umm, yeah. what else is in the bottom end? Yeah, replace or reinforce it <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/wink.gif" border="0" valign="absmiddle" alt='
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Pretty broad question though. Building the SR for what exactly? You can always ballance the crank. I know there's treatments and stuff for it, but I dono what. Bearings and stuff too.