2012 Trek Mamba going 1x9...help?- Mtbr.com
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  1. #1
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    2012 Trek Mamba going 1x9...help?

    Well I finally bit the bullet and bought a mamba yesterday. I purchased a 34T race face bash guard planning of going 2x9....after some thought I think I might go 1x9. Currently the front crank rings are 22/32/42. My question(s) is this...

    How many teeth up front convert to number of teeth on the cassett? Is it like 1 tooth up front = 3 teeth in the back or something like that?

    If I changed to a 1x9 can I buy a 26T and the 34T race face bash be ok to use?

    Will these work?

    Race Face Race Rings 4 Bolt at JensonUSA.com

    Do I really need a chain guide?

    Any help would be greatly appreciated. Thanks!
    Cycle tracks will abound in Utopia. ~H.G. Wells

  2. #2
    nocturnal oblivion
    Reputation: stumblemumble's Avatar
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    1) If you go 1x9 you will need an upper guide, in 2x9 or 3x9 the derailleur acts as a guide, simplest 1x9 guide is an inner bash/guide plate creating a bash sandwich. Check out BBG for these.

    2) Lower guide is not nearly as necessary for keeping the chain on. Mainly a lower roller keeps things quiet with the added benefit of never dropping a chain again. Check out the Blackspire Stinger for this.

    3) The equivalence of the front to rear gears is just the ratio (Divide chainring teeth number by the cog teeth number). Get out your calculator! For example 22 up front and 22 in the rear is a ratio of 1, same as 26 tooth front and rear. These two setups will be identical. If you want to go nuts or don't have a calculator, look here: Sheldon Brown's Bicycle Gear Calculator

    4) Those rings will probably work, 64/104 is fairly standard for mountain inner ring/outer ring. But you need to check and be sure. Look here for how to measure your cranks bcd (bolt circle diameter): http://www.blackspire.com/site_asset...CD%20Guide.pdf
    "...like sex with the trail." - Boe

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