Little Fritz got a new mountain bike. Like just about any new dérailleur equipped bicycle, this bicycle comes equipped with a spoke protector, aka a frisbee or "dork disk."
The purpose of the spoke protector is to keep the chain from getting shifted off of the largest cog into the spokes. A properly adjusted dérailleur won't derail the chain into the spokes -- hence the name "dork disk," because presumably dorks don't have properly adjusted dérailleurs.
I'm pretty sure 13 year old boys don't worry too much about the adjustment of their dérailleurs either, in spite of the best efforts of their fathers. I know first hand the damage that can occur when a chain gets shifted into the rear wheel. The damage can easily run into hundreds of dollars.
What do you think? Should I hope and pray my son will always keep his bike well maintained? Or should I prepare for the worst and assume Little Fritz will be about as consistent on his bike maintenance as any other 13 year old?
Should the dork disk stay or should it go?
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I really dislike the 'dork disks' but I remember my own battles with my father over what should and should not be on my bike. I say let him decide what he wants to do.
Pie plates don't work any better than the federally-mandated "safety" devices do. They'll protect from some degree of misalignment, but they can be circumvented by any number of common situations, including simply repeated overshifts of a misadjusted derailleur. The disk may wear through or break loose. Stay? Go? "Amputation not necessary. In two week, it fall off."
My roadie (1976 Raleigh Supercourse) had the plate on it when I got it a couple years back and I don't see much reason to remove it "just because". It's not all that obvious except to the overly image-conscious. The time/effort that goes into removing one is better spent elsewhere. I only remove them when they break and start flaking.
If it's his bike, then let him decide what makes him feel best. If it's actually "your" bike, then do what makes you feel best. But, if you take it off, put it away nicely. Points off for a restoration without original "dork disk." Honestly, he's 13. He should learn good maintenance, but I hope he rides it into the ground, not caring what it looks like, knowing what's important is him, not the bike, and loves every minute!
He's a kid, Fritz. Of course he'll abuse the bike. I say leave it in place. If he objects, let him learn how to remove it, and more importantly, let him learn how to keep the derailleur adjusted and aligned. It's almost a given that he'll drop the bike on its right side at least once, perhaps bending the derailleur inward.
Wow! I can't believe no one knows the coolest name for that part ever: the "cosmic ray deflector"!
As a mechanic, I can say that most likely will not make much difference whether it is on or off. However; I will say that it wouldn't hurt in the case of a kid to leave it on. A right side dump, common with kids when they don't use a kickstand, or prop up the bike, will likely bend that hangar inward and you know whaere that will lead!