Tension Roller Tweaks

happycheapskate

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Joined
Nov 5, 2009
Messages
1,392
Re: converting 10speed/mountain bike der. to tensioner, easy solutions

I was into the single speed craze in my early 20's and came up with 2 good ways to convert old rear derailleurs into tensioners.

1. Find a thick spoke or piece of coat hanger.
Bend a tight hook onto one end. Insert the straight end, in place of a cable, into the barrel adjuster, and into the cable groove/tightening nut. Adjust the derailleur for alignment, and cinch down hard on the wire. Trim with tin snips, plier/dykes, or a good cable cutter. Now you can adjust the alignment with your fingers, slightly, or make major adjustments just like a cable. This works great. You can also add a longer screw to the "Hi" limiter to back up the wire.

2
If you want it to be smaller, or only use one pulley, you can cut down the right side of the cage, and replace the screw with a machine screw, small washers for spacing (wide chains) nylock nut, and large washer. Preferably a big silver dollar sized washer made from a lid of a tin can and ground dull.
This large washer replaces the left side of the cage and prevents the chain from ever possibly falling off the pulley.

This worked great for months on a mountain bike single speed.



I have been thinking of welding a der. hanger somewhere to use an old derailleur in this manner on the motor side, but thought better of it. Those pulleys aren't trustworthy enough.

I want the auto spring tensioner that mounts on the seat tube. Where to buy?

Unfortunately, most derailleurs you find are multi-speed, so they will be spring-loaded and cable-operated. What you need for this application is a single-speed derailleur, which are pretty rare. I couldn't find one at any local bike shops, so I had to order it online.
 
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happycheapskate

Active Member
Joined
Nov 5, 2009
Messages
1,392
I ran this bike with no tensioners on either side, for 300 miles, but the grubee chain stretched and started jumping, and I've had some instances of the axle being pulled a little by the motor, loosening the chain. I'm getting/making an axle puller for that issue.


Now am using the tensioner on the pedal side, works great for that, and feels safe.



Thread about 410 vs 415 chains and Tractor Supply 41 chains etc.
http://motoredbikes.com/showthread.php?t=25912j

Thread about idler pulley related accidents
http://motoredbikes.com/showthread.php?t=26374
 
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