^^^ WimVDD , I would def. try "crossing the streams" with that rear brake cable straddle. Among my GTs, the ones with the guide have them croseed, and the ones without the guide go direct.

Also, did you notice how heavy-duty that straddle cable is? Looks like something used on the Mackinac Bridge. My Schwinn Impact Pro came stock with that gauge for all the brake cables. Probably overkill, but impressive looking.

I once had a guy tell me that the groove tube design made the top tube weak. He had nothing to back up his claim, however, and he's one of those guys who are prone to bold claims.