9 speed and 10 speed crank difference

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2008-12-16 2:04 PM


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Subject: 9 speed and 10 speed crank difference

I have been buying parts to build 2 bikes from craigslist and ebay and should have done my homework first.  I have most of the parts to make 1 nice bike (a ten speed) that needs a crank and bottom bracket.  I ended up buying a 105 crank for it that is older and maybe not compatable with 10 speeds.  On the other bike ( a beater) it has a bottom bracket so I need a crank for it but the bottom bracket is square taper and the 105 crank is octalink!  

Before I buy more parts that might not work, does it make a difference if the crank is 9 or 10 speed specific?  I think that the bottom bracket length is specific to a double or triple crank. So I wonder if the difference is just in the bottom bracket length?  I think I may need to buy both a bottom bracket and crank for the 10 speed.

also, any advice on a crank to fit my square taper bottom bracket for my beater? 



2008-12-16 3:13 PM
in reply to: #1857013

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Subject: RE: 9 speed and 10 speed crank difference

The bb size is determined by the crank and the frame.  If you have a traditional square taper BB, then you need to find the spacing of it (length in mm).  From there you would just need to find a properly splined cran that will work with the bb spacing.  Otherwise you run the risk of having the arms or rings hitting the frame.

You can run a 9 speed crank with 10 speed.  The crank itself is not the issue, it is the chainrings but in most instances you can run either a 9/10 on them.  A 10-speed chain is just slightly narrower.

2008-12-16 4:54 PM
in reply to: #1857013


22

Subject: RE: 9 speed and 10 speed crank difference

Ok.

i assume from your post I can use my 9 speed crank shimano 105 53/39 with my new 10 speed shifters.  can I go backwards and get a bb to match the 105 crank 53/39 I bought?

2008-12-17 11:20 AM
in reply to: #1857375

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Subject: RE: 9 speed and 10 speed crank difference

Of course.

A Simano octalink BB will only run you about $25 or so for a 105 model.

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