Long Chain Idler Issue



B

Blackburn Pete

Guest
I am riding an Evox LE (Semi-Recumbent) in Ottawa, Ontario, Canada and I
am hearing a lot of noise from the single chain idler on the return
portion of the chain. The idler is riding on a post that is mounted on a
hanger from the frame. There is no bearing there, only a bushing and I
would like to find a suitable replacement that has sealed bearings. The
current idler has about an inch (2.5 cm) of shaft to accomodated the
side to side chain movement on the 8-speed cassette. Has anyone got some
advice concerning the following questions?

Is it necessary to allow that much play for the idler to travel side to
side?

Should I use a modified roller-blade/skateboard wheel with a groove cut
out for the chain?

Should I get a sealed bearing derailleur idler with teeth and use that?

Is there a company that could supply an idler with sealed bearings?

The same bike is also branded as a Mikado Quetzal LE. Here is a link to
the specs.

http://www.mikadobicycles.com/en/popup_specs.asp?id=5

I am refering to the idler near the back wheel rim.

Thanks for your help.
 
M

Mike

Guest

> Is it necessary to allow that much play for the idler to travel side to
> side?


too little side-side play will result in high angles at the
chain/derailleur/chainring/cluster. Wedgies do ok with high angles, but not
the extreme inner-outer or outer-inner.

> Should I use a modified roller-blade/skateboard wheel with a groove cut
> out for the chain?


That's a fair approximation of what other idler wheels look like. And
probably how they start their life. There are not enough bents to warrant a
special production run just for us (sadly).

> Should I get a sealed bearing derailleur idler with teeth and use that?


They are a smaller diameter than the idler wheels, and without enough tension
on the chain it may hop off easily - long chains do have lots of play on bumpy
surfaces.

> Is there a company that could supply an idler with sealed bearings?


Terracycle (http://www.terracycle.com/parts.htm) sells idler kits, single and
double for power side, return side, and over/under.