The dispised chain idler

tdh10

New Member
Oct 3, 2018
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I assume most of you with China Girl tiddlers despise that infamous idler as much as I do. Here is my solution before I clean it up with rounded corners etc. so it is easier to understand. I started with sections of bed frame because it is thin and strong. I replaced the roller bolt with a 5/16" carriage bolt and milled half through one of the ells to share the square neck with the bracket and the slot the roller bolt runs in. The bolt head was reduced to 5/8" as that is what the diameter of my center-cutting end mill was. This will allow tightening the damned bolt from the backside only. The adjusting bolt is a 2-1/2" X 5/16" total threaded one. It is anchored with a nut and the adjustment is done with the 2 nuts on the anchor ell. I shortened one leg on one leg to make adjusting range and used a square file to make room for the bolt square.
 

crassius

Well-Known Member
Sep 30, 2012
4,032
155
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USA
the tensioners are never a problem when done right - during use, there should never be any strain on a properly adjusted tensioner

any problem mean that tensioner is either not in line with chain, or was adjusted so that chain still has a tight spot that forces roller downward
 

Venice Motor Bikes

Custom Builder / Dealer/Los Angeles
Mar 20, 2008
6,611
419
83
Los Angeles, CA.
Whenever I absolutely have to use a tensioner, I cut off the lower half & weld it to the chainstay of the frame.

I can set it in the perfect position, it's much stronger & (I think) it looks better. ;)
 

crassius

Well-Known Member
Sep 30, 2012
4,032
155
63
USA
seen those

usually they get put on before chain has done its initial 1/2 inch stretch so that within a couple months the chain is too long to be adjusted further, new chain then needs to be put on even tho old one would work fine for a long time yet

1/2 links for 415 are often a bit off in size so that with a 415H they need some grinding to fit - labor to grind it is close to price of new chain

I prefer being able to move tensioner back an inch or so.