Topic: Newbie's question about chains ...

[Punjanaman]

Hi Everbody,
 iam brand new to the forum and the C5 so forgive me if iam asking questions that have been asked 1000 times before or if i have put this question in the wrong section of the forum .
This is my first C5, i normally restore autocycles and unusual/rare scooters but wanted a change for something to do over the winter so i dragged "Clive" out of an old garage and plan to rejuvenate him over the next few months.
He appears to be complete if somewhat battered and abused with only a few minor parts missing or broken...I plan to ask LOTS of questions over the coming weeks but firstly...
The chain tensioner was hanging off Clive when i bought him and after cleaning/greasing the chain it became clear that the small "cup" that the tensioner arm pivots on is missing ...5 mins on youtube and i saw the piece that  was missing...and 5 mins in the garage with a piece of scrap polypropylene and a file has made a rough "cup".Problem is the tensioner works perfectly when pedalling normally but if i try to back pedal the tensioner locks -up.I should explain...i do not mean the jockey wheel jams, instead the backward motion of the chain pulls the tensioner upright(i.e. relieving the spring tension) until it flips backwards and de-rails the chain...Which got me to thinking ..is this a design problem????Can you back pedal a C5  ???do they all de-rail the chain if you back pedal???.My poly block "Cup" is as close to original as feasible and thought i would get some advice before re-building /designing the whole unit.

[Phoenix]

Hi my c5 can be back peddled with no problems, so you must have a problem somewhere, my chain tensioner is the original, but have a look on the chas section( goto home and scroll down) as he does sell modified ones that don't need the cup part, hopefully that will fix it, I'm sure others on the forum will be able to offer other ideas to fix it, good luck

[Punjanaman]

Experimented with a mark2 design yesterday...the "c" was made much deeper and is now a "U" section and the base of the U is now as close to the chassis as i dare.This design is much improved and allows the chain to back pedal without any problem ...However...Whilst the u shape prevents the tensioner arm from popping out and holds it in place much better  the " self lubricating " properties of the polypropylene are the designs worst enemy, it not only allows the arm to pivot smoothly it also allows it to slide up and out when you back pedal !!!
So i will build a final mark 3 version tonight( it only takes 5 mins to file and saw this plastic).This version will have thicker "U" walls but the base of the "U" will be wider to create a ball and socket effect...but i cant help thinking iam flogging a dead horse..I had read the previous thread about using a solid hinge to locate the arm and i get a feeling thats what will be happening at the weekend!

[KarlG]

Hi Punjanaman,

Chas also sells the 'small "cup"'.