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Old 09-19-12, 02:58 PM   #1
ronfinch
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Hopefully simple chainring question

Hi all,

My current chainset consists of a 30, 39, and 52 teeth chainring. I am considering installing an internally geared hub, and have been looking at ratios between chainring and rear cog.

I am also planning on buying a 9 speed cassette and trying a single chainring up front in the meantime.

My question is, as far as I can see, if I want a chainring 39 teeth or smaller, I have to install it to the inside of the spider. It doesn't look particularly neat, which isn't really a problem, but will it be secure mechanically? Do the three chainrings need to be bolted together to be secure?

Also, I don't think I could go much lower than 39 teeth in the current middle ring position. Can I use the bottom ring position? Will I encounter chainline issues in either the IGH or rear cassette single chainring scenario? What do people normally do in this circumstance?


Thanks in advance!

Ron
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Old 09-19-12, 03:55 PM   #2
HillRider 
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Assuming you have a common 130/74 mm bcd road crank, 38T is the smallest you can use on the outer bolt circle so the 39T is not worth changing. You could install the 39T ring on the outside of the spider if you wish. In any event, a single chainring will require a set of shorter chainring bolts and these are available.

Using the inner (granny ring) position only will indeed give chainline problems.
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Old 09-19-12, 05:03 PM   #3
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Hi,
Thanks very much for the reply. Checked and yes they are 130/74mm bcd.

I guess that if I decided to install the 39 tooth ring (or (at some point in the future) a 38t single speed chainring) in the outer position I would be able to align the rear sprocket on an igh with a spacer in the back?

I also guess that putting the chainring in the outer position, with a cassette installed, probably wouldn't make a huge amount of difference in terms of diminished performance, as I would have a chainguide on the front anyway, but it wouldn't add anything either....

Thanks again.
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