DETERMINING PROPER CHAIN LENGTH
The chain of a bicycle or tricycle is something which is sometimes ignored and taken for granted. Yet it is so very important. You can have the very best bike or trike and components money can buy and keep it all in tip top shape, but if you ignore the chain to where it fails or it just breaks you can’t and won’t go anywhere. Some other parts on a cycle could fail, even fall off, and you would still be able to ride it, but if the chain fails you are “dead in the water”. You will just sit there and “spin” all day.
I have previously written about chains mainly covering care, maintenance and wear. HERE is a link to that article. And HERE is another article on this subject where I shared a video produced by ICE trikes.
When it comes time to replace the chain or if the boom is being repositioned more than a short distance it is imperative that the chain be the correct length for everything to work correctly and without causing any damage to the rear derailleur (if you have such an animal on your trike).
Below is a very short video covering how to determine the correct chain length. In the video the rear derailleur “cage” is referred to. The cage is that portion of the derailleur that has the two small idler pulleys the chain runs thru. Here is a picture with the cage outlined in red. Please be aware that in this picture the chain is not positioned on a “center” cog as is necessary in determining the proper chain length. The picture does, however, show the cage in the approximate 6 o’clock position.
Near the end she said the rear derailleur should be in the six o’clock position in relation to the rear derailleur. Although you hopefully understood this I want to clarify it. The cage with the two idler pulleys should be in the 6 o’clock position. In other words the two idler pulleys should be in line with each other vertically (perpendicular off of the ground/floor) one above the other … like the picture above shows.
I caution you when replacing a worn chain … do not put a new chain alongside of a old worn chain to match it’s length as a worn chain will be longer than a new chain so this method is flawed. If your old chain was the correct length you can safely count the links and match them on the new chain. Or you can use this method shown in the video to determine the proper length. Keep in mind however, that this method using the position of the cage in the 6 o’clock position may be slightly off depending upon your particular application. Be sure to check it carefully according to the instructions in the next paragraph.
The thing you need to be sure of is that when the gear selection is largest chain ring (sprocket) on the front to the largest cog (sprocket) on the rear your derailleur will handle it and that the cage not come too far forward horizontally and run out of “effect” to where the chain tightens up. If this happens the chain can damage the derailleur. In the opposite gear selection … smallest sprocket on the front to the smallest on the back the rear derailleur cage should handle the chain without the chain coming back onto itself and rubbing as the pedals are turned.
One way to determine proper chain length is forget about running the chain thru the rear derailleur and just place the chain over the largest front chainring (sprocket) and on the largest rear sprocket and add 2 links or 1 link + Power Link (missing link). After you make the chain this length then go ahead and route it thru the rear derailleur before assembly. Be sure not to have a twist in the chain when you go to connect the two ends together.
Too short of a chain is more of a concern than too long. Too long will just result in the chain drooping and possibly the derailleur not being able to handle all the extra chain resulting in not being able to go into all the gears. And as I said, too short of a chain can result in damaging the derailleur … turning it into a pretzel. And rear derailleurs are just too expensive to go around making them into pretzels.
Ensuring that the chain is the correct length and keeping it in good shape we enable you to …
KEEP ON TRIKIN’
Posted on March 11, 2015, in components, maintenance/repair, tadpole trikes, videos and tagged damaging rear derailleur by too short of chain, determining proper chain length, tadpole trike chain length. Bookmark the permalink. 3 Comments.