recumbent chain tubes

Hi

I am building a swb bent and the design i have uses plastic tubes to guard
the chain. I see that many use this idea, are they noisy. I assume the
chain must touch when changing gear due to the changes in the chain line, do
the mounts have a slide to allow the tube to move with the chain.

Any advice, comments on even better close up images of mounting arrangements
for these tubes appreciated.

Gary

"geepeetee" wrote in message
...
Hi

I am building a swb bent and the design i have uses plastic tubes to guard
the chain. I see that many use this idea, are they noisy. I assume the
chain must touch when changing gear due to the changes in the chain line,
do
the mounts have a slide to allow the tube to move with the chain.

I have no complaints about my chaintube other than I need to trim the end
since it's a little frayed from boing over the front chainring once

geepeetee wrote:
Hi

I am building a swb bent and the design i have uses plastic tubes to guard
the chain. I see that many use this idea, are they noisy. I assume the
chain must touch when changing gear due to the changes in the chain line, do
the mounts have a slide to allow the tube to move with the chain.

Any advice, comments on even better close up images of mounting arrangements
for these tubes appreciated.

Gary


Chain tubes have only two problems: they cause friction and they get
dirty, and are difficult to clean without breaking the chain.
I have a Sun SWB and put up a page showing what I did to it. The factory
tubes were long and the tube-brackets holding them were very stiff, and
the mount I made is free to le the tube move around to follow the
chainline.
This made a significant difference in drive friction on the bike.
http://www.norcom2000.com/users/dcim...ster_tube.html

.....
Ideally the boke should work with no tubes at all, but if that is not
possible then my suggestion is to use the absolute smallest length of
tubes you possibly can.

They are somewhat noisy. I have gotten used to mine but I am
considering modifying it to cut down on the noise and friction a bit. I
have a pic which shows the mounting hardware.

http://tinypic.com/6ojz8g.jpg

Basically, you can fashion something out of a wire hanger and some
clamps. I am sure you could come up with a different design that would
work as well. It does not have to be beefy to support the tube. My
tubes seem curved. I don't know if that's important though.

I use 1/2 " ID polypropylene tubing from the HW store. It can be
straightened by pushing onto a dowel rod, heating moderately in the kitchen
oven, and then quenching in cold water. The softer the tube material, the
less noise, so the polypropylene is perfect for a chain tube. I allow a
small amount of play with a couple of zip ties to allow the tube to follow
the chain line. I have both a swb and lwb Bentech and the chain lines are
both longer than on a conventional bike. Therefore, the chain angles are so
low that it just is not a problem in either case. Every year or two a zip
tie breaks and needs to be replaced.
"geepeetee" wrote in message
...
Hi

I am building a swb bent and the design i have uses plastic tubes to guard
the chain. I see that many use this idea, are they noisy. I assume the
chain must touch when changing gear due to the changes in the chain line,
do the mounts have a slide to allow the tube to move with the chain.

Any advice, comments on even better close up images of mounting
arrangements for these tubes appreciated.

Gary