Originally Posted by
makosz81
I have a 2011 felt Boughmann I think gear ratio of 2.75( 17 teeth in back and 47 in front that I counted) Sometimes it is too small and want more. Is it possible to change the one side of rear tire to have a fixed gear with 12 teeth instead of the current ss and the other side still with the 17 teeth? How much would that make me faster? Also would it just be better to change my front gear to 52?
If it is what would be the cost to have that changed?
Gear inches is a more common way to express gearing around here. There's a great calcuator at this site:
http://www.sheldonbrown.com/gears/
Calculating for yours assuming you've got 700c wheels and 25c tires (pretty normal) you're currently at 72.9 gear inches (gi). Most people find that somewhere between 73-75 gear inches is the most practical single combo but this of course depends on how hilly your riding gets. If you live somewhere really flat you could of course push it higher. Using a 12t cog (which is REALLY tiny) you would be at 103.3 gi. Pretty much nobody rides a fixed gear with that high of gi on the street and it's especially dangerous brakeless. My recommendation would be to try maybe a 15 tooth cog if you really feel like you're spinning too fast with your 17. Another alternative is to get really good at spinning at a high cadence. If you haven't been riding fixed for long, you may just not be used to how fast you'll have to pedal some times.
Oh and I totally forgot to address your main concern. You can only safely run two fixed cogs of you have a Fixed/Fixed hub which isn't super common. Look to see if the extra side has two sets of threads (one bigger and right hand thread, and the outer smaller and left hand). If I'm spoonfeeding this it's only because you're new and I don't know how much background you have with sw8 fixays.