chain tube brackets - advice wanted

Hi

I'm just at the later stages of building a swb recumbent and need to devise
some brackets for the chain tubes, obviously they have to move sideways and
up and down to accommodate gear changing.

Any advice (or images) appreciated

thanks

Gary

I would say try living without tubes if you can. They are noisy and
add drag. Since they don't have a lot of force applied to them, they
can be added after-the-fact if you decide you can't live without them.

I either tuck my pant leg into my sock (very unfashionable) or use a
velcro strap to hold my pant leg away from the chain (almost
unfashionable). I've ridden my homebuilt SWB for about 600 miles now
and haven't had any chain-rash on my pants yet.

666.net wrote:
I would say try living without tubes if you can. They are noisy and
add drag.

They /must/ add some drag, but IME not a huge amount. IME they're not
really noisy either.

Since they don't have a lot of force applied to them, they
can be added after-the-fact if you decide you can't live without them.

This is very true...

I either tuck my pant leg into my sock (very unfashionable) or use a
velcro strap to hold my pant leg away from the chain (almost
unfashionable).

You can get wee snap around reflective bands very cheaply now, which
seem to be quite popular and they even do the job!

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net http://www.dundee.ac.uk/~pjclinch/

geepeetee wrote:
Hi

I'm just at the later stages of building a swb recumbent and need to devise
some brackets for the chain tubes, obviously they have to move sideways and
up and down to accommodate gear changing.

Any advice (or images) appreciated


None of what I am about to say mentions helmets (oh, damn).

If you have to use chain tubes you will want to either fix them to the
frame or fix them in relation to each other, as in I assume that you
will be using a drive and return chain tube. The simplest method is
strip of metal with holes drilled at each end and P-clamps for the tubes
bolted to these, then use cable ties to anchor this metal strap in orbit
from the frame. As the chain line is generally going to bring the chain
tubes near but not touching the frame then a cable tie loop from this
strap to another cable tie that tightly holds one end of the loop to the
frame is sufficient. You can get the P-clamps from your LBS, they are
commonly used for mudguard and rack mounts.
If however you are trying to sort out chain tubes to sit either side of
a middle-drive or chain pulley then you are probably looking at actually
bolting this metal strap between said device and the frame.
For anything more complicated you will need to give further details of
your SWB design for us to prod at and argue over.

Just use "zip ties" or "cable ties". One wrapped around the tube and
one secured by and beneath the first and at right angles to the first
and attached to the immovable portions of the frame. Cheap, light,
flexible, quiet, need I go on? I've used these for thousands of miles
with no adverse affects and only one zip tie broke. I discovered it in
my bike check before a ride and replaced it at home...to guarantee that
I never have another broken one; I carry spares.

dj.

On Sun, 6 Nov 2005 19:51:25 -0000, "geepeetee"
said in :

I'm just at the later stages of building a swb recumbent and need to devise
some brackets for the chain tubes, obviously they have to move sideways and
up and down to accommodate gear changing.

My bike has PTFE chain tubes which are quite flexible. A rigid
bracket at one end allows for enough movement not to be a problem at
the other.

(rummages around for a picture)

http://www.chapmancentral.co.uk/web/...optima_stinger

The upper tube is secured by a rigid (folded steel) bracket which runs
along its length for about 4" at the main idler.

The lower one is secured by a P clip where it crosses the frame.

That's all the support they get.

Guy
--
http://www.chapmancentral.co.uk

"To every complex problem there is a solution which is
simple, neat and wrong" - HL Mencken

wrote:
Just use "zip ties" or "cable ties". One wrapped around the tube and
one secured by and beneath the first and at right angles to the first
and attached to the immovable portions of the frame. Cheap, light,
flexible, quiet, need I go on? I've used these for thousands of miles
with no adverse affects and only one zip tie broke. I discovered it in
my bike check before a ride and replaced it at home...to guarantee that
I never have another broken one; I carry spares.

Duct tape can work to secure a chain tube in a temporary repair
situation.

I have no experience using cable ties for chain tube retention, but a
long time (relatively speaking) recumbent dealer suggests that they do
fatigue fairly rapidly. [1] However, spare cable ties are of course,
inexpensive, compact and lightweight.

Black cable ties are preferable for recumbent bicycle use, since they
are more UV resistant than the translucent versions.

[1] Fatigue life will depend on how much strain the cable tie is
subjected to each cycles.

--
Tom Sherman - Fox River Valley
"Twisting may help if yawl can chew gum and walk." - G. Daniels