"Cheaper" option for the 50.4 cranks. I picked up a set on sale for $75. The arms use a normal puller and come w/ self-extracting bolts. I put a VO outer chainring on (running 10 speed chain) and the arms are bowed a bit so there are no issues clearing any kind front derailleur. Nice adapter!
http://store.electrabike.com/eSource..._/_750027.aspx
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