Recumbent chain idler



W

Wally

Guest
I'm making a chain idler for my recumbent build. 3D CAD-piccy here...

http://www.melodolic.com/3D/Idler/Idler.htm

The metalwork is done, but I'm not sure about the pulley. The bearings it
fits onto are 22mm OD, and the overall diameter of the pulley is 35mm
(because that happens to be the size of nylon rod that I have lying around).
The thickness is 17mm and the chain runs in a groove 10mm wide by 4.5mm
deep.

Do folks reckon this shape would work okay, or might the chain have a
tendency to slip off? I've designed the spindle so that there is scope to
adjust the left/right position of the pulley to try and keep the chain path
central.


--
Wally
www.wally.myby.co.uk
http://iott.melodolic.com
 
M

Mike Causer

Guest
On Sat, 21 Jan 2006 21:18:51 +0000, Wally wrote:

> I'm making a chain idler for my recumbent build. 3D CAD-piccy here...
>
> http://www.melodolic.com/3D/Idler/Idler.htm


If you converted your pics to pdf, jpg, or something that more than just
the one proprietary program could read you might get a better response.


Mike
 
A

Alexander Rice

Guest
Mike Causer wrote:
> On Sat, 21 Jan 2006 21:33:34 +0000, Wally wrote:
>
>
>>http://www.melodolic.com/3D/Idler/Idler.jpg

>
>
> On the idle side - maybe, on the load side - no.
>
>
>
> Mike


I'm not sure it'll work on either side, I rekon the groove is just too
shallow, for reference the drive side idler on the catrike is 65mm dia
with a groove that's 12mm deep and tapers from 10mm to 8mm wide. I think
it's got an O-ring at the bottom as well to keep it lovely and quiet.

Alex
 
M

Mike Causer

Guest
On Sat, 21 Jan 2006 23:25:34 +0000, Alexander Rice wrote:

> I think it's got an O-ring at the bottom as well to keep it lovely and quiet.


On the Speed Ross, with idler from who knows where, I find a piece of old
inner tube cut to the inner width of the pulley, and replaced about every
3 months when the oil on the chain rots through it, works.


Mike
 
N

Nigel Cliffe

Guest
Wally wrote:
> Mike Causer wrote:
>
>> If you converted your pics to pdf, jpg, or something that more than
>> just the one proprietary program could read you might get a better
>> response.

>
> It's a 3D CAD file which can be rotated and zoomed, and parts can be
> hidden or made trasparent. Here's a screen grab...
>
> http://www.melodolic.com/3D/Idler/Idler.jpg



Don't think the loads will work, but depends on the material sections.

I've seen successful idlers on recumbents by using the wheel with bearings
from a skateboard. Turn a grove into the wheel to carry the chain.



- Nigel



--
Nigel Cliffe,
Webmaster at http://www.2mm.org.uk/
 
R

Rod King

Guest
Wally

Iv'e a similar arrangement on my Windcheetah. Works well, except the chain
can jump off on fast rough roads. The answer is a bolt going through the
brackets and across the outside of the chain. Of course it normally takes no
load at all.

If you are looking at the idling side then the Windcheetah gets by with just
a nylon block with a hole machined in it for the chain to slide through.

Regards


Rod

"Wally" <[email protected]> wrote in message
news:%[email protected]
> I'm making a chain idler for my recumbent build. 3D CAD-piccy here...
>
> http://www.melodolic.com/3D/Idler/Idler.htm
>
> The metalwork is done, but I'm not sure about the pulley. The bearings it
> fits onto are 22mm OD, and the overall diameter of the pulley is 35mm
> (because that happens to be the size of nylon rod that I have lying

around).
> The thickness is 17mm and the chain runs in a groove 10mm wide by 4.5mm
> deep.
>
> Do folks reckon this shape would work okay, or might the chain have a
> tendency to slip off? I've designed the spindle so that there is scope to
> adjust the left/right position of the pulley to try and keep the chain

path
> central.
>
>
> --
> Wally
> www.wally.myby.co.uk
> http://iott.melodolic.com
>
>
 
