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Old 03-21-05, 11:11 PM   #1
MicahWedemeyer
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Problems installing new chainrings

Hi,

I'm trying to install a new set of chainrings on my Schwinn Homegrown. It has a triple set of 58/94 BCD size, as best I can tell.

Using the crank puller, I was able to get the crank off and pull off the old chainrings. However, I am running into a problem. The old inner chainring (granny?) bolted into the middle chainring. The new middle chainring has no inner bolt circle. Therefore, there is no place to attach the inner chainring.

A book I have mentions that the granny ring should bolt directly into the crank arm (spider?) Does this mean that I have to buy a new crank arm?

So basically, I need some basic info on cranks/chainrings. Here are the questions I need answered:

1) Do crank arms come with and without an inner set of bolt holes?

2) How much do crank arms cost?

3) Am I missing something? Is there another way to attach the granny ring even though neither the middle chainring nor the spider has an inner bolt circle?

4) What should I do????


Thanks for all the help!
Micah
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Old 03-22-05, 07:51 AM   #2
sydney
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Quote:
Originally Posted by MicahWedemeyer
Hi,

I'm trying to install a new set of chainrings on my Schwinn Homegrown. It has a triple set of 58/94 BCD size, as best I can tell.

Using the crank puller, I was able to get the crank off and pull off the old chainrings. However, I am running into a problem. The old inner chainring (granny?) bolted into the middle chainring. The new middle chainring has no inner bolt circle. Therefore, there is no place to attach the inner chainring.

A book I have mentions that the granny ring should bolt directly into the crank arm (spider?) Does this mean that I have to buy a new crank arm?

So basically, I need some basic info on cranks/chainrings. Here are the questions I need answered:

1) Do crank arms come with and without an inner set of bolt holes?

2) How much do crank arms cost?

3) Am I missing something? Is there another way to attach the granny ring even though neither the middle chainring nor the spider has an inner bolt circle?

4) What should I do????


Thanks for all the help!
Micah
Some grannys bolt to the middle ring. Simple enough.
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Old 03-22-05, 09:53 PM   #3
John E
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There are at least three ways to assemble a triple:
1) (most common): the two outer rings bolt to the spider and the inner bolts to a smaller BCD set of holes on the inside of the spider. This is the system for which your new chainrings are designed.
2) (triplizer; your old setup): the two outer rings bolt to the spider and the inner bolts to a second row of holes in the middle ring. If you want to retain this system, you will need a new middle ring which has the second set of holes, as your old one did. Harris Cyclery or LooseScrews may have what you need.
3) (least common, smallest range): all three rings bolt onto a single set of holes in the spider, using long stack bolts and spacers.

If you want to go with the first option, you will need a new right crank. The second option will require you to exchange that new middle ring for a triplizer ring. The third option will require you to accept a larger grannie and buy a set of long stack bolts, assuming you can find them. They are pretty rare.
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Old 03-23-05, 09:22 AM   #4
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Thanks John, that's exactly the kind of answer I needed!
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Old 03-24-05, 09:00 AM   #5
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I found the following right crank at LooseScrews:
http://www.loosescrews.com/index.cgi...id=43953369607

My only question about it is this: The crank is listed as a 95/58 BCD. Can this be correct? I thought that the standard compact crank BCD is 94/58.
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