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Old 09-27-11, 03:09 PM   #1
hairyman
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chainring replacement question

Hey everyone, I'm in the middle of a major overhaul of my primary bike and I'm stuck trying to figure out what replacement chainring to order. I'm hoping someone with more mechanical knowledge can help me out.

The bike dates from the late 90's and has JIS square-taper cranks and 22-32-42 rings. The middle ring is badly worn and I need to replace it.

The outer ring is attached with four bolts through the spider to threaded holes in the middle ring. The inner rings are both inboard of the spider and are attached to each other with four bolts that accept a hex key but won't begin to budge.

This photo shows the crank, the outer ring (with bash guard) and the two inner rings:


Here is the inner side of the two small rings:


I measured the BCD of the big ring at 104 mm so I ordered a new 32T ring in that size. Once I took the crank and chainrings off, though, I realized that the new ring won't fit in the middle position where I need it. The only place it will fit is in the outer position.

Does anyone know if I can get a 32T ring that will replace the middle ring? Or is my only option to completely replace the cranks and rings?
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Old 09-27-11, 03:46 PM   #2
fietsbob 
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Have you checked with any local bike shops , might be a bin
with stuff that is in better shape, that customers broke something else.

the cheaper stuff uses steel for the smaller cogs, so wear longer
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Old 09-27-11, 04:08 PM   #3
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From your pictures it appears the middle and granny ring are riveted together and cannot be separated for replacement. This is a relatively low line inexpensive crank and you would do better to replace the entire thing.
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Old 09-27-11, 05:05 PM   #4
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Replacing all the chainrings on a low end crankset is a losing proposition. Replacing one or two might be OK, but if you shop around you can often find complete cranksets for very close to the price of the three chainrings.

I've even seen the crankset for less than the price of the 3 rings. It's as if they're charging you for taking it apart to sell the rings. In your case you should be able to get an upgrade over what you have without spending much more dough.
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