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XT 2008 crank

2K views 2 replies 3 participants last post by  Big_Ring 
#1 ·
I just recently bought a Giant Trance X2 with some upgraded components including the usual stuff and a new 2008 XT drive chain and shifters. When I had a random look at my crank I saw the teeth on the outer and middle chain rings were oddly shaped, some were pointy and some were shorter by about 2mm and had flat ends of the teeth. There isn’t a particular pattern to this and there is about twice as many pointy teeth as flat ones. So I was wondering if there is a reason or is it just sloppy workmanship.

This isn’t causing a problem when riding. The other cranks I have from Truvativ and RACE FACE all have pointy teeth.

I’m sorry if I’m being an idiot about something.:D
 
#2 ·
I just purchased the same crank and noticed the same thing. On past cranksets that were not Shimano some have had this problem and some not. It never affected the performance I think....although it seems the ones that had different shaped teeth were usually the ones that ended up getting broken off.
 
#3 ·
In fact, it does affect performance...

The difference in shape is to facilitate shifting. If you look at the inside of the big and middle chainring of a Shimano crank, you will see a lot of details that might look random. They are shifting ramps. They allow your chain to progressively go from one ring to the other (imagine a set of "steps" from the middle ring to the big one), making the shifting that much smoother. The difference in shape of the teeth is to allow the chain to slide easily in place at the end of those "steps".

no sloppy workmanship there! just brilliant engeneering...
 
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