small chainring.

Anything other than a straight chainline does put a side load on the chain and also effects the efficiency of the drivetrain. Inefficiency and chain-stress increases as the angle of the chain increases. This does not however effect chain-wear in the traditional sense (increased pitch distance).

Me? I never worry about chain wear. At only $30 to $50, I don't really care whether it lasts for 2000 or as much as 6000 miles. So, I'll grind away for awhile in big/big or small/small if I am too lazy to shift (or in a hurry). I won't target those combos, though.

As for more wear in the first place, I'd guess that the racket it makes (much more in big/big than small/small) is in indicator of increased wear/friction.

I'd agree somewhat with you there... but as someone who has experienced a chain break in the boonies, I want to do what I can to ensure a long life. It's pretty easy to make it a habit to shift from small chainring to middle before you get to smallest/smallest. Same with biggest/biggest.

i was a former bike mechanic for awhile and the crossover angle was something i learned about. it's harder on the drive train as the angle is more extreme. granted, not life or death, but something i try to keep in mind. also, i mentioned not to go small chainring to the smaller 3 cogs. sorry, i was speaking from my bike, which has a triple, meaning the angle of the chain is super nasty at that combination. if you're using a double, i suspect that its only the smallest or two that you should probably avoid. also, try setting up the right cogs and chainrings with specific # of teeth that are best suited for you. hope that clears things up.

~the turtle