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I'm thinking of buying a second hand Shimano FC-TY30.

However, looking at the photo there seems to be either worn or chipped teeth on the second ring1.

Gears of Shimano FC-TY30 chainset

Are they actually broken/chipped, or is that by design, for changing gear? Even though I'm not an expert on gear technology, they don't seem even spaced, if they are intentional.


1 At about 9 o'clock, at five teeth clockwise to around 10 o'clock, at half past two and at about 4 o'clock.

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    Looks fairly normal to me -- the "ramps" on an indexed system. They are spaced with regard to the pedal rotation. Overall there appears to be some wear on the rings, but nothing exceptional. – Daniel R Hicks Aug 25 '18 at 17:59
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    Different sizes are intentional to assist shifting. The smaller ring looks well used while the big ring has met the chain very often. The middle ring isn't in the best shape. I'd stay away. The crankset seems to be of the riveted type so you won't be able to replace just a single ring. Better shop for a new one. – Carel Aug 25 '18 at 18:01
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This is a common misconception. The shorter teeth are not chipped or broken off.

Modern chainrings and cassette sprockets have features to assist the derailleur with moving the chain. The shorter teeth allow the chain to more easily move off the chainring and onto an adjacent one.

Definitely fairly well worn. Personally I'd stay away from something this worn that does not have replaceable chainrings. Given it's possible to get new square taper cranksets for about $30 US, I'd look for something in better shape that will give you more service life.

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Those teeth aren’t broken; as you suspect they are thereto help the chain slip off and onto the little ring.

As for the spacing, it looks to me like 2 groupings roughly opposite each other at approx nine o’clock and three o’clock. Grouping is roughly 2 short, 1 tall, 2 short, giving five total. Therefore rough symmetry.

Same features on the outer ring, six or so shorter teeth in about the equivalent place. Not so pronounced though.

Notice also the ramps which are on the side of the ring, looking like deformed teeth. they help the chain up onto middle ring, two at the top and two at the bottom, five teeth apart in approx symmetry.

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