A

Alexander Rice

Guest
Rod King wrote:
> Wally
>
> Iv'e a similar arrangement on my Windcheetah. Works well, except the chain
> can jump off on fast rough roads. The answer is a bolt going through the
> brackets and across the outside of the chain. Of course it normally takes no
> load at all.
>
> If you are looking at the idling side then the Windcheetah gets by with just
> a nylon block with a hole machined in it for the chain to slide through.
>
> Regards
>
>
> Rod


I wouldn't model you chain mangement on the Windcheetah, not the return
side at least beacuse it's rubbish (sorry, I've got one too!). A return
chain tube would have been much better and would have stopped the chain
swinging about, slapping into the main tube, been a lot quieter, not get
jammed over bumps and not sometimes de-rail at the front if you go over
a bump and aren't pedalling.

Alex
 
W

Wally

Guest
Alexander Rice wrote:
> Mike Causer wrote:
>> On the idle side - maybe, on the load side - no.


> I'm not sure it'll work on either side, I rekon the groove is just too
> shallow, for reference the drive side idler on the catrike is 65mm dia
> with a groove that's 12mm deep and tapers from 10mm to 8mm wide. I
> think it's got an O-ring at the bottom as well to keep it lovely and
> quiet.


The bracket I have will take 60mm, so I think I'll track down some bigger
pulley material.


--
Wally
www.wally.myby.co.uk
http://iott.melodolic.com
 
R

Rod King

Guest
"Alexander Rice" <[email protected]> wrote in message
news:[email protected]
>
> I wouldn't model you chain mangement on the Windcheetah, not the return
> side at least beacuse it's rubbish (sorry, I've got one too!). A return
> chain tube would have been much better and would have stopped the chain
> swinging about, slapping into the main tube, been a lot quieter, not get
> jammed over bumps and not sometimes de-rail at the front if you go over
> a bump and aren't pedalling.
>
> Alex


I am not sure how a return chain tube would be much better as it would still
need to take in the angles. Presumably it would have to be fixed near the
front idler wheel. I have never had the chain jam over bumps and the
occassional de-rail is when going downhill is over bumps when the simple
solution is just to change gear back onto the front chainwheel.

However, I have no experience of chain tubes. If you do fit one please let
me know how you get on with it.

Regards

Rod King
Windcheetah #456
 
W

Wally

Guest
Mike Causer wrote:

> On the Speed Ross, with idler from who knows where, I find a piece of
> old inner tube cut to the inner width of the pulley, and replaced
> about every 3 months when the oil on the chain rots through it, works.


Thassa good idea - I'll keep that in mind.


--
Wally
www.wally.myby.co.uk
http://iott.melodolic.com
 
W

Wally

Guest
Nigel Cliffe wrote:

> Don't think the loads will work, but depends on the material sections.


Do you mean the chain tension won't be enough to keep it engaged with the
pulley?


> I've seen successful idlers on recumbents by using the wheel with
> bearings from a skateboard. Turn a grove into the wheel to carry the
> chain.


The bearings are reputed to be for skateboards and roller blades - 20mm OD,
8mm ID, 7mm thick.


--
Wally
www.wally.myby.co.uk
http://iott.melodolic.com
 
N

Nigel Cliffe

Guest
Wally wrote:
> Wally wrote:
>
>> The bearings are reputed to be for skateboards and roller blades -
>> 20mm OD,

>
> Typo: 22mm OD.


The other trick I've seen employed with the skateboard wheel is to turn two
groves in the wheel, one for the power route of the chain (nearer the
frame), and one for the return path. The wheel has to be rotated by the
power path, so might as well go round and help the return path along its
way.



- Nigel



--
Nigel Cliffe,
Webmaster at http://www.2mm.org.uk/
 
If you are going to try the skateboard wheel route, make sure that you
get the ones that are the same material all the way through - some have
a 4-5mm coating which you cut through when turning the groove rendering
them pretty useless.
 
A

Adrian Godwin

Guest
Wally <[email protected]> wrote:
>
> The bracket I have will take 60mm, so I think I'll track down some bigger
> pulley material.
>


I've got some 50mm nylatron (molybnedum disulphide-loaded nylon) that might
work well. Also some 50mm black nylon.

-adrian