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 Post subject: Gear Ratio's
PostPosted: Fri Oct 16, 2009 12:57 am 
Retro Guru

Joined: Thu Sep 17, 2009 11:41 pm
Posts: 830
Location: Ramsgate, Kent, UK
Hi all,

Hope you can help with a query I have with regards to gear ratio's.

I know that when calculating your gear ratio you divide that front ring number of teeth by the rear sprocket number of teeth and multiply by the rear wheel size.

So lets say I have 48/12*26 this gives me a 104 inch top gear, however, I'd get the same if it were 44/11*26.

So the question is, is one of the 2 options better than the other or doesn't it matter?

Thanks

Jules


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 Post subject:
PostPosted: Fri Oct 16, 2009 8:03 am 
Old School Grand Master

Joined: Tue Oct 09, 2007 1:55 pm
Posts: 8222
Location: New Forest, UK
In terms of the effect at the wheels then you are right - it's the same.
44/11, 48/12, 52/13 are all the same.

However, running larger chainrings has some advantages: the pedalling loads are spread over more teeth and the chain runs at lower tension. Both of these mean lower wear across the whole drivetrain.

However, running smaller chainrings allows a wider gear range with the same rear mech (less chain slack to wrap between gears) and is a little lighter.

Generally with road kit you start to run into problems if you go below 46T on the outer.


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 Post subject:
PostPosted: Fri Oct 16, 2009 9:48 am 
Retro Guru

Joined: Thu Sep 17, 2009 11:41 pm
Posts: 830
Location: Ramsgate, Kent, UK
Hi Hamster,

Thanks for the information.

I thought there would be a difference, it is nice to now know what it is.

I must say though, I have been running a 44/11 set up and didn't have any issues but was thinking of changing this as I am currently rebuilding.

Now time to get my thinking cap on and decide what route to go.

Regards

Jules


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