Scooterotica

andychain wrote:Tightness is only an issue where there is no tensioner. So although correct the 2-3% rule is for motorcycles.

The one in the picture will work fine, in fact it is good. There is a catena effect on chain chain
and the standard Lambretta tensioners work against it, the one shown works with it.

Andy

Thanks Andy

andychain wrote:Tightness is only an issue where there is no tensioner. So although correct the 2-3% rule is for motorcycles.

The one in the picture will work fine, in fact it is good. There is a catena effect on chain chain
and the standard Lambretta tensioners work against it, the one shown works with it.

Andy

Anyone use the Casa X4 pull down guide and thoughts on that...and any further explanantion on the 'Catena Effect' ..........are we saying the pull down method is more logical than the push up, just interested in how this all works from the physics side.....

The lower run is the "pull" side, the chain is under tension when you add power, and the top run becomes slack, or slacker.
The "pull down" top guides help stop this flapping about and allow a wider choice of chain - because you can adjust and control the otherwise thrashing chain. The lower run will pretty much take care of itself providing there is not too much slack.

A caternary curve happens when you fix a chain to two separated, fixed points. It is the natural curve which the cable\chain will adopt due to gravity.
See also suspension bridge. Brunel's bridge at Clifden, Bristol, uses plates configured like chain.
The word caternary drives from the latin for chain.

Hi Warts, is it advantageous to still include a lower guide ? I was thinking of the lower 'Green' slipper rather than the original innocenti one to potentially stop any slap against the base of the engine casing. One thing that strikes me is the X4 has an aluminium block into the case below where the chain runs on the pull down system and wondered if potentially under wear the chain could 'slap' or 'grate' on this metal block ......

The pull down style of chain tensioner\guide should be controlling the slack and therefore prevent the rubbing and banging.

I have heard it said that a lower guide as per the Lambretta ones can get snagged, but perhaps that is with a floppy chain.