Singlespeed & Fixed Gear - anyone ever built a chain tensioner?
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I picked up a trek 1400 frame the other day on the cheap. Anyway it has vertical dropouts, so I would need a chain tensioner.
Has anyone ever made one? I figured I a busted RD and some creative welding or something might get the job done.
I know they are like 20$ for a cheap one, but what the hell might as well give it a shot.
probably just the derailleur and liberal use of the limit screws will do ya'.
04-22-11, 01:49 PM
I "made" one out of an old rear derailer once. It was terribly ugly, but it did work fairly well. I removed the lower pulley and just ran the chain around the upper pulley. I must note that I did have some problems with chain wrap, where the chain would skip under load. I decided to stop messing with it and found the magic ratio instead. Much cleaner, much smoother, but it made gearing changes virtually impossible.
I've seen someone make one out of a V brake arm once. It was pretty cool. I think it's best if you can have something which locks into place, preferably in "push-up" mode. Then you don't have the chain bouncing around. I'm thinking about making one this weekend so I will update if I can get something to work well.
04-22-11, 03:09 PM
I made one with the side of a rear derailer arm once. Very simple, just the pulley and the half arm, IIRC(was years ago). Bolted the top of the arm to the hanger, with a spacer to keep it loose enough to pivot. Bent the arm in two places for the correct chainline spacing. Used a wide innertube rubber band for the spring. Actually worked quite well.
04-23-11, 01:38 PM
Using a rear derailer as a chain tensioner is only ugly if you start with an ugly derailer. I used an old Campy NR rear derailer as a chain tensioner and it was gorgeous.
04-23-11, 02:25 PM
Well if you access to the machine tools and an old rear derailleur, you can salvage the pulley wheels and whip up something much compact and simplified for a cleaner look.
04-23-11, 03:04 PM
One of these (Huret Svelto) ought to work pretty well as a tensioner:
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