Originally Posted by ricardo kuhn
[...]similar concept so the frame does not need to be modified diminishing the amount of comitment like if you need to weld part to the frame and then somehow don't don't like the results to much, plus simplified the adaptavility to diferent type of bikes and frame configurations
Ricardo,
Actually it's a lot cheaper and simpler than you think: the extension you see at the bottom of the bike isn't welded at all, it's bolted onto the bike: vertically it's held exactly like a kickstand, with a plate to press against the stays from the topside (in fact, it is from a hacked kickstand), and it's guided sideways with a bolt that goes through the mudgard hole in the small crossmember between the two stays. I could install this boom on virtually any bike.
The boom is an old table leg, so it's definitely cheaper than a chain guide. Besides, the guide wouldn't work because the idlers need to be quite far apart to make the chain describe a large enough "V" to go around the granny ring. Also, the top idler (the one attached to the seat tube) is used to tension the chain by sliding it up and down the tube. Not sure I'm very clear here, but believe me, a guide wouldn't work
