Derailluer lengths??

[sommerfliesby]

Been riding a ss the past couple years, but trying to get the geared bike going again. I went to replace my SRAM 9.0SL rear and I find I now have a choice of lengths...anybody know why and what diff it makes?

[rockyrider]

gear range... if you're doing a triple up front and 11-30 or more at the rear you should think of a long cage. Only consider a short cage if you are very rigorous about keeping the rear cogs to a minimum for any front ring. (eg. 44 to highest 3-4 cogs, 32 to middle 3-4 cos, 22 to largest 3 cogs). More detailed math here (http://bluecollarmtb.com/2007/06/19/rear-derailleur-capacity-explained/).

[sommerfliesby]

Thanks RR...I'll get it on order today.